refraction 6. An answer to the arguments brought in favour of Monsieur des Cartes his opinion 7. The true cause of refraction of light both at its entrance and at its going out from the refleing body 8. A general rule to know the nature of reflection and refractions in all sorts of surface 9. A body of greater parts and greater pores makes a greater refraction than one of lesser parts and lesser pores 10. A confirmation of the former doctrine out of the nature of bodies that refract light CHAP. XIV Of the composition qualities Generation of mixed Bodies 1. The connexion of this chapter with the rest and the Authours intent in it 2. That there is a least sise of bodies and that this least sise is found in fire 3. The first conjunction of parts is in bodies of least sise and it is made by the force of Quantity 4. The second sort of conjunction is compactedness in simple Elements and it proceeds from density 5. The third conjunction is of parts of different Elements and it proceeds from quantity and density together 6. The reason why liquid bodies do easily joyn together and dry ones difficultly 7. That no two hard bodies can touch one another immediately 8. How mixed bodies are framed in general 9. The cause of the several degrees of solidity in mixed bodies 10. The Rule whereto are reduced all the several combinations of Elements in compounding of mixed bodies 11. Earth and water are the basis of all permanent mixed bodies 12. What kind of bodies those are where water is the basis and earth the predominant Element over the other two 13. Of those bodies where water being the basis air is the predominant Element 14. What kind of bodies result where water is the basis and fire the predominant Element 15. Of those bodies where water is in excess it alone being both the basis and the predominant Element 16. Of those bodies where earth alone is the basis and also the predominant in excess over the other three Elements 17. Of those bodies where earth is the basis water is the predominant element over the other two 18. Of those bodies where earth being the basis air is the predominant 19. Of those bodies where earth being the basis fire is the predominant 20. All the second qualities of mixed bodies arise from several combinations of the first qualities and are at last resolv'd into several degrees of rarity density 21. That in the Planets Stars there is a like variety of mixed bodies caused by light as here on earth 22. In what manner the Elements work on one another in the composition of mixed bodies and in particular fire which is the most active 23. A particular declaration touching the generation of Metals CHAP. XV. Of the Dissolution of Mixed Bodies 1. Why some bodies are brittle and others tough or apt to withstand outward violence the first instrument to dissolve mixed bodies 2. How outward violence doth work on the most compacted bodies 3. The several effects of fire the second and chiefest instrument to dissolve all compounded bodies 4. The reason why some bodies are not dissolved by fire 5. The reason why fire melteth gold but cannot consume it 6. Why Lead is easily consumed and calcinted by fire 7. Why and how some bodies are divided by fire into Spirits Waters Oyls Salts and Earth And what those parts are 8. How water the third instrument to dissolve bodies dissolvs calx into salt and so into terra damnata 9. How water mingled with salt becomes a most powerful Agent to dissolve other bodies 10. How putrefaction is caused CHAP. XVI An Explication of certain Maxims touching the operations and qualies of bodies and whether the Elements be found pure in any part of the world 1. What is the Sphere of activity in corporeal agents 2. The reason why no body can work in distance 3. An objection answer'd against the manner of explicating the former axiome 4. Of re-action and first in pure local motion that each Agent must suffer in acting and act in suffering 5. The former Doctrine applyed to other local motions design'd by particular names And that Suisseths argument is of no force against this way of doctrine 6. Why some notions do admit of intension and remission and others not 7. That in every part of our habitable world all the four elements are found pure in small atoms but not in any great bulk CHAP. XVII Of Rarefaction and Condensation the two first motions of Particular bodies 1. The Authours intent in this and the following chapters 2. That bodies may be rarified both by outward and inward heart and how this is perform'd 3. Of the great effects of Rarefaction 4. The first manner of condensation by heat 5. The second manner of condensation by cold 6. That Ice is not water rarified but condensed 7. How Wind Snow and Hail are made and wind by rain allaid 8. How parts of the same or divers bodies are joyn'd more strongly together by condensation 9. Vacuities cannot be the reason why water impregnated to the full with one kind of salt will notwithstanding receive more of another 10. The true reason of the former effect 11. The reason why bodies of the same nature do joyn more easily together than others CHAP. XVIII Of another motion belonging to Particular bodies called Attraction and of certain operations term'd Magical 1. What