should toss you up towards the Stars It 's true that by the other senses but yet assisted by Reason you may perceive the motion of the boat that is with the sight in that you see the trees and buildings placed on the shoar which being separated from the boat seem to move the contrary way But if you would by such an experiment receive intire satisfaction in this business of the Terrestrial motion look on the stars which upon this reason seem to move the contrary way As to the wondering that we should not feel such a principle supposing it to be internal is a less reasonable conceit for if we do not feel such a one that cometh to us from without and that frequently goeth away with what reason can we expect to feel it if it immutably and continually resides in us Now let us see what you have farther to allege on this argument SIMP Take this short exclamation Ex hac itaque opinione necesse est diffidere nostris sensibus ut penitùs fallacibus vel stupidis in sensilibus etiam conjunctissimis dijudicandis Quam ergò veritatem sperare possumus à facultate adeò fallaci ortum trahentem Which I render thus From this opinion likewise we must of necessity suspect our own senses as wholly fallible or stupid in judging of sensible things even very near at hand What truth therefore can we hope for to be derived from so deceiveable a faculty SALV But I desire not to deduce precepts more profitable or more certain learning to be more circumspect and less confident about that which at first blush is represented to us by the senses which may easily deceive us And I would not have this Author trouble himself in attempting to make us comprehend by sense that this motion of descending Graves is simply right and of no other kind nor let him exclaim that a thing so clear manifest and obvious should be brought in question for in so doing he maketh others believe that he thinketh those that deny that motion to be absolutely streight but rather circular the stone did sensibly see it to move in an arch seeing that he inviteth their senses more than their Reason to judg of that effect which is not true Simplicius for like as I that am indifferent in all these opinions and onely in the manner of a Comedian personate Copernicus in these our representations have never seen nor thought that I have seen that stone fall otherwise than perpendicularly so I believe that to the eyes of all others it seemed to do the same Better it is therefore that deposing that appearance in which all agree we make use of our Reason either to confirm the reality of that or to discover its fallacy SAGR. If I could any time meet with this Philosopher who yet me thinks is more sublime than the rest of the followers of the same doctrines I would in token of my affection put him in mind of an accident which he hath doubtless very often beheld from which with great conformity to that which we now discourse of it may be collected how easily one may be deceived by the bare appearance or if you will representation of the sense And the accident is the Moons seeming to follow those that walk the streets in the night with a pace equal to theirs whilst they see it go gliding along the Roofs of houses upon which it sheweth just like a cat that really running along the ridges of houses leaveth them behind An appearance that did not reason interpose would but too manifestly delude the sight SIMP Indeed there want not experiments that render us certain of the fallacy of the meer senses therefore suspending such sensations for the present let us hear the Arguments that follow which are taken as he saith ex rerum natura The first of which is that the Earth cannot of its own nature move with three motions very different or otherwise we must deny many manifest Axioms The first whereof is that Omnis effectus dependeat ab aliquâ causà i. e. that every effect dependeth on some cause The second that Nulla res seipsam producat i. e. that nothing produceth it self from whence it follows that it is not possible that the move and moved should be totally the same thing And this is manifest not onely in things that are moved by an extrinsick mover but it is gathered also from the principles propounded that the same holdeth true in the natural motion dependent on an intrinsick principle otherwise being that the mover as a mover is the cause and the thing moved as moved is the effect the same thing would totally be both the cause and effect Therefore a body doth not move its whole self that is so as that all moveth and all is moved but its necessary in the thing moved to distinguish in some manner the efficient principle of the motion and that which with that motion is moved The third Axiom is that in rebus quae sensui subjiciuntur unum quatenus unum unam solam rem producat i. e. That in things subject to the senses one as it is one produceth but onely one thing That is the soul in animals produceth its true divers operations as the sight the hearing the smell generation c. but all these with several instruments And in short in things sensible the diversity of operations is observed to derive it self from the diversity that is in the cause Now if we put all these Axioms together it will be a thing very manifest that one simple body as is the Earth cannot of its own nature move at the same time with three motions very divers For by the foregoing suppositions all moveth not its self all it is necessary therefore to distinguish in it three principles of its three motions otherwise one and the same principle would produce many motions but if it contein in it three principles of natural motions besides the part moved it shall not be a simple body but compounded of three principle movers and of the part moved If therefore the Earth be a simple body it shall not move with three motions nay more it will not move with any of those which Copernicus ascribeth to it it being to move but with one alone for that it is manifest by the reasons of Aristotle that it moveth to its centre as its parts do shew which descend at right angles to the Earths Spherical Surface SALV Many things might be said and considered touching the connection of this argument but in regard that we can resolve it in few words I will not at this time without need inlarge upon it and so much the rather because the same Author hath furnished me with an answer when he saith that from one sole prinple in animals there are produced divers operations so that for the present my answer shall be that in the same manner the Earth from one onely
so between them both compose this our Globe writeth that the seeing the small * particles of water shape themselves into rotundity as in the drops and in the dew daily apparent upon the leaves of several herbs is a strong argument and because according to the trite Axiome there is the same reason for the whole as for the parts the parts affecting that same figure it is necessary that the same is proper to the whole Element and truth is methinks it is a great oversight that these men should not perceive so apparent a vanity and consider that if their argument had run right it would have followed that not only the small drops but that any whatsoever greater quantity of water separated from the whole Element should be reduced into a Globe Which is not seen to happen though indeed the Senses may see and the Understanding perceive that the Element of Water loving to form it self into a Spherical Figure about the common centre of gravity to which all grave bodies tend that is the centre of the Terrestrial Globe it therein is followed by all its parts according to the Axiome so that all the surfaces of Seas Lakes Pools and in a word of all the parts of Waters conteined in vessels distend themselves into a Spherical Figure but that Figure is an arch of that Sphere that hath for its centre the centre of the Terrestrial Globe and do not make particular Spheres of themselves SALV The errour indeed is childish and if it had been onely the single mistake of Sacrobosco I would easily have allowed him in it but to pardon it also to his Commentators and to other famous men and even to Ptolomy himselfe this I cannot do without blushing for their reputation But it is high time to take leave it now being very late and we being to meet again to morrow at the usual hour to bring all the foregoing Discourses to a final conclusion Place this Plate at the end of the third Dialogue GALILAEUS Gailaeus Lyncaeus HIS SYSTEME OF THE WORLD The Fourth Dialogue INTERLOCVTORS SALVIATUS SAGREDUS SIMPLICIUS SAGR. I know not whether your return to our accustomed conferences hath really been later than usual or whether the desire of hearing the thoughts of Salviatus touching a matter so curious hath made me think it so But I have tarried a long hour at this window expecting every moment when the Gondola would appear that I sent to fetch you SALV I verily believe that your imagination more than our tarriance hath prolonged the time and to make no longer demurre it would be well if without interposing more words we came to the matter it self and did shew that nature hath permitted whether the business in rei veritate be so or else to play and sport with our Fancies hath I say hath permitted that the motions for every other respect except to resolve the ebbing and flowing of the Sea assigned long since to the earth should be found now at last to answer exactly to the cause thereof and as it were with mutual a emulation the said ebbing and flowing to appear in confirmation of the Terrestrial motion the judices whereof have hitherto been taken from the coelestial Phaenomena in regard that of those things that happen on Earth not any one was of force to prove one opinion more than another as we already have at large proved by shewing that all the terrene occurrences upon which the stability of the Earth and mobility of the Sun and Firmament is commonly inferred are to seem to us performed in the same manner though we supposed the mobility of the Earth and the immobility of them The Element of Water onely as being most vast and which is not annexed and concatenated to the Terrestrial Globe as all its other solid parts are yea rather which by reason of its fluidity remaineth apart sui juris and free is to be ranked amongst those sublunary things from which we may collect some hinte and intimation of what the Earth doth in relation to motion and rest After I had many and many a time examined with my self the effects and accidents partly seen and partly understood from others that are to be observed in the motions of waters and moreover read and heard the great vanities produced by many as the causes of those accidents I have been induced upon no slight reasons to omit these two conclusions having made withal the necessary presupposals that in case the terrestrial Globe be immoveable the flux and reflux of the Sea cannot be natural and that in case those motions be conferred upon the said Globe which have been long since assigned to it it is necessary that the Sea be subject to ebbing and flowing according to all that which we observe to happen in the same SAGR. The Proposition is very considerable as well for it self as for what followeth upon the same by way of consequence so that I shall the more intensly hearken to the explanation and confirmation of it SALV Because in natural questions of which number this which we have in hand is one the knowledge of the effects is a means to guide us to the investigation and discovery of the causes and without which we should walk in the dark nay with more uncertainty for that we know not whither we would go whereas the blind at least know where they desire to arrive therefore first of all it is necessary to know the effects whereof we enquire the causes of which effects you Sagredus ought more abundantly and more certainly to be informed than I am as one that besides your being born and having for a long time dwelt in Venice where the Tides are very notable for their greatnesse have also sailed into Syria and as an ingenuous and apprehensive wit must needs have made many Observations upon this subject whereas I that could onely for a time and that very short observe what happened in these extream parts of the Adriatick Gulph and in our Seas below about the Tyrrhene shores must needs take many things upon the relation of others who for the most part not very well agreeing and consequently being very uncertain contribute more of confusion than confirmation to our speculations Neverthelesse from those that we are sure of and which are the principal I think I am able to attain to the true and primary causes not that I pretend to be able to produce all the proper and adequate reasons of those effects that are new unto me and which consequently I could never have thought upon And that which I have to say I propose only as a key that openeth the door to a path never yet trodden by any in certain hope that some wits more speculative than mine will make a further progresse herin and penetrate much farther than I shall have done in this my first Discovery And although that in other Seas remote from us there may â—appen several accidents which
of the ebbing and flowing you must finde and give us some reason why it doth in the self same place run one while one way and another while another Effects that being contrary irregular can never be deduced from any uniform and constant Cause And this Argument that overthrows the Hypothesis of the motion contributed to the Sea from the Heavens diurnal motion doth also confute that Position of those who would admit the sole diurnal motion of the Earth and believe that they are able with that alone to give a reason of the Flux and Reflux Of which effect since it is irregular the cause must of necessity be irregular and alterable SIMP I have nothing to reply neither of my own by reason of the weakness of my understanding nor of that of others for that the Opinion is so new But I could believe that if it were spread amongst the Schools there would not want Phylosophers able to oppose it SAGR. Expect such an occasion and we in the mean time if it seem good to Salviatus will proceed forward SALV All that which hath been said hitherto pertaineth to the diurnal period of the ebbing and flowing of which we have in the first place demonstrated in general the primary and universal Cause without which no such effect would follow Afterwâ—â—ds passing to the particular Accidents various and in a certain sort irregular that are observed therein We have handled the secondary and concommitant Causes upon which they depend Now follow the two other Periods Monethly and Annual which do not bring with them new and different Accidents other than those already considered in the diurnal Period but they operate on the same Accidents by rendring them greater and lesser in several parts of the Lunar Moneth and in several times of the Solar Year as if that the Moon and Sun did each conceive it self apart in operating and producing of those Effects a thing that totally clasheth with my understanding which seeing how that this of Seas is a local and sensible motion made in an immense mass of Water it cannot be brought to subscribe to Lights to temperate Heats to predominacies by occult Qualities and to such like vain Imaginations that are so far from being or being possible to be Causes of the Tide that on the contrary the Tide is the cause of them that is of bringing them into the brains more apt for loquacity and ostentation than for the speculation and discovering of the more abstruse secrets of Nature which kind of people before they can be brought to pronounce that wise ingenious and modest sentence I know it not suffer to escape from their mouths and pens all manner of extravagancies And the onely observing that the same Moon and the same Sun operate not with their light with their motion with great heat or with temperate on the lesser reeeptaclâ—s of Water but that to effect their flowing by heat they must be reduced to little lesse than boiling and in short we not being able artificially to imitate any way the motions of the Tide save only by the motion of the Vessel ought it not to satisfie every one that all the other things alledged as causes of those effects are vaine fancies and altogether estranged from the Truth I say therefore that if it be true that of one effect there is but one sole primary cause and that between the cause and effect there is a firm and constant connection it is necessary that whensoever there is seen a firm and constant alteration in the effect there be a firm and constant alteration in the cause And because the alterations that happen in the ebbing and flowing in several parts of the Year and Moneths have their periods firm and constant it is necessary to say that a regular alteration in those same times happeneth in the primary cause of the ebbings and flowings And as for the alteration that in those times happens in the ebbings and flowings consisteth onely in their greatness that is in the Waters rising and falling more or lesse and in running with greater or lesse impetus therefore it is necessary that that which is the primary cause of the ebbing and flowing doth in those same determinate times increase and diminish its force But we have already concluded upon the inequality and irregularity of the motion of the Vessels containing the Water to be the primary cause of the ebbings and flowings Therefore it is necessary that that irregularity from time to time correspondently grow more irregular that is grow greater and lesser Now it is requisite that we call to minde that the irregularity that is the different velocity of the motions of the Vessels to wit of the parts of the Terrestrial Superficies dependeth on their moving with a compound motion resulting from the commixtion of the two motions Annual and Diurnal proper to the whole Terrestrial Globe of which the Diurnal conversion by one while adding to and another while substracting from the Annual motion is that which produceth the irregularity in the compound motion so that in the additions and substractions that the Diurnal revolution maketh from the Annual motion consisteth the original cause of the irregular motion of the Vessels and consequently of the Ebbing and Flowing insomuch that if these additions and substractions should alwayes proceed in the same proportion in respect of the Annual motion the cause of the Ebbing and Flowing would indeed continue but yet so as that they would perpetually return in the self same manner But we are to finde out the cause of making the same Ebbings and Flowings in divers times greater and lesser Therefore we must if we will retain the identity of the cause find the alteration in these additions and substractions that make them more less potent in producing those effects which depend thereupon But I see not how that potency and impotence can be introduced unlesse by making the same additions and substractions one while greater and another while lesser so that the acceleration and the retardment of the compound motion may be made sometimes in greater and sometimes in lesser proportion SAGR. I feel my self very gently led as it were by the hand and though I finde no rubs in the way yet neverthelesse like a blind man I see not whether your Clue leadeth me nor can I imagine where such a Journey will end SALV Though there be a great difference between my slow pac't Philosophy and your more nimble Reason yet neverthelesse in this particular which we are now upon I do not much wonder if the apprehensivenesse of your wit be a little obscured by the dark and thick mist that hides the mark at which we aime and that which lesseneth my admiration is the remembrance of the many hours many dayes yea more many nights that I have consumed in this contemplation and of the many times that despairing to bring it to a period I have for an incouragement of my self