Attraction is and from whence it proceeds 2. The true sense of the Maxime that Nature abhors from vacuitys 3. The true reason of attraction 4. Water may be brought by the force of attraction to what height soever 5. The doctrine touching the attraction of water in Syphons 6. That the Syphon doth not prove water to weigh in its own orb 7. Concerning attraction caus'd by fire 8. Concerning attraction made by virture of hot bodies amulets c 9. The natural reason given for divers operations esteem'd by some to be magical CHAP. XIX Of three other motions belonging to particular bodies Filtration Restitution and Electrical attraction 1. What is Filtration and how it is effected 2. What causes the water in Filtration to ascend 3. Why the filter will not drop unless the label hang lower than the water 4. Of the motion of Restitution and why some bodies stand bent others not 5. Why some bodies return only in part to their natural figure others entirely 6. Concerning the nature of those bodies which shrink aand stretch 7. How great and wonderful effects proceed from small plain and simple principles 8. Concerning Electrical attratâ—on and the causes of it 9. Cabeus his opinion refuted concerning the cause of Electrical motions CHAP. XX. Of the Loadstones generation and its particulas motions 1. The extreme heat of the Sun under the Zodiack draws a stream of air from each Pole into the torrid Zone 2. The atomes of these two streams coming together are apt to incorporate with one another 3. By the meeting and mingling together
Of the great effects of Rarefaction 4. The first manner of condensation by heat 5. The second manner of condensation by cold 3. That Ice is not water rarifiâ—d but condensed 7. How wind snow and hail are made and wind by rain allayed 8. How parts of the same or divers bodies are joyned more strongly together by condensation 9. Vacuities cannot be the reason why water impregnated to the full with one kind of salt will notwithstanding receive more of another 10. The true reason of the former effect 11. The reason why bodies of the same nature jâ—yn more easily together then others 1. What attraction is and from whence it proceeds 1. The true sense of the Maxime that Nature abhors from vacuity 3. The true rea son of attraction 4. Water may be brought by the force of attraction to what height soever 5. The doctrine touching the attraction of water in Syphons 6. That the Syphon doth not prove water to weigh in its own orb 7. Concerning attraction caused by fire 8. Concerning attraction made by virtue of hot bodies amulets c. 9. The natural reason given for divers operations esteemed by some to be magical 1. What is Filtration and how it is effected 2. What causes the water in filtration to ascend 3. Why the filter will not drop unless the label hang lower then the water 4. Of the motion of Râ—stitution and why some bodies stand bent others not 5. Why some bo dies return only in part to their natural figure others entirely 6. Concerning the nature of those bodies which shrink and stretch 7. How great wonderful effects proceed from smal plain and simple principles 8. Concerning Electrical at action and the causes of it 6. Cabeus his opinion reâ—uted concerning the cause of Electrical motions 1. The extreme heat of the Sun under the Zodiack draws a stream of air from each pole into the Torrid Zone * Chap. 18. Sect. 7. 2. The Atoms of these two streams coming together are apt to incorporate with one another 3. By the meeting and mingling together of these streams at the Equator divers rivolets of Atoms of each Pole are continuated from one Pole to the other 4. Of these Atoms incorporated with some fit matter in the bowels of the earth is made a stone 5. This stone works by emanations joyned with agreeing streams that meet them in the air and in fine it is a Loadstone 6 A methode for making experiences on any subject 7. The Loadstones generation by atoms flowing from both Poles is confirmd by experiments observ'd in the stone it self 8. Experiments to prove that the Loadstone works by emanations meeting with agreeing streames 1. The operations of the loadstone are wrought by bodies and not by qualities 2. Objections against the former position answer'd 3. The Loadstone is imbued with his virtue from another body 4 The virtue of the Loadstone is a double and not one simple virtue 5. The virtue of the Loadstone works more strongly in the poles of it then in any other part 6. The loadstone sends forth its emanations spherically Which are of two kindâ— and each kind is strongest in that Hemisphere through whose polary parts they issue out 7. Putting two loadstones within the sphere of one another every part of one loadstone doth not agree wâ—th every part of the other loadstone 8. Concetning the declination and other respects of a needle towards the loadstone it touches 8. The virtue of the Loadstone goes from end to end in lines almost parallel to the Axis 10. The virtue of the Loadstone is not perfectly spherical though the stone be such 11. The intention of nature in all the operations of the loadstone is to make an union betwixt the attractive and attracted bodies 12. The main globe of the earth is not a Loadstone 13. The loadstone is generated in all parts or Climâ—t's of the earth 14. The conformity betwixt the two motions of magnetick things and of heavy things 1. Which is the North and which the South Pole of a Loadstone 2. Whether any bodies besides magnetick ones be attractive 3. Whether an iron placed perpendicularly towards the earth gets a magnetical virtue of pointing towards the north or towards the south in that end that lies downwards 4. Why loadstones affect iron better than one another 5. Gilberts reason refuted touching a cap'd Loadstone that takes up more iron then one not cap'd and an iron impregnated that in some case draws more strongly then the stone it self Galileus his opinion touching the former effects refuted 7. The Authors solution to the former questions 8. The reason why in the former case a lesser Loadstones draws the interjacent iron from the greater 9. Why the variation of a touched needle from the North is greater the nearer you go to the Pole 10. Whether in the same part of the world a touched needle may it one time vary more fâ—om the North and at another time less 11. The whâ—le doctrine of the loâ—dstone sum'd up in short 1. The connexion of the following Chapters with the precedent ones 2. Concerning several compositions of mixed bodies 3. Two sorts of Living Creatures 4. An engine to express the first sort of living creatures 5. Another Engine by which may be expressed the second sort of living creatures 4. The two former engines and some other comparisons applied to express the two several sorts of living creatures 7. How plants are framed 8. How Sensitive Creatures are formed 1. The opinion that the seed contains formally every part of the parent 2. The former opinion rejected 3. The Authours opinion of this question 4. Their opinion refuted who hold that every thing contains formally all things 5. The Authors opinion concerning the generation of Animals declared and confirm'd That one substance is changed into another 7. Concerning the hatching of Chickens and the generation of the other Animals 8. From whence it happens that the deficiences or excresences of the parents body are often seen in their children 9. The difference between the Authors opinion anâ—â—he former 〈◊〉 10 That the heart is imbued with the general specifike vertues of the whole body wherby is confirm'd the doctrine of the two former Paragraphes 11 That the heart is the first part generated in a living creatures 1. That the figure of an Animal is produced by ordinary second causes as well as any other corporeal effect 2. That the several figures of bodies proceed from a defect in one of three dimensions caused by the circumference of accidental causes 3. The former doctrine is confirmd by several instances 4. The same doctrine applyed to plants 4. The same doctrine declared in leaves of trees 16. The same applied to the bodies of Animals 7. In what sense the Author admits of vis formatrix 1. From whence proceeds the primary motion growth in Plants 2. Mr. des Cartes his opinion touching the motion of the heart 3. The former opinion rejected 4. The Authors opinion
could strike it But it is evident say you out of these pretended causes of this motion that such atomes cannot move so swiftly downwards as a great dense body since their littleness and their rarity are both of them hindering to their motion Therefore this cannot be cause of that effect which we call gravity To this I reply That to have the atoms give these blows to a descending dense body 't is not requir'd that their natural and ordinary motion should be swifter then the descent of such a dense body but the very descent of it occasions their striking it for as it falls and makes it self a way through them they divide themselves before it and swell on the sides and a little above it and presently close again behind it and over it assoon as it is past Now that closing to hinder vacuity of space is a sudden one and thereby attains great velocity which would carry the atoms in that degree of velocity further than the descending body if they did not encounter with it in their way to retard them which encounter and tarding implyes such strokes upon the dense body as we suppose to cause this motion And the like we see in water into which letting a stone fall presently the water that was divided by the stone and swells on the sides higher then it was before closes upon the back of the descending stone and follows it so violently that for a while after it leaves a purling hole in the place where the stone went down till by the repose of the stone the water returns likewise to its quiet and so its superficies becomes even In the third place an enquiry occurs emergent out of this doctrine of the cause of bodies moving upwards and downwards Which is Whether there would be any natural motion deep in the earth beyond the activity of the Sun beams for out of these principles it follows that there would not and consequently there must be a vast Orb in which there would be no motion of gravity or levity For suppose the Sun beams might pierce a thousand miles deep into the body of the earth yet there would still remain a mass whose Diameter would be near 5000 miles in which there would