been a little greater Mathematician and particularly well grounded in Geometry the practice whereof would have rendered him less resolute in accepting those reasons for true Demonstrations which he produceth for true causes of the true conclusions observed by himself Which reasons freely speaking do not knit and bind so fast as those undoubtedly ought to do in that of natural necessary and lasting conclusions may be alledged And I doubt not but that in processe of time this new Science will be perfected with new observations and which is more with true and necessary Demonstrations Nor ought the glory of the first Inventor to be thereby diminished nor do I lesse esteem but rather more admire the Inventor of the Harp although it may be supposed that the Instrument at first was but rudely framed and more rudely fingered than an hundred other Artists that in the insuing Ages reduced that profession to great perfection And methinks that Antiquity had very good reason to enumerate the first Inventors of the Noble Arts amongst the Gods seeing that the common wits have so little curiosity and are so little regardful of rare and elegant things that though they see and hear them exercitated by the exquisite professors of them yet are they not thereby perswaded to a desire of learning them Now judge whether Capacities of this kind would ever have attempted to have found out the making of the Harp or the invention of Musick upon the hint of the whistling noise of the dry sinews of a Tortois or from the striking of four Hammers The application to great inventions moved by small hints and the thinking that under a primary and childish appearance admirable Arts may lie hid is not the part of a trivial but of a super-humane spirit Now answering to your demands I say that I also have long thought upon what might possibly be the cause of this so tenacious and potent union that we see to be made between the one Iron that armeth the Magnet and the other that conjoyns it self unto it And first we are certain that the vertue and strength of the stone doth not augment by being armed for it neither attracts at greater distance nor doth it hold an Iron the faster if between it and the arming or cap a very fine paper or a leaf of beaten gold be interposed nay with that interposition the naked stone takes up more Iron than the armed There is therefore no alteration in the vertue and yet there is an innovation in the effect And because its necessary that a new effect have a new cause if it be inquired what novelty is introduced in the act of taking up with the cap or arming there is no mutation to be discovered but in the different contact for whereas before Iron toucht Loadstone now Iron toucheth Iron Therefore it is necessary to conclude that the diversity of contacts is the cause of the diversity of effects And for the difference of contacts it cannot as I see be derived from any thing else save from that the substance of the Iron is of parts more subtil more pure and more compacted than those of the Magnet which are more grosse impure and rare From whence it followeth that the superficies of two Irons that are to touch by being exquisitely plained filed and burnished do so exactly conjoyn that all the infinite points of the one meet with the infinite points of the other so that the filaments if I may so say that collegate the two Irons are many more than those that collegate the Magnet to the Iron by reason that the substance of the Magnet is more porous and lesse compact which maketh that all the points and filaments of the Loadstone do not close with that which it unites unto In the next place that the substance of Iron especially the well refined as namely the purest steel is of parts much more dense subtil and pure than the matter of the Loadstone is seen in that one may bring its edge to an extraordinary sharpnesse such as is that of the Rasor which can never be in any great measure effected in a piece of Magnet Then as for the impurity of the Magnet and its being mixed with other qualities of stone it is first sensibly discovered by the colour of some little spots for the most part white and next by presenting a needle to it hanging in a thread which upon those stonynesses cannot find repose but being attracted by the parts circumfused seemeth to fly from those and to leap upon the Magnet contiguous to them and as some of those Heterogeneal parts are for their magnitude very visible so we may believe that there are others in great abundance which for their smallnesse are imperceptible that are disseminated throughout the whole masse That which I say namely that the multitude of contacts that are made between Iron and Iron is the cause of the so solid conjunction is confirmed by an experiment which is this that if we present the sharpned point of a needle to the cap of a Magnet it will stick no faster to it than to the same stone unarmed which can proceed from no other cause than from the equality of the contacts that are both of one sole point But what then Let a Needle be taken and placed upon a Magnet so that one of its extremities hang somewhat over and to that present a Nail to which the Needle will instantly cleave insomuch that withdrawing the Nail the Needle will stand in suspense and with its two ends touching the Magnet and the Iron and withdrawing the Nail yet a little further the Needle will forsake the Magnet provided that the eye of the Needle be towards the Nail and the point towards the Magnet but if the eye be towards the Loadstone in withdrawing the Nail the Needle will cleave to the Magnet and this in my judgment for no other reason save onely that the Needle by reason it is bigger towards the eye toucheth in much more points than its sharp point doth SAGR. Your whole discourse hath been in my judgment very concluding and this experiment of the Needle hath made me think it little inferiour to a Mathematical Demonstration and I ingenuously confesse that in all the Magnetick Philosophy I never heard or read any thing that with such strong reasons gave account of its so many admirable accidents of which if the causes were with the same perspicuity laid open I know not what sweeter food our Intellects could desire SALV In seeking the reasons of conclusions unknown unto us it is requisite to have the good fortune to direct the discourse from the very beginning towards the way of truth in which if any one walk it will easily happen that one shall meet with several other Propositions known to be true either by disputes or experiments from the certainty of which the truth of ours acquireth strength and evidence as it did in every respect
do not happen in our Mediterranean Sea yet doth not this invalidate the reason and cause that I shall produce if so be that it verifie and fully resolve the accidents which evene in our Sea for that in conclusion there can be but one true and primary cause of the effects that are of the same kind I will relate unto you therefore the effects that I know to be true and assigne the causes thereof that I think to be true and you also Gentlemen shall produce such others as are known to you besides mine and then we will try whether the cause by me alledged may satisfie them also I therefore affirm the periods that are observed in the fluxes and refluxes of the Sea-waters to be three the first and principal is this great and most obvious one namely the diurnal according to which the intervals of some hours with the waters flow and ebbe and these intervals are for the most part in the Mediterrane from six hours to six hours or thereabouts that is they for six hours flow and for six hours ebbe The second period is monethly and it seemes to take its origen from the motion of the Moon not that it introduceth other motions but only altereth the greatnesse of those before mentioned with a notable difference according as it shall wax or wane or come to the Quadrature with the Sun The third Period is annual and is seen to depend on the Sunne and onely altereth the diurnal motions by making them different in the times of the Solstices as to greatnesse from what they are in the Equinoxes We will speak in the first place of the diurnal motion as being the principal and upon which the Moon and Sun seem to exercise their power secondarily in their monethly and annual alterations Three differences are observable in these horary mutations for in some places the waters rise and fall without making any progressive motion in others without rising or falling they run one while towards the East and recur another while towards the West and in others they vary the heights and course also as happeneth here in Venice where the Tides in coming in rise and in going out fall and this they do in the extermities of the lengths of Gulphs that distend from West to East and terminate in open shores up along which shores the Tide at time of flood hath room to extend it self but if the course of the Tide were intercepted by Cliffes and Banks of great height and steepnesse there it will flow and ebbe without any progressive motion Again it runs to and again without changing height in the middle parts of the Mediterrane as notably happeneth in the Faro de Messina between Scylla and Carybdis where the Currents by reason of the narrownesse of the Channel are very swift but in the more open Seas and about the Isles that stand farther into the Mediterranean Sea as the Baleares Corsica Sardignia Elba Sicily towards the Affrican Coasts Malta Candia c. the changes of watermark are very small but the currents indeed are very notable and especially when the Sea is pent between Islands or between them and the Continent Now these onely true and certain effects were there no more to be observed do in my judgment very probably perswade any man that will contain himself within the bounds of natural causes to grant the mobility of the Earth for to make the vessel as it may be called of the Mediterrane stand still and to make the water contained therein to do as it doth exceeds my imagination and perhaps every mans else who will but pierce beyond the rinde in these kind of inquiries SIMP These accidents Salviatus begin not now they are most ancient and have been observed by very many and several have attempted to assigne some one some another cause for the same and there dwelleth not many miles from hence a famous Peripatetick that alledgeth a cause for the same newly fished out of a certain Text of Aristotle not well understood by his Expositors from which Text he collecteth that the true cause of these motions doth only proceed from the different profundities of Seas 〈…〉 waters of greatest depth being greater in abundance and therefore more grave drive back the Waters of lesse depth which being afterwards raised desire to descend and from this continual colluctation or contest proceeds the ebbing and flowing Again those that referre the same to the Moon are many saying that she hath particular Domination over the Water and at last a certain Prelate hath published a little Treatise wherâ—in he saith that the Moon wandering too and fro in the Heavens attracteth and draweth towards it a Masse of Water which goeth continually following it so that it is full Sea alwayes in that part which lyeth under the Moon and because that though she be under the Horizon yet neverthelesse the Tide returneth he saith that no more can be said for the salving of that particular save onely that the Moon doth not onely naturally retain this faculty in her self but in this case hath power to confer it upon that degree of the Zodiack that is opposite unto it Others as I believe you know do say that the Moon is able with her temperate heat to rarefie the Water which being rarefied doth thereupon flow Nor hath there been wanting some that SAGR. I pray you Simplicius let us hear no more of them for I do not think it is worth the while to wast time in relating them or to spend our breath in confuting them and for your part if you gave your assent to any of these or the like fooleâ—ies you did a great injury to your judgment which neverthelesse I acknowledg to be very piercing SALV But I that am a little more flegmatick than you Sagredus will spend a few words in favour of Simplicius if haply he thinks that any probability is to be found in those things that he hath related I say therefore The Waters Simplicius that have their exteriour superficies higher repel those that are inferiour to them and lower but so do not those Waters that are of greatest profundity and the higher having once driven back the lower they in a short time grow quiet and level This your Peripatetick must needs be of an opinion that all the Lakes in the World that are in a calme and that all the Seas where the ebbing and flowing is insensible are level in their bottoms but I was so simple that I perswaded my self that had we no other plummet to sound with the Isles that advance so high above Water had been a sufficient evidence of the unevennesse of their bottomes To that Prelate I could say that the Moon runneth every day along the whole Mediterrane and yet its Waters do not rise thereupon save onely in the very extream bounds of it Eastward and here to us at Venice And for those that make the Moons
temperate heat able to make the Water swell bid them put fire under a Kettle full of Water and hold their right hand therein till that the Water by reason of the heat do rise but one sole inch and then let them take it out and write off the tumefaction of the Sea Or at least desire them to shew you how the Moon doth to rarefie a certain part of the Waters and not the remainder as for instance these here of Venice and not those of Ancona Naples Genova the truth is Poetick Wits are of two kinds some are ready and apt to invent Fables and others disposed and inclined to believe them SIMP I believe that no man believeth Fables so long as he knows them to be so and of the opinions concerning the causes of ebbing and flowing which are many because I know that of one single effect there is but one single cause that is true and primary I understand very well and am certain that but one alone at the most can be true and for all the rest I am sure that they are fabulous and false and its possible that the true one may not be among those that have been hitherto produced nay I verily believe that it is not for it would be very strange that the truth should have so little light as that it should not be visible amongst the umbrages of so many falshoods But this I shall say with the liberty that is permitted amongst us that the introduction of the Earths motion and the making it the cause of the ebbing and flowing of Tides seemeth to me as yet a conjecture no lesse fabulous than the rest of those that I have heard and if there should not be proposed to me reasons more conformable to natural matters I would without any more ado proceed to believe this to be a supernatural effect and therefore miraculous and unsearchable to the understandings of men as infinite others there are that immediately depend on the Omnipotent hand of God SAGR. You argue very prudently and according to the Doctrine of Aristotle who you know in the beginning of his mechanical questions referreth those things to a Miracle the causes whereof are occult But that the cause of the ebbing and flowing is one of those that are not to be found out I believe you have no greater proof than onely that you see that amongst all those that have hitherto been produced for true causes thereof there is not one wherewith working by what artifice you will we are able to represent such an effect in regard that neither with the light of the Moon nor of the Sun nor with temperate heats nor with different profundities shall one ever artificially make the Water conteined in an immoveable Vessel to run one way or another and to ebbe and flow in one place and not in another But if without any other artifice but with the onely moving of the Vessel I am able punctually to represent all those mutations that are observed in the Sea Water why will you refuse this reason and run to a Miracle SIMP I will run to a Miracle still if you do not with some other natural causes besides that of the motion of the Vessels of the Sea-water disswade me from it for I know that those Vessels move not in regard that all the entire Terrestrial Globe is naturally immoveable SALV But do not you think that the Terrestrial Globe might supernaturally that is by the absolute power of God be made moveable SIMP Who doubts it SALV Then Simplicius seeing that to make the flux and reflux of the Sea it is necessary to introduce a Miracle let us suppose the Earth to move miraculously upon the motion of which the Sea moveth naturally and this effect shall be also the more simple and I may say natural amongst the miraculous operations in that the making a Globe to move round of which kind we see many others to move is lesse difficult than to make an immense masse of water go forwards and backwards in one place more swiftly and in another lesse and to rise and fall in some places more in some lesse and in some not at all and to work all these different effects in one and the same Vessel that containeth it besides that these are several Miracles and that is but one onely And here it may be added that the Miracle of making the water to move is accompanied with another namely the holding of the Earth stedfast against impetuosities of the water able to make it swage sometimes one way and sometimes another if it were not miraculously kept to rights SAGR. God Simplicius let us for the present suspend our judgement about sentencing the new opinion to be vain that Salviatus is about to explicate unto us nor let us so hastily flye out into passion like the scolding overgrown Haggs and as for the Miracle we may as well recurre to it when we have done hearing the Discourses contained within the bounds of natural causes though to speak freely all the Works of nature or rather of God are in my judgement miraculous SALV And I am of the same opinion nor doth my saying that the motion of the Earth is the Natural cause of the ebbing and flowing hinder but that the said motion of the Earth may be miraculous Now reassuming our Argument I apply and once again affirm that it hath been hitherto unknown how it might be that the Waters contained in our Mediterranean Straights should make those motions as we see it doth if so be the said Straight or containing Vessel were immoveable And that which makes the difficulty and rendreth this matter inextricable are the things which I am about to speak of and which are daily observed Therefore lend me your attention We are here in Venice where at this time the Waters are low the Sea calm the Air tranquil suppose it to be young flood and that in the term of five or six hours the water do rise ten hand breadths and more that rise is not made by the first water which was said to be rarefied but it is done by the accession of new Water Water of the same sort with the former of the same brackishness of the same density of the same weight Ships Simplicius float therein as in the former without drawing an hairs breadth more water a Barrel of this second doth not weigh one single grain more or less than such another quantity of the other and retaineth the same coldness without the least alteration And it is in a word Water newly and visibly entred by the Channels and Mouth of the Lio. Consider now how and from whence it came thither Are there happly hereabouts any Gulphs or Whirle-pools in the bottom of the Sea by which the Earth drinketh in and spueth out the Water breathing as it were a great and monstruous Whale But if this be so how comes it that the Water doth not flow in
Earth answered by Examples of the like Motions in other Celestial Bodies 236 A fourth Argument of Claramontius against the Copernican Hypothesis of the Earths Mobility 239 From the Earths obscurity and the splendor of the fixed Stars it is argued that it is moveable and they immoveable 239 A fifth Argument of Claramontius against the Copernican Hypothesis of the Earths Mobility 240 Another difference between the Earth and Celestial Bodies taken from Purity and impurity 240 It seems a Solecisme to affirme that the Earth is not in Heaven 241 Granting to the Earth the Annual it must of necessity also have the Diurnal Motion assigned to it 300 Discourses more than childish that serve to keep Fools in the Opinion of the Earths Stability 301 The Difficulties removed that arise from the Earths moving about the Sun not solitarily but in consort with the Moon 307 The Axis of the Earth continueth alwayes parallel to it self and describeth a Cylindraical Superficies inclining to the Orb. 344 The Orb of the Earth never inclineth but is immutably the same 345 The Earth approacheth or recedeth from the fixed Stars of the Ecliptick the quantity of the Grand Orb. 349 If in the fixed Stars one should discover any Mutation the Motion of the Earth would be undeniable 351 Necessary Propositions for the better conceiving of the Consequences of the Earths Motion 354 An admirable Accident depending on the not-inclining of the Earths Axis 358 Four several Motions assigned to the Earth 362 The third Motion ascribed to the Earth is rather a resting immoveable 363 An admirable interne vertue or faculty of the Earths Globe to behold alwayes the same part of Heaven 363 Nature as iâ— sport maketh the Ebbing and Flowing of the Sea to prove the Earths Mobility 379 All Terrene Effects indifferently confirm the Motion or Rest of the Earth except the Ebbing and Flowing of the Sea 380 The Cavities of the Earth cannot approach or recede from the Centre of the same 387 The Hypothesis of the Earths Mobility taken in favour of the Ebbing and Flowing opposed 399 The Answers to those Objections made against the Earths Motion 399 The Revolution of the Earth confirmed by a new Argument taken from the Aire 400 The vaporous parts of the Earth partake of its Motions 400 Another observation taken from the Ayr in confirmation of the motion of the Earth 402 A Reason of the continual Motion of the Air and Water may be given by making the Earth moveable rather then by making it immoveable 405 The Earths Mobility held by sundry great Philosophers amongst the Antients 437 468 The Fathers agree not in expounding the Texts of Scripture that are alledged against the Earths Mobility 450 The Earth Mobility defended by many amongst the Modern Writers 478 The Earth shall stand still after the Day of Judgement 480 The Earth is another Moon or Star 486 The Earths several Motions according to Copernicus 491 The Earth secundum totum is Immutable though not Immoveable 491 The Earths Natural Place 492 The Earths Centre keepeth her in her Natural Place 493 The Earth in what Sense it may absolutely be said to be in the lowest part of the World 496 EBBING and Ebbings The first general Conclusion of the impossibility of Ebbing and Flowing the Immobility of the Terrestrial Globe being granted 380 The Periods of Ebbings and Flowings Diurnal Monethly and Annual 381 Varieties that happen in the Diurnal Period of the Ebbings and Flowings 382 The Causes of Ebbings and Flowings alledged by a Modern Phylosopher 382 The Cause of the Ebbing and Flowing ascribed to the Moon by a certain Prelate 383 The Cause of the Ebbing c. referred by Hyeronimus Borrius and other Peripateticks to the temperate heat of the Moon 383 Answers to the Vanities alledged as Causes of the Ebbing and Flowing 383 It s proved impossible that there should naturally be any Ebbing and Flowing the Earth being immoveable 386 The most potent and primary Cause of the Ebbing and Flowing 390 Sundry accidents that happen in the Ebbings and Flowings 391 Reasons renewed of the particular Accidents observed in the Ebbings and Flowings 393 Second Causes why in several Seas and Lakes there are no Ebbings and Flowings 394 The Reason why the Ebbings and Flowings for the most part are every Six Hours 395 The Cause why some Seas though very long suffer no Ebbing and Flowing 395 Ebbings and Flowings why greatest in the Extremities of Gulphs and least in the middle parts 396 A Discussion of some more Abstruce Accidents observed in the Ebbing and Flowing 396 The Ebbing and Flowing may depend on the Diurnal Motion of Heaven 404 The Ebbing and Flowing cannot depend on the Motion of Heaven 405 The Causes of the Periods of the Ebbings and Flowings Monethly and Annual at large assigned 407 The Monethly and Annual alterations of the Ebbings and Flowings can depend on nothing save on the alteration of the Additions and Subtractions of the Diurnal Period from the Annual 408 Three wayes of altering the proportion of the Additions of the Diurnal Revolution to the Annual Motion of the Ebbing and Flowing 409 Ebbings and Flowings are petty things in comparison of the vastnesse of the Seas and the Velocity of the Motion of the Terrestrial Globe 417 EFFECT and Effects Of a new Effect its necessary that the Cause be likewise new 370 The Knowledge of the Effects contribute to the investigation of the Causes 380 True and Natural Effects follow without difficulty 387 Alterations in the Effects argue alteration in the Cause 407 ELEMENTS and their Motions Vide MOTION ENCYCLOPEDIA Subtilties sufficiently insipid ironically spoken and taken from a certain Encyclopedia 153 EXPERIMENTS Sensible Experiments are to be preferred before Humane Argumentations 21 33 42. It is good to be very cautious in admitting Experiments for true to those that never tryed them 162 Experiments and Arguments against the Earths Motion seem so far concluding as they lye under Equivokes 162 The Authority of Sensible Experiments and necessary Demonstrations in deciding of Physical Controversies 436 EYE The Circle of the Pupil of the Eye contracteth and enlargeth 329 How to finde the distance of the Rays Concourse from the Pupil of the Eye 329 F FAITH Faith more infallible than either Sense or Reason 475 FIRE Fire moveth directly upwards by Nature and round about by Participation according to Aristotle 122 It is improbable that the Element of Fire should be carried round by the Concave of the Moon 405 FIGURE and Figures Figure is not the Cause of Incorruptibility but of Longer Duration 66 The perfection of Figure appeareth in Corruptible Bodies but not in the Eternal 69 If the Spherical Figure conferred Eternity all things would be Eternal 69 It is more difficult to finde Figures that touch in a part of their Surface then in one sole point 185 The Circular Figure placed amongst the Postulata of Mathematicians 186 Irregular Figures and Formes difficult to be introduced 187 Superficial figures increase in proportion