be no gravitation nor the contrary motion For my part I shall make no difficulty to grant the inference as far as concerns motion caused by our Sun for what inconvenience would follow out of it But I will not offer at determining whether there may not be enclosed within that great sphere of earth some other fire such as the Chymists talk of an Archeus a Demogorgon seated in the centre like the heart in animals which may raise up vapours and boyl an air out of them and divide gross bodies into atoms and accordingly give them motions answerable to ours but in different lines from ours according as that fire or Sun is situated Since the far-searching Authour of the Dialogues de Mundo hath left that speculation undecided after he had touched upon it in the Twelfth knot of his first Dialogue Fourthly it may be objected that if such descending atoms as we have described were the cause of a bodies gravity and descending towards the center the same body would at divers times descend more and less swiftly for example after midnight when the atoms begin to descend more slowly the same body would descend more slowly in a like proportion and not weigh so much as it did in the heat of the day The same may be said of Summer and Winter for in Winter time the atoms seem to be more gross and consequently to strike more strongly upon the bodies they meet with in their way as they descend yet on the other side they seem in the Summer to be more numerous as also to descend from a greater height both which circumstances will be cause of a stronger stroke and more vigorous impulse on the body they hit And the like may be objected of divers parts of the World for in the Torrid Zone it will always happen as in Summer in places of the Temperate Zone and in the Polar times as in deepest winter so that no where there should be any standard or certainty in the weight of bodies if it depended upon so mutable a cause And it makes to the same effect that a body which lies under a thick rock or any other very dense body that cannot be penetrated by any great store of atoms should not be so heavy as it would be in the open and free air where the atoms in their compleat numbers have their full strokes For answer to these and such like instances we are to note first that 't is not so much the number or violence of the percussion of the striking atoms as the density of the thing strucken which gives the measure to the descending of a weighty body and the chief thing which the stroak of the atoms gives to a dense body is a determination of the way which a dense body is to cut to it self therfore multiplication or lessening of the atoms will not make any sensible difference betwixt the weight of one dense body where manya toms strike and an other body of the same density where but a few strike so that the stroak downwards of the descending atoms be greater then the stroke upwards of the ascending atoms and therby determines it to weigh to the Centrewards and not rise floating upwards which is all the sensible effect we can perceive Next we may observe that the first particulars of the objection do not reach home to enfeeble our doctrine in this particular although we admit them to be in such sort as they are proposed for they withal imply such a perpetual variation of causes ever favourable to our position that nothing can be infer'd out of them to repugne against it As thus When there are many atoms descending in the air the same general cause which makes them be many makes them also be light in proportion to their multitude And so when they are few they are heavy likewise when the atoms are light the air is rarified and thin and when they are heavy the air is thick And so upon the whole matter 't is evident that we cannot make such a precise and exact judgement of the variety of circumstances as to be able to determine when there is absolutely more cause of weight and when less And as we find not weight enough in either side of these opposite circumstances to turn the scales in our discourse so likewise we find the same indifference in experience it self for the weights we use do weigh equally in mysty weather and in clear and yet in rigor of discourse we cannot doubt but that in truth they do not gravitate or weigh so much though the difference be imperceptible to sense when the air is thick and foggy as when its pure and rarified Which thickness of the Medium when it arrives to a very
the operation of the understanding is nothing else but the inward superficies of a body that compasses and immediately conteines another Which ordinarily being of a rare body that doth not shew it self to us namely the Air is for the most part unknown by us But because nothing can make impression on our minds and cause us to give it a name otherwise then by being known therfore our understanding to make a compleat notion must add something else to this fleeting and unremarkable Superficies that may bring it to our acquaintance And for this end we may consider further that as this Superficies hath in it self so the bodie enclosed in it gains a certain determinate respect to the stable and immoveable bodies that environ it As for example we understand such a Tree to be in such a place by having such and such respects to such a Hill near it or to such a House that stands by it or to such a River that runs under it or to such an immoveable point of the Heaven that from the Suns rising in the Equinox is called East and such like To which purpose it imports not whether these that we call immoveable bodies and points be truly so or do but seem so to mankind For man talking of things according to the notions he frames of them in his mind speech being nothing else but an expression to another man of the images he hath within himself and his notions being made according to the seeming of the things he must needs make the same notions whether the things be truly so in themselvs or but seem to be so when that seeming or appearance is always constantly the same Now then when one body dividing another gets a new immediate clothing and consequently new respects to the stable and immoveable bodies or seeming such that environ it we vary in our selves the notion we first had of that thing conceiving it now accompanied with other circumstances and other respects then formerly it had Which notion we express by saying it has changed its place and is now no longer where it was at the first And this change of place we call Locall motion to wit the departing of a body from that hollow superficies which inclosed it and its changing to another wherby it gains new respects to those parts of the World that have or in some sort may seem to have immobility and fixed stableness So as hence 't is evident that the substance of Locall motion consists in Division and that the alteration of Locality follows Division in such sort as the becoming like or unlike of one wall to another follows the action whereby one of them becomes white And therefore in Nature we are to seek for any entity or special cause of applying the moved body to a place as place which is but a respect consequent to the effect of division but only to consider what real and physical action unites it to that other body which is called its place and truly serves for that effect And consequently they who think they have discover'd a notable subtilty by bringing in an Entity to unite a Body to its Place have strain'd beyond their strength and grasped but a shadow Which will appear yet more evident if they but mark well how nothing is divisible but what of it self abstracting from division is one For the nature of Division is the making of many which implies that what is to be divided must of necessity be not-many before it be divided Now Quantity being the subject of division 't is evident that purely of it self and without any force or adjoyned helps it must needs be one wherever some outward agent doth not introduce multiplicity upon it And whenever other things work upon quantity as quantity it is not the nature and power of their operation to produce unity in it and make it one for it is already one but contrariwise the immediate necessary effect that flows from them in this case is to make one quantity many according to the circumstances that accompany the divider and that which is to be divided And therefore although we may seek causes why some one thing sticks faster together then some other yet to ask absolutely why a body sticks together were prejudicial to the nature of quantity whose essence is to have parts sticking together or rather to have such unity as without which all divisibility must be excluded Out of which discourse it follows that in local motion we are to look onely for a cause or power to divide but not for any to unite For the very nature of quantity unites any two parts that are indistant from one another without needing any other cement to glue them together as we see the parts of water and all liquid substances presently unite themselves to other parts of like bodies when they meet with them and to solid bodies if they chance to be next them And therefore 't is vain to trouble our heads with Unions and imaginary Moods to unite a body to the place it is in when their own nature makes them one as soon as they are immediate to each other And accordingly if when we see a Boul move we would examine the causes of that motion we must consider the quantity of air or water it makes to break from the parts next to it to give place to it self and not speculate upon an intrinsecall relation from the body to a certain part of the imaginary space they will have to run through all things And by ballancing that quantity of air or water which it divides we may arrive to make an estimate of what force the Boul needs to have for its motion Thus having declar'd that the locality of motion is but an extrinsecall denomination and no reality in the thing moved we may now cast an eye upon a vast consequence that may be deduced out of what we have hitherto said For if we consider the nature of a Body that is that a Body is a Body by quantity and that the formall notion of Quantity is nothing else but Divisibility and that the adequate Act of Divisibility is Division 't is evident there can be no other Operation upon Quantity nor by consequence among Bodies but must either be such Division as we have here explicated or what must necessarily follow out of such division And Division as we have even now explicated being Locall Motion 't is evident that All operations among Bodies are either Local Motion or such as follow out of Local motion Which conclusion however unexpected and at first hearing appearing a Paradox will nevertheless by the ensuing work receive such evidence as it it cannot be doubted of and that not only by force of argumentation and by necessity of notions as is already reduced but also by experience and declaratiosns of particulars as they shall occur But now to apply what we have said to our proposed subject 't is obvious to every