of Tycho made with great expence What Instruments are apt for most exact observation * Italian braces An exquisite observation of the approach and departure of the Sun from the Summer Solstice A place accommodated for the observation of the fixed stars as to what concers the annual motion of the Earth The Copernican Systeme difficult to be understood but easie to be effected Necessary prepositions for the better conceiving of the consequences of the Earths motion A plain Scheme representing the Copernican Hypothesis and its consequences Axiomes commonly admitted by all Philosophers Aristotle taxeth Plato for being too studious of Geometry Peripatetick Philosophers condemn the Study of Geometry and why Four several motions assigned to the Earth The motion of descent belongs not to the terrestrial Globe but to its parts The annual and diurnal motion are compatible in the Earth Every pensil and librated body carryed round in the circumference of a circle acquireth of it self a motion in it self contrary to that An Experiment which sensibly shews that two contrary motions may naturally agree in the same moveable The third motion ascribed to the Earth is rather a resting immoveable An admirable intern vertue of the terrestrial Globe of alwayes beholding the same part of Heaven The terrestrial Globe made of Loade-stone * An eminent Doctor of Physick our Countreyman born at Colchester and famous for this his learned Treatise published about 60 years since at London The Magnetick Philosophy of William Gilbert The Pusillanimity of Popular Wits The Terrestrial Globe composed of sundry matters The interne parts of the terrestrial Globe must of necessity be solid * Or MOULD * Of which with the Latin translatour I must once more professe my self ignorant Our Globe would have been called stone in stead of Earth of that name had been giuen it in the beginning The method of Gilbert in his Philosophy Many properties in the Magnet 〈…〉 The Magnet armed takes up much more Iron than when armed * Or Closet of rarities The first observers and inventers of things ought to be admired The true cause of the multiplication of vertue in the Magnet by means of the arming Of a new effect its necessary that the cause be likewise new It is proved that Iron consists of parts more subtil pure and compact than the magnet A sensible proof of the impurity of the Magnet * The Author hereby meaneth that the stone doth not all consist of magnetick matter but that the whiter specks being weak those other parts of the Loadstone of a more dark constant colour contain all that vertue wherewith bodies are attracted * A common sewing needle Sympathy and Antipathy terms used by Philosophers to give a reason easily of many natural effests A pleasant example declaring the invalidity of some Phylosophical argumentations The several natural motions of the Magnet Aristole grants a compound motion to mixt bodies The motion of mixt bodies ought to be such as may result from the composition of the motions of the simple bodies compounding With two right motions one cannot compose circular motions Philosophers are forced to confesse that the Magnet is compounded of coelestial substances and of elementary The errour of those who call the Magnet a mixt body and the terrestrial Globe a simble body * Ogliopotrida a Spanish dish of many ingredients boild together The Discourses of Peripateticks full of errours and contradictions An improbable effect admired by Gilbertus in the Loadstone The vain argumentation of some to prove the Element of Water to be of a Spherical superficies Nature in sport maketh the ebbing and flowing of the Sea to approve the Earthâ— mobility The tide and mobility of the Earth mutually confirm each other All terrene effects indifferently confirm the motion or rest of the Earth except the ebbing and flowing of the Sea The first general conclusion of the impossibility of the ebbing and flowing the immobility of the terrestrial Globe being granted The knowledge of the effests contributes to the investigation of the causes Three Periods of ebbings and flowings diurnal monethly and annual Varieties that â—appen in the diurâ—â—â— period * A Strair so called * Or Ilva * Or Crets The cause of the ebbing and flowing alledged by a certain modern Philosopher The cause of the ebbing and flowing ascribed to the Moon by a certain Prelate Hieronymus Borrius and other Peripateticks refer it to the temperate heat of the Moon Answers to the vanities alledged as causes of the ebbing and flowing * Or rather smooth The Isles are tokens of the unevennesse of the bottomes of Seas Poetick wits of two kinds Truth hath not so little light as not to be discovered amidst the umbrages of falshoods Aristotle holdeth those effects to be miraculous of which the causes are unknown It is proved impossible that there should naturally be any ebbing and flowing the Earth being immoveable * Palms †Lio is a fair Port in the Venetian Gulph lying N. E. from the City True and natural effects follow without difficulty Two sorts of motions of the containing Vessel may make the contained water to rise and fall The Cavities of the Earth cannot approach or go farther from the centre of the same The progpessive and uneven motion may make the water contained in a Vessel to run to and fro * A Town lying S. E. of Venice The parts of the terrestrial Globe accelerate and regard in their motion Demonstrations how the parts of the terrestriall Globe accelerate and retard The parts of a Circle regularly moved about its own centre move in divers times with contrary motions The mixture of the two motions annnal and diurnal causeth the inequality in the motion of the parts of the terrestrial Globe The most potent and primary cause of the ebbing and flowing Sundry accidents that happen in the ebbings flowings The first accident The Water raised in one end of the Vessel returneth of its self to Aequilibrium In the shorter Vessels the undulations of waters are more frequent The greater profundity maketh the undulations of waters more frequent Water riseth falleth in the extream parts of the Vessel and runneth to and fro in the midst An accident of the Earths motions impossible to be reduced to practice by art Reasons renewed of the particnlar accidents observed in the ebbings and flowings Second causes why in small Seas and in Lakes there are no ebbings and flowings The reason given why the ebbings and flowings for the most part are every six hours The cause why some Seas though very long suffer no ebbing and flowing Ebbings and flowings why greatest in the extremities of Gulphs and least in the middle parts Why in narrow places the course of the waters is more swift than in larger A discussion of 〈…〉 â—abstruce 〈…〉 obseâ—ved 〈…〉 ebbing and â—â—â—wing The cause why in some narrow Channels we see the Sea-waters run alwayes one way * Or current The Hypothesis of the Earths mobility taken in favour of the
Tide opposed The answer to the objections made against the motion of the Terrestrial Globe * Corpulenta The Water more apt to conserve an impetus conceived then the Air. Light bodies easier to be moved than heavy but less apt to conserve the motion It s more rational that the Air be commoved by the rugged surface of the Earth than by the Celestial motion The revolution of the Earth confirmed by a new argument taken from the Air. The vaporous parts of the earth partake of its motions Constant gales within the Tropicks blow towards the VVest The course to the VVest India's easie the return difficult Winds from Land make rough the Seas Another observation taken from the Air in confirmation of the motion of the Earth * Which Wind with our English Mariners is called the Trade-wind The voiages in the Mediterrane from East to West are made in shorter times than from West to East It is demonstrated inverting the argument that the perpetual motion of the Air from East to West cometh from the motion of Heaven It is demonstrated inverting the argument that the perpetual motion of the Air from East to VVest cometh from the motion of Heaven The motion of the VVater dependeth on the motion of Heaven The flux and reflux may depend on the diurnal motion of Heaven A reason of the continual motion of the Air and VVater may be given making the Earth moveable then by making it immoveable It s improbable that the element of Fire should be carried round by the Concave of the Moon †A Treatise of our Author formerly cited The Ebbing and Flowing cannot depend on the motion of Heaven The alterations in the effects argue alteration in the cause The causes as large assigned of the Periods Monethly and Annual of the ebbings and flowings The monethly and annual alterations of the tide can depend upon nothing save on the alteration of the additions substractions of the diurnal period from the annual Three wayes of altering the proportion of the additions of the diurnal Revolution to the annual motion That which to us is hard to be understood is with Nature easie to be effected If the Diurnal motion should not alter the annual Period would cease The true Hypothesis may dispatch its revolutions in a shorter time in lesser circles than in greater the which is proved by two examples The first example The second example Two particular notable accidents in the penduli and their vibrations Admirable Problems of moveables descending by the Quadrant of a Circle and of those descending by all the cords of the whole Circle The Earths annual motion by the Ecliptick unequal by means of the Moons motion Many things may remain as yet unobserved in Astronomy Saturn for its slowness and Mercury for its rareness of appearing were amongst those that were last observed Particular structures of the Orbs of the Planets not yet well resolved The Sun passeth one half of the Zodiack nine days sooner than the other The Moons motion principally sought in the account of Eclipses Ebbings and flowings are petty things in comparison of the vastness of Seas and of the velocity of the motion of the Terrestrial Globe The causes of the inequality of the additions and substractions of the diurnal conversion from the annual motion One single motion of the terrestrial Globe sufficeth not to produce the Ebbing Flowing The opinion of Seleucus the Mathematician censured Kepler is with respect blamed Sig. Caesare Marsilius observeth the Meridian to be moveable a Nunc autem servatâ semper moderatione praegravitatis nihil credere de re observá temerè debemus 〈◊〉 forie quod postea veritas pâ—â—efecerit quamvis Libris Sanctis sive Testamenâ— Vetris sive Novi nullo modó esse possit adversum tamen propter amorem nostri erroris oderimus Lib. 2. Genesi ad Literam in fine c Si fortasscerunt Mataeologi qui cum omnum Mathematicum ignari sint tamen de â—is judicium assumunt propter aliquem locum Scripturae malè ad suum propositum detortum ausi fuerint hoc meum institutum repreâ—endere ac insectari illos nihil moror adeò ut etiam illorum judicium tanquam temerarium contemnam Non enim obscurum est Lactantium celelebrem alioqui Scriptorem sed Mathematicum parvum admodum pueriliter de forma Terrae loqui cùm deridet eos qui Terram Globâ— formam habere prodiderunt Itaque non debet mirum videri studiosis si qui tales nos etiam ridebunt Mathemata Mathematicis scribuntur quibus hi nostri labores si me non fallit opinio videbuntur etiam Reipublicae Ecclesiasticae conducere aliquid cujus Principatum Tua Sanctitas nunc tenâ—â— c Not definimus Deum primò Nâ—tura cognoscendum Deinde Doctrina recognescendum Natura ex operibus Doctrina ex pâ—aedicationibus Tertul. adver Marcion lib. 1. cap. 18. c Quaeri etiam solet quae forma figura Caeli credenda sit secundum Scripturas nostras Multi enim multum disputant de iis ribus quas majori prudentia nostri Autores omiserunt ad beatam vitam non profuturas discentibus occupaentes quod prius est multum prolixaâ— rebus salubribus impendenda temporum spatiae Quid enim ad â—e pertinet utrum Caelum sicut Sphaera undique concludat Terram in media Mundi â—ole libratam an eam ex una parte desuper velut discus operiat Sed quiaâ— de Fide agitur Scripturarum propter illam causam quam non semel commemoravimus Ne scilicet quisquam eloquia divina non intelligens cum de his rebus tale aliquid vel invenerit in Libris Nostris vel ex illis audiverit quod perceptis assertionibus adversari videatur nullo modo eis cetera utilia monentibus vel narrantibus vel praeâ—â—â—ntiantibus credat Breviter discendum est de figura Caeli hoc scisse Autores nostros quod veritas habet Sed Spiritum Dei qui per ipsos loquebatur noluisse ista docere homines nulli ad salutem profutura D. August Lib. 2. De Gen. ad literam Cap. 9. Idem etiam legitur apud Petrum Lombardum Magistrum Sententiarum d De Moitâ— etiam Caeli nonnulli fraâ—tres quaestionem movent utrum stet an moveatur quiaâ— si â—â—â—vetur inquiunt quomodo Firmamentum est Si autem stat quomodo Sydera quae in ipso fixa creduntur ab Oriente in Occidentem circuÌ„eunt Septentrionalibus breviores gyros juxta cardinem peragentibus ut Caelum si est alius nobis occulius cardo ex alio vertice sicut Sphaera si autem nullus alius cardo est vel uti discus rotari videatur Quibus respondeo Multum subtilibus laboriosis rationibus ista perquiri ut vere percipiaetur utrum ita an non ita sit quibus ineundis atque tractandis nec mihi jam tempus est nec illis esse debet quos ad salutem suam è Sanctae
would acquiese in granting that the Moon Venus and the other Planets were not of so bright and smooth a surface as a Looking-glass but wanted some small matter of it namely were as a silver plate onely boyled white but not burnished would this yet suffice to the making of it visible and apt for darting forth the light of the Sun SALV It would suffice in part but would not give a light so strong as it doth being mountainous and in sum full of eminencies and great cavities But these Philosophers will never yield it to be lesse polite than a glasse but far more if more it can be imagined for they esteeming that to perfect bodies perfect figures are most sutable it is necessary that the sphericity of those Coelestial Globes be most exact besides that if they should grant me some inequality though never so small I would not scruple to take any other greater for that such perfection consisting in indivisibles an hair doth as much detract from its perfection as a mountain SAGR. Here I meet with two difficulties one is to know the reason why the greater inequality of superficies maketh the stronger reflection of light the other is why these Peripatetick Gentlemen are for this exact figure SALV I will answer to the first and leave to Simplicius the care of making reply to the second You must know therefore that the same superficies happen to be by the same light more or less illuminated according as the rayes of illumination fall upon them more or lesse obliquely so that the greatest illumination is where the rayes are perpendicular And see how I will prove it to your sense I bend this paper so that one part of it makes an angle upon the other and exposing both these parts to the reflection of the light of that opposite Wall you see how this side which receiveth the rayes obliquely is lesse shining than this other where the reflection fals at right angles and observe that as I by degrees receive the illumination more obliquely it groweth weaker SAGR. I see the effect but comprehend not the cause SALV If you thought upon it but a minute of an hour you would find it but that I may not waste the time see a kind of demonstration thereof in Fig. 7. SAGR. The bare sight of this Figure hath fully satisfied me therefore proceed SIMPL. Pray you let me hear you out for I am not of so quick an apprehension SALV Fancie to your self that all the paralel lines which you see to depart from the terms A. B. are the rays which fall upon the line C. D. at right angles then incline the said C. D. till it hang as D. O. now do not you see that a great part of those rays which peirce C. D. pass by without touching D. O? If therefore D. O. be illuminated by fewer rays it is very reasonable that the light received by it be more weak Let us return now to the Moon which being of a spherical figure if its superficies were smooth as this paper the parts of its hemisphere illuminated by the Sun which are towards its extremity would receive much less light than the middle parts the rays falling upon them most obliquely and upon these at right angles whereupon at the time of full Moon when we see almost its whole Hemisphere illuminated the parts towards the midst would shew themselves to us with more splendor than those others towards the circumference which is not so in effect Now the face of the Moon being represented to me full of indifferent high mountains do not you see how their tops and continuate ridges being elevated above the convexity of the perfect spherical superficies come to be exposed to the view of the Sun and accommodated to receive its rays much less obliquely and consequently to appear as luminous as the rest SAGR. All this I well perceive and if there are such mountains its true the Sun will dart upon them much more directly than it would do upon the inclination of a polite superficies but it is also true that betwixt those mountains all the valleys would become obscure by reason of the vast shadows which in that time would be cast from the mountains whereas the parts towards the middle though full of valleys and hills by reason they have the Sun elevated would appear without shadow and therefore more lucid by far than the extreme parts which are no less diffused with shadow than light and yet we can perceive no such difference SIMPL. I was ruminating upon the like difficulty SALV How much readier is Simplicius to apprehend the objections which favour the opinions of Aristotle than their solutions I have a kind of suspition that he strives also sometimes to dissemble them and in the present case he being of himself able to hit upon the doubt which yet is very ingenious I cannot believe but that he also was advis'd of the answer wherefore I will attempt to wrest the same as they say out of his mouth Therefore tell me Simplicius do you think there can be any shadow where the rays of the Sun do shine SIMPL. I believe nay I am certain that there cannot for that it being the grand luminary which with its rays driveth away darkness it is impossible any tenebrosity should remain where it cometh moreover we have the definition that Tenebrae sunt privatio luminis SALV Therefore the Sun beholding the Earth Moon or other opacous body never seeth any of its shady parts it not having any other eyes to see with save its rays the conveyers of light and consequently one standing in the Sun would never see any thing of umbrage forasmuch as his visive rays would ever go accompanied with those illuminating beams of the Sun SIMPL. This is true without any contradiction SALV But when the Moon is opposite to the Sun what difference is there between the tract of the rayes of your sight and that motion which the Suns rayes make SIMPL. Now I understand you for you would say that the rayes of the sight and those of the Sun moving by the same lines we cannot perceive any of the obscure valleys of the Moon Be pleased to change this your opinion that I have either simulation or dissimulation in me for I protest unto you as I am a Gentleman that I did not guesse at this solution nor should I have thought upon it without your help or without long study SAGR. The resolutions which between you two have been alledged touching this last doubt hath to speak the truth satisfied me also But at the same time this consideration of the visible rayes accompanying the rayes of the Sun hath begotten in me another scruple about the other part but I know not whether I can expresse it right or no for it but just now comming into my mind I have not yet methodized it to my mind but let us see if we can all together make it
angles and to so speak excrescencies would corrupt But if we proceed to a more inward consideration that in those parts also towards the angles there are comprised other lesser bals of the same matter and therefore they also as being round must be also incorruptible and likewise in the remainders which environ these eight lesser Spheres a man may understand that there are others so that in the end resolving the whole Die into innumerable balls it must necessarily be granted incorruptible And the same discourse and resolution may be made in all other figures SALV Your method in making the conclusion for if v. g. a round Chrystal were by reason of its figure incorruptible namely received from thence a faculy of resisting all internal and external alterations we should not find that the joyning to it other Chrystal and reducing it v. g. into a Cube would any whit alter it within or without so as that it would thereupon become lesse apt to resist the new ambient made of the same matter than it was to resist the other of a matter different and especially if it be true that corruption is generated by contraries as Aristotle saith and with what can you enclose that ball of Crystal that is lesse contrary to it than Crystal it self But we are not aware how time flies away and it will be too late before we come to an end of our dispute if we should make so long discourses upon every particular besides our memories are so confounded in the multiplicity of notions that I can very hardly recal to mind the Propotsiions which I proposed in order to Simplicius for our consideration SIMPL. I very well remember them And as to this particular question of the montuosity of the Moon there yet remains unanswered that which I have alledged as the cause and which may very well serve for a solution of that Phaenomenon saying that it is an illusion proceeding from the parts of the Moon being unequally opacous and perspicuous SAGR. Even now when Simplicius ascribed the apparent Protnberancies or unevennesses of the Moon according to the opinion of a certain Peripatetick his friend to the diversly opacous and perspicuous parts of the said Moon conformable to which the like illusions are seen in Crystal and Jems of divers kinds I bethought my self of a matter much more commodious for the representing such effects which is such that I verily believe that that Philosopher would give any price for it and it is the mother of Pearl which is wrought into divers figures and though it be brought to an extreme evennesse yet it seemeth to the eye in several parts so variously hollow and knotty that we can scarce credit our feeling of their evennesse SALV This invention is truly ingenious and that which hath not been done already may be done in time to come and if there have been produced other Jems and Crystals which have nothing to do with the illusions of the mother of Pearl these may be produced also in the mean time that I may not prevent any one I will suppresse the answer which might be given and onely for this time betake my self to satisfie the objections brought by Simplicius I say therefore that this reason of yours is too general and as you apply it not to all the appearances one by one which are seen in the Moon and for which my self and others are induced to hold it mountainous I believe you will not find any one that will be satisfied with such a doctrine nor can I think that either you or the Author himself find in it any greater quietude than in any other thing wide from the purpose Of the very many several appearances which are seen night by night in the course of Moon you cannot imitate so much as one by making a Ball at your choice more or less opacous and perspicuous and that is of a polite superficies whereas on the contrary one may make Balls of any solid matter whatsoever that is not transparent which onely with eminencies and cavities and by receiving the illumination several ways shall represent the same appearances and mutations to an hair which from hour to hour are discovered in the Moon In them you shall see the ledges of Hills exposed to the Suns light to be very shining and after them the projections of their shadows very obscure you shall see them greater and less according as the said eminencies shall be more or less distant from the confines which distinguish the parts of the Moon illuminated from the obscure you shall see the same term and confine not equally distended as it would be if the Ball were polish'd but craggie and rugged You shall see beyond the same term in the dark parts of the Moon many bright prominencies and distinct from the rest of the illuminations you shall see the shadows aforesaid according as the illumination gradually riseth to deminish by degrees till they wholly disappear nor are there any of them to be seen when the whole Hemisphere is enlightned Again on the contrary in the lights passage towards the other Hemisphere of the Moon you shall again observe the same eminencies that were marked and you shall see the projections of their shadows to be made a contrary way and to decrease by degrees of which things once more I say you cannot shew me so much as one in yours that are opacous and perspicuous SAGR. One of them certainly he may imitate namely that of the Full-Moon when by reason of its being all illuminated there is not to be seen either shadow or other thing which receiveth any alteration from its eminencies and cavities But I beseech you Salviatus let us spend no more time on this Argument for a person that hath had but the patience to make observation of but one or two Lunations and is not satisfied with this most sensible truth may well be adjudged void of all judgment and upon such why should we throw away our time and breath in vain SIMPL. I must confess I have not made the observations for that I never had so much curiosity or the Instruments proper for the business but I will not fail to do it In the mean time we may leave this question in suspense and pass to that point which follows producing the motives inducing you to think that the Earth may reflect the light of the Sun no less forceably than the Moon for it seems to me so obscure and opacous that I judg such an effect altogether impossible SALV The cause for which you repute the Earth unapt for illumination may rather evince the contrary And would it not be strange Simplicius if I should apprehend your discourses better than you your self SIMPL. Whether I argue well or ill it may be that you may better understand the same than I but be it ill or well that I discourse I shall never believe that you can penetrate what I mean better than I
And because in the last place the bird swending its flight towards the West was no other than a withdrawing from the diurnal motion which hath suppose ten degrees of velocity one degree onely there did thereupon remain to the bird whil'st it was in its flight nine degrees of velocity and so soon as it did alight upon the the Earth the ten common degrees returned to it to which by flying towards the East it might adde one and with those eleven overtake the Tower And in short if we well consider and more narrowly examine the effects of the flight of birds they differ from the projects shot or thrown to any part of the World in nothing save onely that the projects are moved by an external projicient and the birds by an internal principle And here for a final proof of the nullity of all the experiments before illedged I conceive it now a time and place convenient to demonstrate a way how to make an exact trial of them all Shut your self up with some friend in the grand Cabbin between the decks of some large Ship and there procure gnats flies and such other small winged creatures get also a great tub or other vessel full of water and within it put certain fishes let also a certain bottle be hung up which drop by drop letteth forth its water into another bottle placed underneath having a narrow neck and the Ship lying still observe diligently how those small winged animals fly with like velocity towards all parts of the Cabin how the fishes swim indifferently towards all sides and how the distilling drops all fall into the bottle placed underneath And casting any thing towards your friend you need not throw it with more force one way then another provided the distances be equal and leaping as the saying is with your feet closed you will reach as far one way as another Having observed all these particulars though no man doubteth that so long as the vessel stands still they ought to succeed in this manner make the Ship to move with what velocity you please for so long as the motion is uniforme and not fluctuating this way and that way you shall not discern any the least alteration in all the forenamed effects nor can you gather by any of them whether the Ship doth move or stand still In leaping you shall reach as far upon the floor as before nor for that the Ship moveth shall you make a greater leap towards the poop than towards the prow howbeit in the time that you staid in the Air the floor under your feet shall have run the contrary way to that of your jump and throwing any thing to your companion you shall not need to cast it with more strength that it may reach him if he shall be towards the prow and you towards the poop then if you stood in a contrary situation the drops shall all distill as before into the inferiour bottle and not so much as one shall fall towards the poop albeit whil'st the drop is in the Air the Ship shall have run many feet the Fishes in their water shall not swim with more trouble towards the fore-part than towards the hinder part of the tub but shall with equal velocity make to the bait placed on any side of the tub and lastly the flies and gnats shall continue their flight indifferently towards all parts nor shall they ever happen to be driven together towards the side of the Cabbin next the prow as if they were wearied with following the swift course of the Ship from which through their suspension in the Air they had been long separated and if burning a few graines of incense you make a little smoke you shall see it ascend on high and there in manner of a cloud suspend it self and move indifferently not inclining more to one side than another and of this correspondence of effects the cause is for that the Ships motion is common to all the things contained in it and to the Air also I mean if those things be shut up in the Cabbin but in case those things were above deck in the open Air and not obliged to follow the course of the Ship differences more or lesse notable would be observed in some of the fore-named effects and there is no doubt but that the smoke would stay behind as much as the Air it self the flies also and the gnats being hindered by the Air would not be able to follow the motion of the Ship if they were separated at any distance from it But keeping neer thereto because the Ship it self as being an unfractuous Fabrick carrieth along with it part of its neerest Air they would follow the said Ship without any pains or difficulty And for the like reason we see sometimes in riding post that the troublesome flies and hornets do follow the horses flying sometimes to one sometimes to another part of the body but in the falling drops the difference would be very small and in the salts and projections of grave bodies altogether imperceptible SAGR. Though it came not into my thoughts to make triall of these observations when I was at Sea yet am I confident that they will succeed in the same manner as you have related in confirmation of which I remember that being in my Cabbin I have asked an hundred times whether the Ship moved or stood still and sometimes I have imagined that it moved one way when it steered quite another way I am therefore as hitherto satisfied and convinced of the nullity of all those experiments that have been produced in proof of the negative part There now remains the objection founded upon that which experience shews us namely that a swift Vertigo or whirling about hath a faculty to extrude and disperse the matters adherent to the machine that turns round whereupon many were of opinion and Ptolomy amongst the rest that if the Earth should turn round with so great velocity the stones and creatures upon it should be tost into the Skie and that there could not be a morter strong enough to fasten buildings so to their foundations but that they would likewise suffer a like extrusion SALV Before I come to answer this objection I cannot but take notice of that which I have an hundred times observed and not without laughter to come into the minds of most men so soon as ever they hear mention made of this motion of the Earth which is believed by them so fixt and immoveable that they not only never doubted of that rest but have ever strongly believed that all other men aswell as they have held it to be created immoveable and so to have continued through all succeeding ages and being setled in this perswasion they stand amazed to hear that any one should grant it motion as if after that he had held it to be immoveable he had fondly thought it to commence its motion then and not till then when Pythagoras or whoever
worth than the wool of a goat and whereas our argumentations should continually be conversant about serious and weighty points we consume our time in frivolous and impertinent wranglings Let us call to minde I pray you that the search of the worlds constitution is one of the greatest and noblest Problems that are in nature and so much the greater inasmuch as it is directed to the resolving of that other to wit of the cause of the Seas ebbing and flowing enquired into by all the famous men that have hitherto been in the world and possibly found out by none of them Therefore if we have nothing more remaining for the full confutation of the argument taken from the Earths vertigo which was the last alledged to prove its immobility upon its own centre let us passe to the examination of those things that are alledged for and against the Annual Motion SAGR. I would not have you Salviatus measure our wits by the scale of yours you who use to be continually busied about the sublimest contemplations esteem those notions frivolous and below you which we think matters worthy of our profoundest thoughts yet sometimes for our satisfaction do not disdain to stoop so low as to give way a little to our curiosity As to the refutation of the last argument taken from the extrusions of the diurnal vertigo far less than what hath been said would have given me satisfaction and yet the things superfluously spoken seemed to me so ingenious that they have been so far from wearying my fancy as that they have by reason of their novelty entertained me all along with so great delight that I know not how to desire greater Therefore if you have any other speculation to add produce it for I as to my own particular shall gladly hearken to it SALV I have always taken great delight in those things which I have had the fortune to discover and next to that which is my chief content I find great pleasure in imparting them to some friends that apprehendeth and seemeth to like them Now in regard you are one of these slacking a little the reins of my ambition which is much pleased when I shew my self more perspicacious than some other that hath the reputation of a sharp sight I will for a full and true measure of the past dispute produce another fallacy of the Sectators of Ptolomey and Aristotle which I take from the argument alledged SAGR. See how greedily I wait to hear it SALV We have hitherto over-passed and granted to Ptolomey as an effect indubitable that the extrusion of the stone proceeding from the velocity of the wheel turn'd round upon its centre the cause of the said extrusion encreaseth in proportion as the velocity of the vertigo or whirling is augmented from whence it was inferred that the velocity of the Earth's vertigo being very much greater than that of any machin whatsoever that we can make to turn round artificially the extrusion of stones of animals c. would consequently be far more violent Now I observe that there is a great fallacy in this discourse in that we do compare these velocities indifferently and absolutely to one another It 's true that if I compare the velocities of the same wheel or of two wheels equal to each other that which shall be more swiftly turn'd round shall extrude the stone with greater violence and the velocity encreasing the cause of the projection shall likewise encrease but when the velocity is augmented not by encreasing the velocity in the same wheel which would be by causing it to make a greater number of revolutions in equal times but by encreasing the diameter and making the wheel greater so as that the conversion taking up the same time in the lesser wheel as in the greater the velocity is greater onely in the bigger wheel for that its circumference is bigger there is no man that thinketh that the cause of the extrusion in the great wheel will encrease according to the proportion of the velocity of its circumference to the velocity of the circumference of the other lesser wheel for that this is most false as by a most expeditious experiment I shall thus grosly declare We may sling a stone with a stick of a yard long farther than we can do with a stick six yards long though the motion of the end of the long stick that is of the stone placed in the slit thereof were more than double as swift as the motion of the end of the other shorter stick as it would be if the velocities were such that the lesser stick should turn thrice round in the time whilst the greater is making one onely conversion SAGR. This which you tell me Salviatus must I see needs succeed in this very manner but I do not so readily apprehend the cause why equal velocities should not operate equally in extruding projects but that of the lesser wheel much more than the other of the greater wheel therefore I intreat you to tell me how this cometh to pass SIMP Herein Sagredus you seem to differ much from your self for that you were wont to penetrate all things in an instant and now you have overlook'd a fallacy couched in the experiment of the stick which I my self have been able to discover and this is the different manner of operating in making the projection one while with the short sling and another while with the long one for if you will have the stone fly out of the slit you need not continue its motion uniformly but at such time as it is at the swiftest you are to stay your arm and stop the velocity of the stick whereupon the stone which was in its swiftest motion flyeth out and moveth with impetuosity but now that stop cannot be made in the great stick which by reason of its length and flexibility doth not entirely obey the check of the arm but continueth to accompany the stone for some space and holdeth it in with so much less force and not as if you had with a stiff sling sent it going with a jerk for if both the sticks or slings should be check'd by one and the same obstacle I do believe they would fly aswell out of the one as out of the other howbeit their motions were equally swift SAGR. With the permission of Salviatus I will answer something to Simplicius in regard he hath addressed himself to me and I say that in his discourse there is somewhat good and somewhat bad good because it is almost all true bad because it doth not agree with our case Truth is that when that which carrieth the stones with velocity shall meet with a check that is immoveable they shall fly out with great impetuosity the same effect following in that case which we see dayly to fall out in a boat that running a swift course runs a-ground or meets with some sudden stop for all those in the boat being surprized stumble forwards
Stars SALV Perhaps he is the same with the Author of the Book called Anti-Tycho SIMP He is the very same but the confutation of the new Stars is not in his Anti-Tycho onely so far as he proveth that they were not prejudicial to the inalterability and ingenerability of the Heavens as I told you before but after he had published his Anti-Tycho having found out by help of the Parallaxes a way to demonstrate that they also are things elementary and contained within the concave of the Moon he hath writ this other Book de tribus novis Stellis c. and therein also inserted the Arguments against Copernicus I have already shewn you what he hath written touching these new Stars in his Anti-Tycho where he denied not but that they were in the Heavens but he proved that their production altered not the inalterability of the Heavens and that he did with a Discourse purely philosophical in the same manner as you have already heard And I then forgot to tell you how that he afterwards did finde out a way to remove them out of the Heavens for he proceeding in this confutation by way of computations and parallaxes matters little or nothing at all understood by me I did not mention them to you but have bent all my studies upon these arguments against the motion of the Earth which are purely natural SALV I understand you very well and it will be convenient after we have heard what he hath to say against Copernicus that we hear or see at least the manner wherewith he by way of Parallaxes proveth those new stars to be elementary which so many famous Astronomers constitute to be all very high and amongst the stars of the Firmament and as this Author accomplisheth such an enterprize of pulling the new stars out of heaven and placing them in the elementary Sphere he shall be worthy to be highly exalted and transferred himself amongst the stars or at least that his name be by fame eternâ—â—ed amongst them Yet before we enter upon this let us hear what he alledgeth against the opinion of Copernicus and do you begin to recite his Arguments SIMP It will not be necessary that we read them ad verbum because they are very prolix but I as you may see in reading them several times attentively have marked in the margine those words wherein the strength of his arguments lie and it will suffice to read them The first Argument beginneth here Et primo si opinio Copernici recipiatur Criterium naturalis Philosophiae ni prorsus tollatur vehementer salâ—em labefactari videtur In our Idiom thus And first if Copernicus his opinion be imbraced the Criterium of natural Philosophy will be if not wholly subverted yet at least extreamly shaken Which according to the opinion of all the sects of Philosophers requireth that Sense and Experience be our guides in philosophating But in the Copernican position the Senses are greatly deluded whil'st that they visibly discover neer at hand in a pure Medium the gravest bodies to descend perpendicularly downwards never deviating a single hairs breadth from rectitude and yet according to the opinion of Copernicus the sight in so manifest a thing is deceived and that motion is not reall straight but mixt of right and circular SALV This is the first argument that Aristotle Ptolomy and all their followers do produce to vvhich we have abundantly answered and shewn the Paralogisme and with sufficient plainnesse proved that the motion in common to us and other moveables is as if there were no such thing but because true conclusions meet with a thousand accidents that confirme them I vvill with the favour of this Philosopher adde something more and you Simplicius personating him answer me to vvhat I shall ask you And first tell me vvhat effect hath that stone upon you which falling from the top of the Tower is the cause that you perceive that motion for if its fall doth operate upon you neither more nor lesse than its standing still on the Towers top you doubtlesse could not discern its descent or distinguish its moving from its lying still SIMP I comprehend its moving in relation to the Tower for that I see it one while just against such a mark in the said Tower and another while against another lower and so successively till that at last I perceive it arrived at the ground SALV Then if that stone were let fall from the tallons of an Eagle flying and should descend thorow the simple invisible Air and you had no other object visible and stable wherewith to make comparisons to that you could not perceive its motion SIMP No nor the stone it self for if I would see it when it is at the highest I must raise up my head and as it descendeth I must hold it lower and lower and in a word must continually move either that or my eyes following the motion of the said stone SALV You have novv rightly answered you knovv then that the stone lyeth still vvhen without moving your eye you alwayes see it before you and you know that it moveth when for the keeping it in sight you must move the organ of sight the eye So then vvhen ever without moving your eye you continually behold an object in the self same aspect you do alvvays judge it immoveable SIMP I think it must needs be so SALV Novv fancy your self to be in a ship and to have fixed your eye on the point of the Sail-yard Do you think that because the ship moveth very fast you must move your eye to keep your sight alvvayes upon the point of the Sail-yard and to follow its motion SIMP I am certain that I should need to make no change at all and that not only in the sight but if I had aimed a Musket at it I should never have need let the ship move how it vvill to stir it an hairs breadth to keep it full upon the same SALV And this happens because the motion which the Ship conferreth on the Sail-yard it conferreth also upon you and upon your eye so that you need not stir it a jot to behold the top of the Sail-yard and consequently it vvill seem to you immoveaable Now this Discourse being applied to the revolution of the Earth and to the stone placed in the top of the Tower in which you cannot discern any motion because that you have that motion vvhich is necessary for the following of it in common with it from the Earth so that you need not move your eye When again there is conferred upon it the motion of descent which is its particular motion and not yours and that it is intermixed with the circular that part of the circular which is common to the stone and to the eye continueth to be imperceptible and the right onely is perceived for that to the perception of it you must follow it with your eye looking lower and lower I wish for
happen to me in the present Probleme for being desirous to assure my self by some other accident whether the reason of the Proposition by me found were true namely whether the substance of the Magnet were really much lesse continuate than that of Iron or of Steel I made the Artists that work in the Gallery of my Lord the Grand Duke to smooth one side of that piece of Magnet which formerly was yours and then to polish and burnish it upon which to my satisfaction I found what I desired For I discovered many specks of colour different from the rest but as splendid and bright as any of the harder sort of stones the rest of the Magnet was polite but to the tact onely not being in the least splendid but rather as if it were smeered over with foot and this was the substance of the Load-stone and the shining part was the fragments of other stones intermixt therewith as was sensibly made known by presenting the face thereof to filings of Iron the which in great number leapt to the Load-stone but not so much as one grain did stick to the said spots which were many some as big as the fourth part of the nail of a mans finger others somewhat lesser the least of all very many and those that were scarce visible almost innumerable So that I did assure my self that my conjecture was true when I first thought that the substance of the Magnet was not close and compact but porous or to say better spongy but with this difference that whereas the sponge in its cavities and little cels conteineth Air or Water the Magnet hath its pores full of hard and heavy stone as appears by the exquisite lustre which those specks receive Whereupon as I have said from the beginning applying the surface of the Iron to the superficies of the Magnet the minute particles of the Iron though perhaps more continuate than these of any other body as its shining more than any other matter doth shew do not all nay but very few of them incounter pure Magnet and the contacts being few the union is but weak But because the cap of the Load-stone besides the contact of a great part of its superficies invests its self also with the virtue of the parts adjoyning although they touch not that side of it being exactly smoothed to which the other face in like manner well polisht of the Iron to be attracted is applyed the contract is made by innumerable minute particles if not haply by the infinite points of both the superficies whereupon the union becometh very strong This observation of smoothing the surfaces of the Irons that are to touch came not into the thoughts of Gilbert for he makes the Irons convex so that their contact is very small and thereupon it cometh to passe that the tenacity wherewith those Irons conjoyn is much lesser SAGR. I am as I told you before little lesse satisfied with this reason that if it were a pure Geometrical Demonstration and because we speak of a Physical Problem I believe that also Simplicius will find himself satisfied as far as natural science admits in which he knows that Geometrical evidence is not to be required SIMP I think indeed that Salviatus with a fine circumlocution hath so manifestly displayed the cause of this effect that any indifferent wit though not verst in the Sciences may apprehend the same but we confining our selves to the terms of Art reduce the cause of these and other the like natural effects to Sympathy which is a certain agreemet and mutual appetite which ariseth between things that are semblable to one another in qualities as likewise on the contrary that hatred enmity for which other things shun abhor one another we call Antipathy SAGR. And thus with these two words men come to render reasons of a great number of accidents and effects which we see not without admiration to be produced in nature But this kind of philosophating seems to me to have great sympathy with a certain way of Painting that a Friend of mine used who writ upon the Tele or Canvasse in chalk here I will have the Fountain with Diana and her Nimphs there certain Hariers in this corner I will have a Hunts-man with the Head of a Stag the rest shall be Lanes Woods and Hills and left the remainder for the Painter to set forth with Colours and thus he perswaded himself that he had painted the Story of Acteon when as he had contributed thereto nothing of his own more than the names But whether are we wandred with so long a digression contrary to our former resolutions I have almost forgot what the point was that we were upon when we fell into this magnetick discourse and yet I had something in my mind that I intended to have spoken upon that subject SALV We were about to demonstrate that third motion ascribed by Copernicus to the Earth to be no motion but a quiescence and maintaining of it self immutably directed with its determinate parts towards the same determinate parts of the Universe that is a perpetual conservation of the Axis of its diurnal revolution parallel to it self and looking towards such and such fixed stars which most constant position we said did naturally agree with every librated body suspended in a fluid and yielding medium which although carried about yet did it not change directionin respect of things external but onely seemed to revolve in its self in respect of that which carryed it round and to the vessel in which it was transported And then we added to this simple and natural accident the magnetick virtue whereby the self Terrestrial Globe might so much the more constantly keep it immutable SAGR. Now I remember the whole businesse and that which then came into my minde which I would have intimated was a certain consideration touching the scruple and objection of Simplicius which he propounded against the mobility of the Earth taken from the multiplicity of motions impossible to be assigned to a simple body of which but one sole and simple motion according to the doctrine of Aristotle can be natural and that which I would have proposed to consideration was the Magnet to which we manifestly see three motions naturally to agree one towards the centre of the Earth as a Grave the second is the circular Horizontal Motion whereby it restores and conserves its Axis towards determinate parts of the Universe and the third is this newly discovered by Gilbert of inclining its Axis being in the plane of a Meridian towards the surface of the Earth and this more and lesse according as it shall be distant from the Equinoctial under which it is parallel to the Axis of the Earth Besides these three it is not perhaps improbable but that it may have a fourth of revolving upon its own Axis in case it were librated and suspended in the air or other fluid and yielding Medium so that
the extreams Now my Masters that which the Bark doth in respect of the water by it contained and that which the water contained doth in respect of the Bark its container is the self-same to an hair with that which the Mediterranean Vessel doth in respect of the waters in it contained and that which the waters contained do in respect of the Mediterranean Vessel their container It followeth now that we demonstrate how and in what manner it is true that the Mediterrane and all the other Straits and in a word all the parts of the Earth do all move with a motion notably uneven though no motion that is not regular and uniforme is thereby assigned to all the said Globe taken collectively SIMP This Proposition at first sight to me that am neither Geometrician nor Astronomer hath the appearance of a very great Paradox and if it should be true that the motion of the whole being regular that of the parts which are all united to their whole may be irregular the Paradox will overthrow the Axiome that affirmeth Eandem esse rationem totius partium SALV I will demonstrate my Paradox and leave it to your care Simplicius to defend the Axiome from it or else to reconcile them and my demonstration shall be short and familiar depending on the things largely handled in our precedent conferences without introducing the least syllable in favour of the flux and reflux We have said that the motions assigned to the Terrestrial Globe are two the first Annual made by its centre about the circumference of the Grand Orb under the Ecliptick according to the order of the Signes that is from West to East the other made by the said Globe revolving about its own centre in twenty four hours and this likewise from West to East though about an Axis somewhat inclined and not equidistant from that of the Annual conversion From the mixture of these two motions each of it self uniform I say that there doth result an uneven and deformed motion in the parts of the Earth Which that it may the more easily be understood I will explain by drawing a Scheme thereof And first about the centre A in Fig. 1. of this Dialogue I will describe the circumference of the Grand Orb B C in which any point being taken as B about it as a centre we will describe this lesser circle D E F G representing the Terrestrial Globe the which we will suppose to run thorow the whole circumference of the Grand Orb with its centre B from the West towards the East that is from the part B towards C and moreover we will suppose the Terrestrial Globe to turn about its own centre B likewise from West to East that is according to the succession of the points D E F G in the space of twenty four hours But here we ought carefully to note that a circle turning round upon its own centre each part of it must at different times move with contrary motions the which is manifest considering that whilst the parts of the circumference about the point D move to the left hand that is towards E the opposite parts that are about F approach to the right hand that is towards G so that when the parts D shall be in F their motion shall be contrary to what it was before when it was in D. Furthermore the same time that the parts E descend if I may so speak towards F those in G ascend towards D. It being therefore presupposed that there are such contrarieties of motions in the parts of the Terrestrial Surface whilst it turneth round upon its own centre it is necessary that in conjoyning this Diurnal Motion with the other Annual there do result an absolute motion for the parts of the said Terrestrial Superficies one while very accelerate and another while as slow again The which is manifest considering first the parts about D the absolute motion of which shall be extream swift as that which proceedeth from two motions made both one way namely towards the left hand the first of which is part of the Annual Motion common to all the parts of the Globe the other is that of the said point D. carried likewise to the left by the Diurnal Revolution so that in this case the Diurnal motion increaseth and accelerateth the Annual The contrary to which happeneth in the opposite part F which whilst it is by the common annual motion carried together with the whole Globe towards the left it happeneth to be carried by the Diurnal conversion also towards the right so that the Diurnal motion by that means detracteth from the Annual whereupon the absolute motion resulting from the composition of both the other is much retarded Again about the points E and G the absolute motion becometh in a manner equal to the simple Annual one in regard that little or nothing increaseth or diminisheth it as not tending either to the left hand or to the right but downwards and upwards We will conclude therefore that like as it is true that the motion of the whole Globe and of each of its parts would be equal and uniforme in case they did move with one single motion whether it were the meer Annual or the single Diurnal Revolution so it is requisite that mixing those two motions together there do result thence for the parts of the said Globe irregular motions one while accelerated and another while retarded by means of the additions or substractions of the Diurnal conversion from the annual circulation So that if it be true and most true it is as experience proves that the acceleration and retardation of the motion of the Vessel makes water contained therein to run to and again the long wayes of it and to rise and fall in its extreames who will make scruple of granting that the said effect may nay ought to succeed in the Sea-waters contained within their Vessels subject to such like alterations and especially in those that distend themselves long-wayes from West to East which is the course that the motion of those same Vessels steereth Now this is the most potent and primary cause of the ebbing and flowing without the which no such effect would ensue But because the particular accidents are many and various that in several places and times are observed which must of necessity have dependance on other different concomitant causes although they ought all to have connexion with the primary therefore it is convenient that we propound and examine the several accidents that may be the causes of such different effects The first of which is that when ever the water by means of a notable retardation or acceleration of the motion of the Vessel its container shall have acquired a cause of running towards this or that extream and shall be raised in the one and abated in the other it shall not neverthelesse continue for any time in that state when once the primary cause
the Isles of Corsica and Sardinnia and in the Strands of Rome and Ligorne where it exceeds not half a foot we shall understand also why on the contrary where the risings and fallings are small the courses and recourses are great I say it is an easie thing to understand the causes of these accidents seeing that we meet with many manifest occurrences of the same nature in every kind of Vessel by us artificially composed in which the same effects are observed naturally to follow upon our moving it unevenly that is one while faster and another while flower Moreover considering in the fifth place that the same quantity of Water being moved though but gently in a spatious Channel comming afterwards to go through a narrow passage will of necessity run with great violence we shall not finde it hard to comprehend the cause of the great Currents that are made in the narrow Channel that separateth Calabria from Sicilia for that all the Waters that by the spaciousnesse of the Isle and by the Ionick Gulph happens to be pent in the Eastern part of the Sea though it do in that by reason of its largeness gently descend towards the West yet neverthelesse in that it is pent up in the Bosphorus it floweth with great violence between Scilla and Caribdis and maketh a great agitation Like to which and much greater is said to be betwixt Africa and the great Isle of St. Lorenzo where the Waters of the two vast Seas Indian and Ethiopick that lie round it must needs be straightned into a lesse Channel between the said Isle and the Ethiopian Coast. And the Currents must needs be very great in the Straights of Megallanes which joyne together the vast Oceans of Ethiopia and Del Zur called also the Pacifick Sea It follows now in the sixth place that to render a reason of some more abstruse and incredible accidents which are observed upon this occasion we make a considerable reflection upon the two principal causes of ebbings and flowings afterwards compounding and mixing them together The first and simplest of which is as hath often been said the determinate acceleration and retardation of the parts of the Earth from whence the Waters have a determinate period put to their decursions towards the East and return towards the West in the time of twenty four hours The other is that which dependeth on the proper gravity of the Water which being once commoved by the primary cause seeketh in the next place to reduce it self to Aequilibrium with iterated reciprocations which are not determined by one sole and prefixed time but have as many varieties of times as are the different lengths and profundities of the receptacles and Straights of Seas and by what dependeth on this second principle they would ebbe and flow some in one hour others in two in four in six in eight in ten c. Now if we begin to put together the first cause which hath its set Period from twelve hours to twelve hours with some one of the secondary that hath its Period verb. grat from five hours to five hours it would come to passe that at sometimes the primary cause and secondary would accord to make impulses both one the same way and in this concurrency and as one may call it unanimous conspiration the flowings shall be great At other times it happening that the primary impulse doth in a certain manner oppose that which the secondary Period would make and in this contest one of the Principles being taken away that which the other would give will weaken the commotion of the Waters and the Sea will return to a very tranquil State and almost immoveable And at other times according as the two aforesaid Principles shall neither altogether contest nor altogether concur there shall be other kinds of alterations made in the increase and diminution of the ebbing and flowing It may likewise fall out that two Seas considerably great and which communicate by some narrow Channel may chance to have by reason of the mixtion of the two Principles of motion one cause to flow at the time that the other hath cause to move a contrary way in which case in the Channel whereby they disimbogue themselves into each other there do extraordinary conturbations insue with opposite and vortick motions and most dangerous boilings and breakings as frequent relations and experiences do assure us From such like discordant motions dependent not onely on the different positions and longitudes but very much also upon the different profundities of the Seas which have the said intercourse there do happen at sometimes different commotions in the Waters irregular and that can be reduced to no rules of observation the reasons of which have much troubled and alwayes do trouble Mariners for that they meet with them without seeing either impulse of winds or other eminent aereal alteration that might occasion the same of which disturbance of the Air we ought to make great account in other accidents and to take it for a third and accidental cause able to alter very much the observation of the effects depending on the secondary and more essential causes And it is not to be doubted but that impetuous windes continuing to blow for example from the East they shall retein the Waters and prohibit the reflux or ebbing whereupon the second and third reply of the flux or tide overtaking the former at the hours prefixed they will swell very high and being thus born up for some dayes by the strength of the Winds they shall rise more than usual making extraordinary inundations We ought also and this shall serve for a seventh Probleme to take notice of another cause of motion dependant on the great abundance of the Waters of great Rivers that discharge themselves into Seas of no great capacity whereupon in the Straits or Bosphori that communicate with those Seas the Waters are seen to run always one way as it happeneth in the Thracian Bosphorus below Constantinople where the water alwayes runneth from the Black-Sea towards the Propontis For in the said Black-Sea by reason of its shortnesse the principal causes of ebbing and flowing are but of small force But on the contrary very great Rivers falling into the same those huge defluxions of water being to passe and disgorge themselves by the the straight the course is there very notable and alwayes towards the South Where moreover we ought to take notice that the said Straight or Channel albeit very narrow is not subject to perturbations as the Straight of Scilla and Carybdis for that that hath the Black-Sea above towards the North and the Propontis the Aegean and the Mediterranean Seas joyned unto it though by a long tract towards the South but now as we have observed the Seas though of never so great length lying North and South are not much subject to ebbings and flowings but because the Sicilian Straight is situate between the parts of the Mediterrane distended
for a long tract or distance from West to East that is according to the course of the fluxes and refluxes therefore in this the agitations are very great and would be much more violent between Hercules Pillars in case the Straight of Gibraltar did open lesse and those of the Straight of Magellanes are reported to be extraordinary violent This is what for the present cometh into my mind to say unto you about the causes of this first period diurnal of the Tide and its various accidents touching which if you have any thing to offer you may let us hear it that so we may afterwards proceed to the other two periods monethly and annual SIMP In my opinion it cannot be denied but that your discourse carrieth with it much of probability arguing as we say ex suppositione namely granting that the Earth moveth with the two motions assigned it by Copernicus but if that motion be disproved all that you have said is vain and insignificant and for the disproval of that Hypothesis it is very manifestly hinted by your Discourse it self You with the supposition of the two Terrestrial motions give a reason of the ebbing and flowing and then again arguing circularly from the ebbing and flowing draw the reason and confirmation of those very motions and so proceeding to a more specious Discourse you say that the Water as being a fluid body and not tenaciously annexed to the Earth is not constrained punctually to obey every of its motions from which you afterwards infer its ebbing and flowing Now I according to your own method argue the quite contrary and say the Air is much more tenuous and fluid than the Water and lesse annexed to the Earths superficies to which the Water if it be for nothing else yet by reason of its gravity that presseth down upon the same more than the light Air adhereth therefore the Air is much obliged to follow the motions of the Earth and therefore were it so that the Earth did move in that manner we the inhabitants of it and carried round with like velocity by it ought perpetually to feel a Winde from the East that beateth upon us with intolerable force And that so it ought to fall out quotidian experience assureth us for if with onely riding post at the speed of eight or ten miles an hour in the tranquil Air the incountering of it with our face seemeth to us a Winde that doth not lightly blow upon us what should we expect from our rapid course of 800. or a thousand miles an hour against the Air that is free from that motion And yet notwithstanding we cannot perceive any thing of that nature SALV To this objection that hath much of likelihood in it I reply that its true the Air is of greater tenuity and levity and by reason of its levity lesse adherent to the Earth than Water so much more grave and bulky but yet the consequence is false that you infer from these qualities namely that upon account of that its levity tenuity and lesse adherence to the Earth it should be more exempt than the Water from following the Terrestrial Motions so as that to us who absolutely pertake of of them the said exemption should be sensible and manifest nay it happeneth quite contrary for if you well remember the cause of the ebbing and flowing of the Water assigned by us consisteth in the Waters not following the unevennesse of the motion of its Vessel but retaining the impetus conceived before without diminishing or increasing it according to the precise rate of its diminishing or increasing in its Vessel Because therefore that in the conservation and retention of the impetus before conceived the disobedience to a new augmentation or diminution of motion consisteth that moveable that shall be most apt for such a retention shall be also most commodious to demonstrate the effect that followeth in consequence of that retention Now how much the Water is disposed to maintain such a conceived agitation though the causes cease that impress the same the experience of the Seas extreamly disturbed by impetuous Winds sheweth us the Billows of which though the Air be grown calm and the Wind laid for a long time after continue in motion As the Sacred Poet pleasantly sings Qual l'alto Egeo c. And that long continuing rough after a storm dependeth on the gravity of the water For as I have elsewhere said light bodies are much easier to be moved than the more grave but yet are so much the less apt to conserve the motion imparted when once the moving cause ceaseth Whence it comes that the Aire as being of it self very light and thin is easily mov'd by any very small force yet it is withall very unable to hold on its motion the Mover once ceasing Therefore as to the Aire which environs the Terrestrial Globe I would fay that by reason of its adherence it is no lesse carried about therewith then the Water and especially that part which is contained in its vessels which vessels are the valleys enclosed with Mountains And we may with much more reason affirm that this same part of the Air is carried round and born forwards by the rugged parts of the Earth than that the higher is whirl'd about by the motion of the Heavens as ye Peripateticks maintain What hath been hitherto spoken seems to me a sufficient answer to the allegation of Simplitius yet nevertheless with a new instance and solution founded upon an admirable experiment I will superabundantly satisfie him and confirm to Sagredus the mobility of the Earth I have told you that the Air and in particular that part of it which ascendeth not above the tops of the highest Mountains is carried round by the uneven parts of the Earths surface from whence it should seem that it must of consequence come to passe that in case the superficies of the Earth were not uneven but smooth and plain no cause would remain for drawing the Air along with it or at least for revolving it with so much uniformity Now the surface of this our Globe is not all craggy and rugged but there are exceeding great tracts very even to wit the surfaces of very vast Seas which being also far remote from the continuate ledges of Mountains which environ it seem to have no faculty of carrying the super-ambient Air along therewith and not carrying it about we may perceive what will of consequence ensue in those places SIMP I was about to propose the very same difficulty which I think is of great validity SALV You say very well Simplicius for from the not finding in the Air that which of consequence would follow did this our Globe move round you argue its immoveablenesse But in case that this which you think ought of necessary consequence to be found be indeed by experience proved to be so will you accept it for a sufficient testimony and an argument for the mobility of
scarce kist her Maid yet nevertheless to give you my sudden thoughts I shall tell you That of those effects by you recounted and particularly the last there may in my judgement very sufficient Reasons be given without the Earths mobility by the mobility of the Heavens onely never introducing any novelty more than the inversion of that which you your self propose unto us It hath been received by the Peripatetick Schools that the Element of Fire and also a great part of the Aire is carried about according to the Diurnal conversion from East to West by the contact of the Concave of the Lunar Orb as by the Vessel their container Now without going out of your track I will that we determine the Quantity of the Aire which partaketh of that motion to distend so low as to the Tops of the highest Hills and that likewise they would reach to the Earth if those Mountains did not impede them which agreeth with what you say For as you affirm the Air which is invironed by ledges of Mountains to be carried about by the asperity of the moveable Earth we on the contrary say That the whole Element of Air is carried about by the motion of Heaven that part only excepted which lyeth below those bodies which is hindred by the asperity of the immoveable Earth And whereas you said That in case that asperity should be removed the Air would also cease to be whirld about we may say That the said asperity being removed the whole Aire would continue its motion Whereupon because the surfaces of spacious Seas are smooth and even the Airs motion shall continue upon those alwaies blowing from the East And this is more sensibly perceived in Climates lying under the Line and within the Tropicks where the motion of Heaven is swifter and like as that Celestial motion is able to bear before it all the Air that is at liberty so we may very rationally affirm that it contributeth the same motion to the Water moveable as being fluid and not connected to the immobility of the Earth And with so much the more confidence may we affirm the same in that by your confession that motion ought to be very small in resect of the efficient Cause which begirting in a natural day the whole Terrestrial Globe passeth many hundreds of miles an hour and especially towards the Equinoctial whereas in the currents of the open Sea it moveth but very few miles an hour And thus the voiages towards the West shall come to be commodious and expeditious not onely by reason of the perpetual Eastern Gale but of the course also of the Waters from which course also perhaps the Ebbing and Flowing may come by reason of the different scituation of the Terrestrial Shores against which the Water coming to beat may also return backwards with a contrary motion like as experience sheweth us in the course of Rivers for according as the Water in the unevenness of the Banks meeteth with some parts that stand out or make with their Meanders some Reach or Bay here the Water turneth again and is seen to retreat back a considerable space Upon this I hold That of those effects from which you argue the Earths mobility and alledge it as a cause of them there may be assigned a cause sufficiently valid retaining the Earth stedfast and restoring the mobility of Heaven SALV It cannot be denied but that your discourse is ingenious hath much of probability I mean probability in appearance but not in reality existence It consisteth of two parts In the first it assignes a reason of the continual motion of the Eastern Winde and also of a like motion in the Water In the second It would draw from the same Sourse the cause of the Ebbing and Flowing The first part hath as I have said some appearance of probability but yet extreamly less then that which we take from the Terrestrial motion The second is not onely wholly improbable but altogether impossible and false And coming to the first whereas it is said that the Concave of the Moon carrieth about the element of Fire and the whole Air even to the tops of the higher Mountains I answer first that it is dubious whether there be any element of Fire But suppose there be it is much doubted of the Orbe of the Moon as also of all the rest that is Whether there be any such solid bodies and vast or elss Whether beyond the Air there be extended a continuate expansion of a substance of much more tenuity and purity than our Air up and down which the Planets go wandring as now at last a good part of those very Phylosophers begin to think But be it in this or in that manner there is no reason for which the Fire by a simple contract to a superficies which you your self grant to be smooth and terse should be according to its whole depth carried round in a motion different from its natural inclination as hath been defusely proved and with sensible reasons demonstrated by Il Saggiatore Besides the other improbability of the said motions transfusing it self from the subtilest Fire throughout the Air much more dense and from that also again to the Water But that a body of rugged and mountainous surface by revolving in it self should carry with it the Air contiguous to it and against which its promontaries beat is not onely probable but necessary and experience thereof may be daily seen though without seeing it I believe that there is no judgement that doubts thereof As to the other part supposing that the motion of Heaven did carry round the Air and also the Water yet would that motion for all that have nothing to do with the Ebbing and Flowing For being that from one onely and uniform cause there can follow but one sole and uniform effect that which should be discovered in the Water would be a continuate and uniform course from East to West and in that a Sea onely which running compass environeth the whole Globe But in determinate Seas such as is the Mediterrane shut up in the East there could be no such motion For if its Water might be driven by the course of Heaven towards the West it would have been dry many ages since Besides that our Water runneth not onely towards the West But returneth backwards towards the East and that in ordinal Periods And whereas you say by the example of Rivers that though the course of the Sea were Originally that onely from East to West yet nevertheless the different Position of the Shores may make part of the Water regurgitate and return backwards I grant it you but it is necessary that you take notice my Simplicius that where the Water upon that account returneth backwards it doth so there perpetually and where it runneth straight forwards it runneth there alwayes in the same manner for so the example of the Rivers shewes you But in the case
obscurity that you see SAGR. Rather in that which I do no not see for hitherto I comprehend nothing at all SALV I have already foretold it Neverthelesse we will try whether by drawing a Diagram thereof we can give some small light to the same though indeed it might better be set forth by solid bodies than by bare Schemes yet we will help our selves with Perspective and fore-shortning Let us draw therefore as before the circumference of the Grand Orb as in Fig. 4. in which the point A is understood to be one of the Solstitials and the diameter AP the common Section of the Solstitial Colure and of the plane of the Grand Orb or Ecliptick and in that same point A let us suppose the centre of the Terrestrial Globe to be placed the Axis of which CAB inclined upon the Plane of the Grand Orb falleth on the plane of the said Colure that passeth thorow both the Axis of the Equinoctial and of the Ecliptick And for to prevent confusion let us only draw the Equinoctial circle marking it with these characters DGEF the common section of which with the plane of the grand Orb let be the line DE so that half of the said Equinoctial DFE will remain inclined below the plane of the Grand Orb and the other half DGE elevated above Let now the Revolution of the said Equinoctial be made according to the order of the points DGEF and the motion of the centre from A towards E. And because the centre of the Earth being in A the Axis CB which is erect upon the diameter of the Equinoctial DE falleth as hath been said in the Solstitial Colure the common Section of which and of the Grand Orb is the diameter PA the said line PA shall be perpendicular to the same DE by reason that the Colure is erect upon the grand Orb and therefore the said DE shall be the Tangent of the grand Orb in the point A. So that in this Position the motion of the Centre by the arch AE that is of one degree every day differeth very little yea is as if it were made by the Tangent DAE And because by means of the diurnal motion the point D carried about by G unto E encreaseth the motion of the Centre moved almost in the same line DE as much as the whole diameter DE amounts unto and on the other side diminisheth as much moving about the other semicircle EFD The additions and subductions in this place therefore that is in the time of the solstice shall be measured by the whole diameter DE. Let us in the next place enquire Whether they be of the same bigness in the times of the Equinoxes and transporting the Centre of the Earth to the point I distant a Quadrant of a Circle from the point A. Let us suppose the said Equinoctial to be GEFD its common section with the grand Orb DE the Axis with the same inclination CB but the Tangent of the grand Orb in the point I shall be no longer DE but another which shall cut that at right Angles and let it be this marked HIL according to which the motion of the Centre I shall make its progress proceeding along the circumference of this grand Orb. Now in this state the Additions and Substractions are no longer measured by the diameter DE as before was done because that diameter not distending it self according to the line of the annual motion HL rather cutting it at right angles those terms DE do neither add nor substract any thing but the Additions and Substractons are to be taken from that diameter that falleth in the plane that is errect upon the plane of the grand Orb and that intersects it according to the line HL which diameter in this case shall be this GF and the Adjective if I may so say shall be that made by the point G about the semicircle GEF and the Ablative shall be the rest made by the other semicircle FDG Now this diameter as not being in the same line HL of the annual motion but rather cutting it as we see in the point I the term G being elevated above and E depressed below the plane of the grand Orb doth not determine the Additions and Substractions according to its whole length but the quantity of those first ought to be taken from the part of the line HL that is intercepted between the perpendiculars drawn upon it from the terms GF namely these two GS and FV So that the measure of the additions is the line SV lesser then GF or then DE which was the measure of the additions in the Solstice A. And so successively according as the centre of the Earth shall be constituted in other points of the Quadrant AI drawing the Tangents in the said points and the perpendiculars upon the same falling from the terms of the diameters of the Equinoctial drawn from the errect planes by the said Tangents to the plane of the grand Orb the parts of the said Tangents which shall continually be lesser towards the Equinoctials and greater towards the Solstices shall give us the quantities of the additions and substractions How much in the next place the least additions differ from the greatest is easie to be known because there is the same difference betwixt them as between the whole Axis or Diameter of the Sphere and the part thereof that lyeth between the Polar-Circles the which is less than the whole diameter by very near a twelfth part supposing yet that we speak of the additions and substractions made in the Equinoctial but in the other Parallels they are lesser according as their diameters do diminish This is all that I have to say upon this Argument and all perhaps that can fall under the comprehension of our knowledge which as you well know may not entertain any conclusions save onely those that are firm and constant such as are the three kinds of Periods of the ebbings and flowings for that they depend on causes that are invariablâ— simple and eternal But because that secondary and particular causes able to make many alterations intermix with these that are the primary and universal and these secondary causes being part of them inconstant and not to be observed as for example The alteration of Winds and part though terminate and fixed unobserved for their multiplicity as are the lengths of the Straights their various inclinations towards this or that part the so many and so different depths of the Waters who shall be able unless after very long observations and very certain relations to frame so expeditious Histories thereof as that they may serve for Hypotheses and certain suppositions to such as will by their combinations give adequate reasons of all the appearances and as I may say Anomalie and particular irregularities that may be discovered in the motions of the Waters I will content my self with advertising you that the accidental causes are in nature and are able to produce
many alterations for the more minute observations I remit them to be made by those that frequent several Seas and onely by way of a conclusion to this our conference I will propose to be considered how that the precise times of the fluxes and refluxes do not onely happen to be altered by the length of Straights and by the difference of depths but I believe that a notable alteration may also proceed from the comparing together of sundry tarcts of Sea different in greatness and in position or if you will inclination which difference happeneth exactly here in the Adriatick Gulph lesse by far than the rest of the Mediterrane and placed in so different an inclination that whereas that hath its bounds that incloseth it on the Eastern part as are the Coasts of Syria this is shut up in its more Westerly part and because the ebbings and flowings are much greater towards the extremities yea because the Seas risings and fallings are there onely greatest it may probably happen that the times of Flood at Venice may be the time of low Water in the other Sea which as being much greater and distended more directly from West to East cometh in a certain sort to have dominion over the Adriatick and therefore it would be no wonder in case the effects depending on the primary causes should not hold true in the times that they ought and that correspond to the periods in the Adriatick as it doth in the rest of the Mediterrane But these Particularities require long Observations which I neither have made as yet nor shall I ever be able to make the same for the future SAGR. You have in my opinion done enough in opening us the way to so lofty a speculation of which if you had given us no more than that first general Proposition that seemeth to me to admit of no reply where you declare very rationally that the Vessels containing the Sea-waters continuing stedfast it would be impossible according to the common course of Nature that those motions should follow in them which we see do follow and that on the other side granting the motions ascribed for other respects by Copernicus to the Terrestrial Globe these same alterations ought to ensue in the Seas if I say you had told us no more this alone in my judgment so far exceeds the vanities introduced by so many others that my meer looking on them makes me nauseate them and I very much admire that among men of sublime wit of which nevertheless there are not a few not one hath ever considered the incompatibility that is between the reciprocal motion of the Water contained and the immobility of the Vessel containing which contradiction seemeth to me now so manifest SALV It is more to be admired that it having come into the thoughts of some to refer the cause of the Tide to the motion of the Earth therein shewing a more than common apprehension they should in afterwards driving home the motion close with no side and all because they did not see that one simple and uniform motion as v. gr the sole diurnal motion of the Terrestrial Globe doth not suffice but that there is required an uneven motion one while accelerated and another while retarded for when the motion of the Vessels are uniforme the waters contained will habituate themselves thereto without ever making any alteration To say also as it is related of an ancient Mathematician that the motion of the Earth meeting with the motion of the Lunar Orb the concurrence of them occasioneth the Ebbing and Flowing is an absolute vanity not onely because it is not exprest nor seen how it should so happen but the falsity is obvious for that the Revolution of the Earth is not contrary to the motion of the Moon but is towards the same way So that all that hath been hitherto said and imagined by others is in my judgment altogether invalid But amongst all the famous men that have philosophated upon this admirable effect of Nature I more wonder at Kepler than any of the rest who being of a free and piercing wit and having the motion ascribed to the Earth before him hath for all that given his ear and assent to the Moons predominancy over the Water and to occult properties and such like trifles SAGR. I am of opinion that to these more spaculative persons the same happened that at present befalls me namely the not understanding the intricate commixtion of the three Periods Annual Monethly and Diurnal And how their causes should seem to depend on the Sun and on the Moon without the Suns or Moons having any thing to do with the Water a businesse for the full understanding of which I stand in need of a little longer time to consider thereof which the novelty and difficulty of it hath hitherto hindred me from doing but I despair not but that when I return in my solitude and silence to ruminate that which remaineth in my fancy not very well digested I shall make it my own We have now from these four dayes Discourse great attestations in favour of the Copernican Systeme amongst which these three taken the first from the Stations and Retrogradations of the Planets and from their approaches and recessions from the Earth the second from the Suns revolving in it self and from what is observed in its spots the third from the Ebbing and Flowing of the Sea do shew very rational and concluding SALV To which also haply in short one might adde a fourth and peradventure a fifth a fourth I say taken from the fixed stars seeing that in them upon exact observations those minute mutations appear that Copernicus thought to have been insensible There starts up at this instant a fifth novelty from which one may argue mobility in the Terrestrial Globe by means of that which the most Illustrious Signore Caesare of the noble Family of the Marsilii of Bologna and a Lyncean Academick discovereth with much ingenuity who in a very learned Tract of his sheweth very particularly how that he had observed a continual mutation though very slow in the Meridian line of which Treatise at length with amazement perused by me I hope he will communicate Copies to all those that are Students of Natures Wonders SAGR. This is not the first time that I have heard speak of the exquisite Learning of this Gentleman and of his shewing himself a zealous Patron of all the Learned and if this or any other of his Works shall come to appear in publique we may be aforehand assured that they will be received as things of great value SALV Now because it is time to put an end to our Discourses it remaineth that I intreat you that if at more leasure going over the things again that have been alledged you meet with any doubts or scruples not well resolved you will excuse my oversight as well for the novelty of the Notion as for the weaknesse of my wit as also
filched from the Ancients and somewhat altered 99 Aristotle his Arguments for the Earths Quiescence and Immobility 107 Aristotle were he alive would either refute his Adversaries Arguments or else would alter his Opinion 113 Aristotles first Argument against the Earths Motion is defective in two things 121 The Paralogisme of Aristotle and Ptolomy in supposing that for known which is in question 121 Aristotle admitteth that the Fire moveth directly upwards by Nature and round about by Participation 122 Aristotle and Ptolomy seem to confute the Earths Mobility against those who think that it having along time stood still began to move in the time of Pythagoras 168 Aristotle his errour in affirming falling Grave Bodies to move according to the proportion of their gravities 199 Aristotle his Demonstrations to prove the Earth is finite are all nullified by denying it to be moveable 294 Aristotle maketh that Point to be the Centre of the Universe about which all the Celestial Spheres do revolve 294 A question is put if Arist. were forced to receive one of two Propositions that make against his Doctrine which he would admit 294 Aristotle his Argument against the Ancients who held that the Earth was a Planet 344 Aristotle taxeth Plato of being over-studious of Geometry 361 Aristotle hâ—ldeth those Effects to be miraculous of which the Causes are unknown 384 ASTRONOMERS Astronomers confuted by Anti-Tycho 38 The principal Scope of Astronomers is to give a reason of Appearances and Phaenomena 308 Astronomers all agree that the greater Magnitudes of the Orbes is the cause of the tardity in their Conversions 331 Astronomers perhaps have not known what Appearances ought to follow upon the Annual Motion of the Earth 338 Astronomers having omitted to instance what alterations those are that may be derived from the Annual Motion of the Earth do thereby testifie that they never rightly understood the same 343 ASTRONOMICAL Astronomical Observations wrested by Anti-Tycho to his own purpose 39 Astronomical Instruments are very subject to errour 262 ASTRONOMY Astronomy restored by Copernicus upon the Suppositions of Ptolomy 308 Many things may remain as yet unobserved in Astronomy 415 AUCUPATORIAN An Aucupatorian Problem for shooting of Birds flying 157 AXIOME or Axiomes In the Axiome Frustra fit per plura c. the addition of aequae bene is super fluous 106 Three Axiomes that are supposed manifest 230 Certain Axiomes commonly admitted by all Philosophers 361 B BODY and Bodies Contraries that corrupt reside not in the same Body that corrupteth 30 GRAVE BODY If the Celestial Globe were perforated a Grave Body descending by that Bore would passe and ascend as far beyond the Centre as it did descend 203 The motion of Grave Bodies Vide Motion The Accelleration of Grave Bodies that descend naturally increaseth from moment to moment 205 We know no more who moveth Grave Bodies downwards than who moveth the Stars round nor know we any thing of these Courses more than the Names imposed on them by our selves 210 The great Masse of Grave Bodies being transferred out of their Place the seperated parts would follow that Masse 221 PENSILE BODY Every Pensile Body carried round in the Circumference of a Circle acquireth of it self a Motion in it self contrary to the same 362 CELESTIAL BODIES neither heavy nor light according to Aristotle 23 Celestial Bodies are Generable and Corruptible because they are Ingenerable and Incorruptible 29 Amongst Celest. Bodies there is no contrariety 29 Celestial Bodies touch but are not touched by the Elements 30 Rarity and Density in Celestial Bodies different from Rarity and Density in the Elements 30 Celestial Bodies designed to serve the Earth need no more but Motion and Light 45 Celestial Bodies want an interchangeable Operation on each other 46 Celestial Bodies alterable in their externe parts 46 Perfect Sphericity why ascribed to Celestial Bodies by Peripateticks 69 All Celestial Bodies have Gravity and Levity 493 ELEMENTARY BODIES Their propension to follow the Earth hath a limited Sphere of Activity 213 LIGHT BODIES easier to be moved than heavy but lesse apt to conserve the Motion 400 LUMINOUS BODIES Bodies naturally Luminous are different from those that are by nature Obscure 34 The reason why Luminous Bodies appear so much the more enlarged by how much they are lesser 304 Manifest Experience shews that the more Luminous Bodies do much more irradiate than the lesse Lucid. 306 SIMPLE BODYES have but one Simple Motion that agreeth with them 494 SPHERICAL BODIES In Spherical Bodies Deorsum is the Centre and Sursum the Cirference 479 BONES The ends of the Bones are rotund and why 232 BUONARRUOTTI Buonarruotti a Statuary of admirable ingenuity 86 C CANON A shameful Errour in the Argument taken from the Canon-Bullets falling from the Moons Concave 197 An exact Computation of the fall of the Canon-Bullet from the Moons Concave to the Centre of the Earth 198 CELESTIAL Celestial Substances that be Vnalterable and Elementary that be Alterable necessary in the opinion of Aristotle 2 CENTRE The Sun more probably in the Centre of the Vniverse than the Earth 22 Natural inclination of all the Globes of the World to go to their Centre 22 Grave Bodies may more rationally be affirmed to tend towards the Centre of the Earth than of the Vniverse 25 CHYMISTS Chymists interpret the Fables of Poets to be Secrets for making of Gold 93 CIRCLE and Circular It is not impossible with the Circumference of a small Circle few times revolved to measure and describe a line bigger than any great Circle whatsoever 222 The Circular Line perfect according to Aristotle and the Right imperfect and why 9 CLARAMONTIUS The Paralogisme of Claramontius 241 The Argument of Claramontius recoileth upon himself 245 The Method observed by Claramontius in consuting Astronomers and by Salviatus in refuting him 253 CLOUDS Clouds no lesse apt than the Moon to be illuminated by the Sun 73 CONCLUSION and Conclusions The certainty of the Conclusion helpeth by a resolutive Method to finde the Demonstration 37 The Book of Conclusioâ—s frequently mentioned was writ by Christopher Scheiner a Jesuit 195 323. CONTRARIES Contraries that corrupt reside not in the same Body that corrupteth 30 COPERNICAN Answers to the three first Objections against the Copernican System 303 The Copernican System difficul to be understood but easie to be effected 354 A plain Scheme representing the Copernican Systeme and its consequences 354 The proscribing of the Copernican Doctrine after so long a Tolleration and now that it is more than ever followed studied and confirmed would be an affront to Truth 444 The Copern System admirably agreeth with the Miracle of Joshuah in the Literal Sense 456 If Divines would admit of the Copernican System they might soon find out Expositions for all Scriptures that seem to make against it 459 The Copernican System rejected by many out of a devout respect to Scripture Authorities 461 The Copernican System more plainly asserted in Scripture than the Ptolomaick 469 COPERNICANS Copernicans are
supposed by the Authour Galileo to be perfectly Ordinate 10 The Sensible World 96 It hath not been hitherto proved by any whether the World be finite or infinite 293 If the Centre of the World be the same with that about which the Planets move the Sun and not the Earth is placed in it 295 WRITING Some Write what they understand not and therefore understand not what they Write 63 The Invention of Writing Stupendious above all others 88 Y YEAR The Years beginning and ending which Ptolomy and his Followers could never positively assign is exactly determined by the Copernican Hypothesis 469 THE END OF THE TABLE THE Ancient and Modern DOCTRINE OF Holy Fathers AND Iudicious Divines CONCERNING The rash citation of the Testimony of SACRED SCRIPTURE in Conclusions meerly Natural and that may be proved by Sensible Experiments and Necessary Demonstrations Written some years since to Gratifie The most SERENE CHRISTINA LOTHARINGA Arch-Dutchess of TVSCANY By GALILAEO GALILAEI A Gentleman of Florence and Chief Philosopher and Mathematician to His most Serene Highness the Grand DVKE And now rendred into English from the Italian BY THOMAS SALUSBURY Naturam Rerum invenire difficile ubi inveneris indicare in vulgus nefas Plato LONDON Printed by WILLIAM LEYBOURN 1661. TO Her most Serene HIGHNES THE Gran Duchess Mother SOme years since as Your most Serene Highness well knoweth I did discover many particulars in Heaven that had been unseen and unheard of untill this our Age which as well for their novelty as for certain consequences which depend upon them clashing with some Physical Propositions commonly received by the Schools did stir up against me no small number of such as professed the vulgar Philosophy in the Universities as if I had with my own hand newly placed these things in Heaven to obscure and disturb Nature and the Sciences who forgetting that the multitude of Truths contribute and concur to the investigation augmentation and establishment of the Arts and not to their diminution and destruction and at the same time shewing themselves more affectionate to their own Opinions than to Truth went about to deny and to disprove those Novelties of which their very sense had they but pleased to have intentsly beheld them would have rendered them thorowly assured And to this purpose they alledged sundry things and published certain Papers fraughted with vain discourses and which was a more gross errour interwoven with the attestations of the Sacred Scriptures taken from places by them not rightly understood and which did not any thing concern the point for which they were produced Into which errour perhaps they would not have run if they had but been advertised of a most profitable Document which S. Augustine giveth us concerning our proceeding warily in making positive determinations in points that are obscure and hard to be understood by the meer help of ratiocination where treating as we of a certain natural conclusion concerning Celestial Bodies he thus writes But now having evermore a respect to the moderation of pious Gravity we ought to believe nothing unadvisedly in a doubtful point lest we conceive a prejudice against that in favour to our Errour which Truth hereafter may discover to be no wise contrary to the Sacred Books either of the Old or New Testament It hath since come to pass that Time hath by degrees discovered to every one the truths before by me indicated and together with the truth of the fact a discovery hath been made of the difference of humours between those who simply and without passion did refuse to admit such like Phaenomena for true and those who to their incredulity had added some discomposed affection For as those who were better grounded in the Science of Astronomy and Natural Philosophy became satisfied upon my first intimation of the news so all those who stood not in the Negative or in doubt for any other reason but because it was an unlookt-for-Novelty and because they had not an occasion of seeing a sensible experiment thereof did by degrees come to satisfie themselves But those who besides the love they bore to to their first Errour have I know not what imaginary interess to render them disaffected not so much towards the things as towards the Author of them not being able any longer to deny them conceal themselves under an obstinate silence and being exasperated more than ever by that whereby those others were satisfied and convinced they divert their thoughts to other projects and seek to prejudice me some other wayes of whom I profess that I would make no more account than I have done of those who heretofore have contradicted me at whom I alwaies laugh as being assured of the issue that the business is to have but that I see that those new Calumnies and Persecutions do not determine in our greater or lesser Learning in which I will scarce pretend to any thing but extend so far as to attempt to asperse me with Crimes which ought to be and are more abhorred by me than Death it self Nor ought I to content my self that they are known to be unjust by those onely who know me and them but by all men whatsoever They persisting therefore in their first Resolution Of ruining me and whatsoever is mine by all imaginable waies and knowing how that I in my Studies of Astronomy and Philosophy hold as to the World 's Systeme That the Sun without changing place is situate in the Centre of the Conversion of the Celestial Orbes and that the Earth convertible about its own Axis moveth it self about the Sun And moreover understanding that I proceed to maintain this Position not onely by refuting the Reasons of Ptolomy and Aristotle but by producing many on the contrary and in particular some Physical pertaining to Natural Effects the causes of which perhaps can be by no other way assigned and others Astronomical depending upon many circumstances and encounters of new Discoveries in Heaven which manifestly confute the Ptolomaick Systeme and admirably agree with and confirm this other Hypothesis and possibly being ashamed to see the known truth of other Positions by me asserted different from those that have been commonly received and therefore distrusting their defence so long as they should continue in the Field of Philosophy for thâ—se respects I say they have resolved to try whether they could make a Shield for the fallacies of their Arguments of the Mantle of a feigned Religion and of the Authority of the Sacred Scriptures applyed by them with little judgment to the confutation of such Reasons of mine as they had neither understood nor so much as heard And first they have indeavoured as much as in them lay to divulge an opiniou thorow the Universe that those Propositions are contrary to the Holy Letters and consequently Damnable and Heretical And thereupon perceiving that for the most part the inclination of Mans Nature is more prone to imbrace those enterprizes whereby his Neighbour may
in the lower parts namely below the breach there is begot in the Channel of the River a certain ridge or shelf that is the bottom of the River is raised as is sufficiently manifest by experience and thus just in the same manner cutting the Bank at Bondeno there is at it were a breach made from which followeth the rising in the lower parts of the main Po being past the mouth of Pamaro which thing how pernitious it is let any one judge that understandeth these matters And therefore both for the small benefit and so many harms that ensue from maintaining this diversion I should think it were more sound advice to keep that Bank alwaies whole at Bondeno or in any other convenient place and not to permit that the Water of the Grand Po should ever come near to Ferara COROLLARIE XIV IN the Grand Rivers which fall into the Sea as here in Italy Po Adige And Arno which are armed with Banks against their excrescencies it s observed that far from the Sea they need Banks of a notable height which height goeth afterwards by degrees diminishing the more it approacheth to the Sea-coasts in such sort that the Po distant from the Sea about fifty or sixty miles at Ferara shall have Banks that be above twenty feet higher than the ordinary Water-marks but ten or twelve miles from the Sea the Banks are not twelve feet higher than the said ordinary Water-marks though the breadth of the River be the same so that the excrescence of the same Innundation happens to be far greater in measure remote from the Sea then near and yet it should seem that the same quantity of Water passing by every place the River should need to have the same altitude of Banks in all places But we by our Principles and fundamentals may be able to render the reason of that effect and say That that excesse of quantity of Water above the ordinary Water goeth alwaies acquiring greater velocity the nearer it approacheth the Sea and therefore decreaseth in measure and consequently in height And this perhaps might have been the cause in great part why the Tyber in the Innundation Anno 1578. issued not forth of its Channel below Rome towards the Sea COROLLARIE XV. FRom the same Doctrine may be rendred a most manifest reason why the falling Waters go lessening in their descent so that the same falling Water measured at the beginning of its fall is greater and bigger and afterwards by degrees lesseneth in measure the more it is remote from the beginning of the fall Which dependeth on no other than on the acquisition which it successively makes of greater velocity it being a most familiar conclusion among Philosophers that grave bodies falling the more they remove from the beginning of their motion the more they acquire of swiftnesse and therefore the Water as a grave body falling gradually velocitates and therefore decreaseth in measure and lesseneth COROLLARIE XVI ANd on the contrary the spirtings of a Fountain of Water which spring on high work a contrary effect namely in the beginning they are small and afterwards become greater and bigge and the reason is most manifest because in the beginning they are very swift and afterwards gradually relent their impetuosity and motion so that in the beginning of the excursion that they make they ought to be small and afterwards to grow bigger as in the effect is seen APPENDIX I. INto the errour of not considering how much the different velocities of the same running water in several places of its current are able to change the measure of the same water and to make it greater or lesse I think if I be not deceived that Ginlio Frontino a noble antient Writer may have faln in the Second Book which he writ of the Aqueducts of the City of Rome Whilst finding the measure of the Water Commentariis lesse than it was in erogatione 1263. Quinaries he thought that so much difference might proceed from the negligence of the Measures and when afterwards with his own industry he measured the same water at the beginning of the Aqueducts finding it neer 10000. Quinaries bigger than it was in Commentariis he judged that the overplus was imbeziled by Ministers and Partakers which in part might be so for it is but too true that the publique is almost alwayes defrauded yet neverthelesse I verily believe withal that besides the frauds of these Officers the velocities of the water in the place wherein Frontino measured it might be different from those velocities which are found in other places before measured by others and therefore the measures of the waters might yea ought necessarily to be different it having been by us demonstrated that the measures of the same running water have reciprocal proportion to their velocities Which Frontino not well considering and finding the water in Commentariis 12755. Quinaries in erogatione 14018 and in his own measure ad capita ductuum at the head of the fountain 22755. Quinaries or thereabouts he thought that in all these places there past different quantities of water namely greater at the fountain head then that which was in Erogatione and this he judged greater than that which was in Commentariis APPENDIX II. A Like mistake chanced lately in the Aqueduct of Acqua-Paola which Water should be 2000 Inches and so many effectively ought to be allowed and it hath been given in so to be by the Signors of Bracciano to the Apostolick-Chamber and there was a measure thereof made at the beginning of the Aqueduct which measure proved afterwards much lesse and short considered and taken in Rome and thence followed discontents and great disorders and all because this property of Running-Waters of increasing in measure where the velocity decreased and of diminishing in measure where the velocity augmented was not lookt into APPENDIX III. A Like errour in my judgement hath been committed by all those learned men which to prevent the diversion of the Reno of Bologna into Po by the Channels through which it at present runneth judged that the Reno being in its greater excrescence about 2000. feet and the Po being near 1000. feet broad they judged I say that letting the Reno into Po it would have raised the Water of Po two feet from which rise they concluded afterwards most exorbitant disorders either of extraordinary Inundations or else of immense and intolerable expences to the people in raising the Banks of Po and Reno and with such like weaknesses often vainly disturbed the minds of the persons concerned But now from the things demonstrared it is manifest That the measure of the Reno in Reno would be different from the measure of Reno in Po in case that the velocity of the Reno in Po should differ from the velocity of Reno in Reno as is more exactly determined in the fourth Proposition APPENDIX IV. NO less likewise are those Ingeneers and Artists deceived that have affirmed That letting the Reno into Po there would be
by the addition of new Water to that which it dischargeth after the encrease is made Proposition IV. Theor. II. 54 Proportion of a River when highâ—â— to it self when low Coroll I. 55 Q Quantity of Running Waters is never certain if with the Vulgar way of Measuring them their Velocities be not considered 32 Quantities of Waters which are discharged by a River answer in equality to the Velocities and times in which they are discharged Axiome I II III. 38 Quick-Height of a River what it is Definition V. 48 R Reason of the Proverb Take heed of the still Waters Coroll VI. 7 Reasons of Monsignore Corsini against the diversion of Reno into the Po of Volano 105 Reasons of Cardinal Capponi and Monsig Corsini for the turning of Reno into Main Po. 106 Two objections on the contrary and answers to them 104 105 What ought to be the proportion of the Heights of Reno in Reno and of Reno in Po. 110 Regulator what it is Definition IV. 48 Relation of the Waters of Bologna and Ferrara by Monsignore Corsini 100 Reno in the Valleys and its bad effects 100 101 Two wayes to divert it 103 The facility and utility of those wayes Ibid. The difficulties objected 104 Reply to Bartolotti touching the dangers of turning Eiume Morto into Serchio 83 Retardment of the course of a River caused by its Banks Appendix VII 19 Risings made by Flood-Gates but small Appendix XIII 26 Rivers that are shallow swell much upon small showers such as are deep rise but little upon great Floods Corollary III. 6 Rivers the higher they are the swifter Ibid. Rivers the higher they are the lesse they encrease upon Floods 49 Rivers when they are to have equal and when like Velocity Ibid. Rivers in falling into the Sea form a Shelf of Sand called Cavallo 65 Five Rivers to be diverted from the Lake of Venice and the inconveniences that would ensue thereupon 74 75 A River of Quick-height and Velocity in its Regulator being given if the Height be redoubled by new Water it redoubleth also in Velocity Proposition II. Theorem I. 51 Keepeth the proportion of the heights to the Velocities Corollary 52 S Sand and Mud that entereth into the Lake of Venice and the way to examine it 76 Seas agitated and driven by the Winds stop up the Ports 64 65 Sections of a River what they are Definition I. 37 Sections equally swift what they are Definition II. Ibid. Sections of a River being given to conceive others equal to them of different breadth height and Velocity Petition 38 Sections of the same River and their Proportions to their Velocities Coroll I. 42 Sections of a River discharge in any whatsoever place of the said River equal quantities of Water in equal times Proposition I. 39 Sile River what mischiefes it threatneth diverted from the Lake 74 Spirtings of Waters grow bigger the higher they go Coroll XVI 16 Streams of Rivers how they encrease and vary Coroll I. 6 Streams retarded and the effects thereof Coroll IX 8 T Table of the Heights Additions and Quantities of Waters and its use 56 Thrasimenus Vide Lake Time how it s measured in these Operations of the Waters 49 Torrents encrease at the encreasing of a River though they carry no more Water than before Coroll IV. 6 Torrents when they depose and carry away the Sand. Coroll V. 7 Torrents and their effects in a River 6 7 Torrents that fall into the Valleys or into Po of Valano and their mischiefs prevented by the diverting of Reno into Main Po. 100 Tyber and the causes of its inundations Coroll VIII 8 V Valleys of Bologna and Ferrara their inundations and disorders whence they proceed 97 Velocity of the Water shewn by several Examples 3 Its proportion to the Measure 5 Velocities equal what they are 47 Velocities like what they are 47 48 Velocities of Water known how they help us in finding the Lengths 113 A Fable to explain the truth thereof Ibid. Venice Vide Lake Vse of the Regulator in measuring great Rivers Consideration I. 60 W Waters falling why they disgross Coroll XVI 16 Waters how the Length of them is Measured 70 Waters that are imployed to flow Grounds how they are to be distributed 19 53 54 Waters to be carryed in Pipes to serve Aquaducts and Conduits how they are to be Measured 15 116 Way to know the rising of Lakes by Raines 28 Way of the Vulgar to Measure the VVaters of Rivers 68 Wind Gun and Portable Fountain of Vincenzo Vincenti of Urbin 11 Windes contrary retard and make Rivers encrease Coroll VII 8 The END of the TABLE of the Second Part of the First TOME Copernicus reputeth the Earth a Globe like to a Planet Coelestial substances that are in alterable and Elementary that be alterable art necessary in the opinion of Aristotle Aristotle maketh the World perfect because it hath the threefold demension Aristotles demonstrations to prove the dimensions to be three and no more The number three celebrated amongst the Pythagorians Omne Totum Perfectum Or Solid Plato held that humane understanding partook of divinity because it understood numbers The Mystery of Pythagorick numbers fabulous De Papyrio pâ—aetextato Gellius 1. 2. 3. A Geometrical demonstration of the triple dimension In physical proofs â—eâ—metrical exactness is not necessary Parts of the world are two according to Aristotle Coelestial and Elementary contrary to one another Local motion of three kinds right circular mixt Circular and streight motions are simple as proceeding by simple lines Ad medium à 〈◊〉 circa medium The definition of Nature either imperfect or unseasonable produced by Aristotle The Helix about the Cylinder may be said to be a simple line Aristotle accommodates the rules of Architecture to the frame of the World and not the frame to the rules Right motion sometimes simple and sometimes mixt according to Arist. The circular line perfect according to Aristotle and but the right imperfect and why The world is supposed by the Author to be perfectly ordinate Streight motion impossible in the world exactly ordinate Right motion nature infinite Motion by a right line naturally impossible Nature attempts not things impossible to be effected Right motion might perhaps be in thâ— first Chaos Right motion is commodious to range in order things out of order Mundane bodies moved in the beginning in a right line and afterwards circularly according to Plato * Thus doth he coverâ—ly and modestly stile himselfe throughout this work A moveable being in a state of rest shall not move unless it have an inclination to some particular place The moveable accelerates its motion going towards the place whither it hath an inclination The moveable passing from rest goeth thorow all the degrees of tardity Rest the infinite degree of tardity The moveable doth not accelerate save only as it approacheth nearer to us term Nature to introduce in the moveable a certain degree of velocity made it move in a right line Vniform
part of the Air If therefore he held it not impossible to mix the right motion upwards with the circular communicated to the Fire and Air from the concave of the Moon much less ought he to account impossible the mixture of the right motion downwards of the stone with the circular which we presuppose natural to the whole Terrestrial Globe of which the stone is a part SIMPL. I see no such thing for if the element of Fire revolve round together with the Air it is a very easie yea a necessary thing that a spark of fire which from the Earth mounts upwards in passing thorow the moving air should receive the same motion being a body so thin light and easie to be moved but that a very heavy stone or a Canon bullet that descendeth from on high and that is at liberty to move whither it will should suffer it self to be transported either by the air or any other thing is altogether incredible Besides that we have the Experiment which is so proper to our purpose of the stone let fall from the round top of the Mast of a ship which when the ship lyeth still falleth at the Partners of the Mast but when the ship saileth falls so far distant from that place by how far the ship in the time of the stones falling had run forward which will not be a few fathoms when the ships course is swift SALV There is a great disparity between the case of the Ship and that of the Earth if the Terrestrial Globe be supposed to have a diurnal motion For it is a thing very manifest that the motion of the Ship as it is not natural to it so the motion of all those things that are in it is accidental whence it is no wonder that the stone which was retained in the round top being left at liberty descendeth downwards without any obligation to follow the motion of the Ship But the diurnal conversion is ascribed to the Terrestrial Globe for its proper and natural motion and consequently it is so to all the parts of the said Globe and as being impress'd by nature is indelible in them and therefore that stone that is on the top of the Tower hath an intrinsick inclination of revolving about the Centre of its Whole in twenty four hours and this same natrual instinct it exerciseth eternally be it placed in any state whatsoever And to be assured of the truth of this you have no more to do but to alter an antiquated impression made in your mind and to say Like as in that I hitherto holding it to be the property of the Terrestrial Globe to rest immoveable about its Centre did never doubt or question but that all whatsoever particles thereof do also naturally remain in the same state of rest So it is reason in case the Terrestrial Globe did move round by natural instinct in twenty four hours that the intrinsick and natural inclination of all its parts should also be not to stand still but to follow the same revolution And thus without running into any inconvenience one may conclude that in regard the motion conferred by the force of Oars on the Ship and by it on all the things that are contained within her is not natural but forreign it is very reasonable that that stone it being separated from the ship do reduce its self to its natural disposure and return to exercise its pure simple instinct given it by nature To this I add that it 's necessary that at least that part of the Air which is beneath the greater heights of mountains should be transported and carried round by the roughness of the Earths surface or that as being mixt with many Vapours and terrene Exhalations it do naturally follow the diurnal motion which occurreth not in the Air about the ship rowed by Oars So that your arguing from the ship to the Tower hath not the force of an illation because that stone which falls from the round top of the Mast entereth into a medium which is unconcern'd in the motion of the ship but that which departeth from the top of the Tower finds a medium that hath a motion in common with the whole Terrestrial Globe so that without being hindred rather being assisted by the motion of the air it may follow the universal course of the Earth SIMPL. I cannot conceive that the air can imprint in a very great stone or in a gross Globe of Wood or Ball of Lead as suppose of two hundred weight the motion wherewith its self is moved and which it doth perhaps communicate to feathers snow and other very light things nay I see that a weight of that nature being exposed to any the most impetuous wind is not thereby removed an inch from its place now consider with your self whether the air will carry it along therewith SALV There is great difference between your experiment and our case You introduce the wind blowing against that stone supposed in a state of rest and we expose to the air which already moveth the stone which doth also move with the same velocity so that the air is not to conferr a new motion upon it but onely to maintain or to speak better not to hinder the motion already acquired you would drive the stone with a strange and preternatural motion and we desire to conserve it in its natural If you would produce a more pertinent experiment you should say that it is observed if not with the eye of the forehead yet with that of the mind what would evene if an eagle that is carried by the course of the wind should let a stone fall from its talons which in regard that at its being let go it went along with the wind and after it was let fall it entered into a medium that moved with equal velocity I am very confident that it would not be seen to descend in its fall perpendicularly but that following the course of the wind and adding thereto that of its particular gravity it would move with a transverse motion SIMPL. But it would first be known how such an experiment may be made and then one might judg according to the event In the mean time the effect of the ship doth hitherto incline to favour our opinion SALV Well said you hitherto for perhaps it may anon change countenance And that I may no longer hold you in suspense tell me Simplicius do you really believe that the Experiment of the ship squares so very well with our purpose as that it ought to be believed that that which we see happen in it ought also to evene in the Terrestrial Globe SIMPL. As yet I am of that opinion and though you have alledged some small disparities I do not think them of so great moment as that they should make me change my judgment SALV I rather desire that you would continue therein and hold for certain that the effect of the Earth would exactly answer that of
the ship provided that when it shall appear prejudicial to your cause you would not be humorous and alter your thoughts You may haply say Forasmuch as when the ship stands still the stone falls at the foot of the Mast and when she is under sail it lights far from thence that therefore by conversion from the stones falling at the foot is argued the ships standing still and from its falling far from thence is argued her moving and because that which occurreth to the ship ought likewise to befall the Earth that therefore from the falling of the stone at the foot of the Tower is necessarily inferred the immobility of the Terrestrial Globe Is not this your argumentation SIMPL. It is and reduced into that conciseness as that it is become most easie to be apprehended SALV Now tell me if the stone let fall from the Round-top when the ship is in a swift course should fall exactly in the same place of the ship in which it falleth when the ship is at anchor what service would these experiments do you in order to the ascertaining whether the vessel doth stand still or move SIMPL. Just none Like as for exemple from the beating of the pulse one cannot know whether a person be asleep or awake seeing that the pulse beateth after the same manner in sleeping as in waking SALV Very well Have you ever tryed the experiment of the Ship SIMPL. I have not but yet I believe that those Authors which alledg the same have accurately observed it besides that the cause of the disparity is so manifestly known that it admits of no question SALV That it is possible that those Authors instance in it without having made tryal of it you your self are a good testimony that without having examined it alledg it as certain and in a credulous way remit it to their authority as it is now not onely possible but very probable that they likewise did I mean did remit the same to their Predecessors without ever arriving at one that had made the experiment for whoever shall examine the same shall find the event succeed quite contrary to what hath been written of it that is he shall see the stone fall at all times in the same place of the Ship whether it stand still or move with any whatsoever velocity So that the same holding true in the Earth as in the Ship one cannot from the stones falling perpendicularly at the foot of the Tower conclude any thing touching the motion or rest of the Earth SIMPL. If you should refer me to any other means than to experience I verily believe our Disputations would not come to an end in haste for this seemeth to me a thing so remote from all humane reason as that it leaveth not the least place for credulity or probability SALV And yet it hath left place in me for both SIMPL. How is this You have not made an hundred no nor one proof thereof and do you so confidently affirm it for true I for my part will return to my incredulity and to the confidence I had that the Experiment hath been tried by the principal Authors who made use thereof and that the event succeeded as they affirm SALV I am assured that the effect will ensue as I tell you for so it is necessary that it should and I farther add that you know your self that it cannot fall out otherwise however you feign or seem to feign that you know it not Yet I am so good at taming of wits that I will make you confess the same whether you will or no. But Sagredus stands very mute and yet if I mistake not I saw him make an offer to speak somewhat SAGR. I had an intent to say something but to tell you true I know not what it was for the curiosity that you have moved in me by promising that you would force Simplicius to discover the knowledg which he would conceal from us hath made me to depose all other thoughts therefore I pray you to make good your vaunt SALV Provided that Simplicius do consent to reply to what I shall ask him I will not fail to do it SIMPL. I will answer what I know assured that I shall not be much put to it for that of those things which I hold to be false I think nothing can be known in regard that Science respecteth truths and not falshoods SALV I desire not that you should say or reply that you know any thing save that which you most assuredly know Therefore tell me If you had here a flat superficies as polite as a Looking-glass and of a substance as hard as steel and that it were not paralel to the Horizon but somewhat inclining and that upon it you did put a Ball perfectly spherical and of a substance grave and hard as suppose of brass what think you it would do being let go do not you believe as for my part I do that it would lie still SIMPL. If that superficies were inclining SALV Yes for so I have already supposed SIMPL. I cannot conceive how it should lie still nay I am confident that it would move towards the declivity with much propensness SALV Take good heed what you say Simplicius for I am confident that it would lie still in what ever place you should lay it SIMPL. So long as you make use of such suppositions Salvictus I shall cease to wonder if you inferr most absurd conclusions SALV Are you assured then that it would freely move towards the declivity SIMPL. Who doubts it SALV And this you verily believe not because I told you so for I endeavoured to perswade you to think the contrary but of your self and upon your natural judgment SIMPL. Now I see what you would be at you spoke not this as really believing the same but to try me and to wrest matter out of my own mouth wherewith to condemn me SALV You are in the right And how long would that Ball move and with what velocity But take notice that I instanced in a Ball exactly round and a plain exquisitely polished that all external and accidental impediments might be taken away And so would I have you remove all obstructions caused by the Airs resistance to division and all other casual obstacles if any other there can be SIMPL. I very well understand your meaning and as to your demand I answer that the Ball would continue to move in infinitum if the inclination of the plain should so long last and continually with an accelerating motion for such is the nature of ponderous moveables that vires acquirant eundo and the greater the declivity was the greater the velocity would be SALV But if one should require that that Ball should move upwards on that same superficies do you believe that it would so do SIMPL. Not spontaneously but being drawn or violently thrown it may SALV And in case it were thrust forward by the impression of some violent impetus from