an aptitude the better to cut the medium and from the mltitude of little atomes descending that strike upon it and press it the way they go which is downwards then it would not import whether the inner part of that body were as solid as the outward parts for it cuts with only the outward and is smitten only upon the outward And yet experience shews us the contrary for a great bullet of lead that is solid and lead throughout descends faster then if three quarters of the Diameiter were hollow within and such a one falling upon any resisting substance works a greater effect then a hollow one And a ball of brass that hath but a thin outside of metal will swim upon the water when a massie one sinks presently Whereby it appears that it is rather some other quality belonging to the very bulk of the metal in it self and not these outward causes that occasion gravity But this difficulty is easily overcome if you consider how subtile those atomes are which descending downwards striking upon a body in their way cause its motion likewise downwards for you may remember how we have shew'd them to be the subtilest and the minutest divisions that Light the subtilest and sharpest divider in nature can make It is then easie to conceive that these extreme subtile bodies penetrate all others as light doth glass and run through them as sand through a small sieve or as water through a spunge so that they strike not only upon the Superficies but as well in every most interiour part of the whole body running quite through it all by the pores of it And then it must needs follow that the solider it is and the more parts it has within as well as without to be strucken upon the faster it go and the greater effect it must work in what falls upon whereas if three quarters of the Diameter of it within should be fill'd with nothing but air the atoms would fly without any considerable effect through all that space by reason of the rarity cessibility of it And that these atoms are thus subtile is manifest by several effects which we see in nature Divers Authors that write of Egypt assure us that though their houses be built of strong stone nevertheless a clod of earth laid in the inmost rooms and shut up from all appearing communication with air will encrease its weight so notably as therby they can judge the change of weather which will shortly ensue Which can proceed from no other cause but a multitde of little atoms of Saltpeter which floating in the air penetrate through the strongest wals and all the massie defences in their way and settle in the cold of earth as soon as they meet with it because it is of a temper fit to entertain and conserve embody them Delights have shewed us the way how to make the spirits or atoms of Snow and Saltpeter pass through a glass vessel which Alchimists hold to be the most impenetrable of all they can find to work with In our own bodies the aches which feeble parts feel before change of weather and the heaviness of our heads and shoulders if we remain in the open air presently after sunset abundantly testifie that even the grosser of these atoms which are the first that fall do vehemently penetrate our bodies so as sense will make us believe what reason peradventure could not But besides all this there is yet a more convincing reason why the descending atomes should move the whole density of a body even though it were so dense that they could not penetrate it and get into the bowels of it but must be content to strike barely upon the outside of it For nature has so order'd the matter that when dense parts stick close together and make the length composed of them to be very stiff one cannot be moved but that all the rest which are in that line must likewise be thereby moved so that if all the world were composed of atoms closse sticking together the least motion imaginable must drive on all that were in a straight line to the very end of the world This you see is evident in reason and experience confirms it when by a little knock given at the end of a long beam the shaking which makes sound reaches sensibly to the other end The blind man that governs his steps by feeling in defect of eyes receives advertisements of remote things through a staff which he holdeth in his hands peradventure more particularly then his eyes could have directed him And the like is of a deaf man that hears the sound of an Instrument by holding one end of a stick in his mouth whiles the other end rests upon the Instrument And some are of opinion and they not of the rank of vulgar Philosophers that if a staff were as long as to reach from the Sun to us it would have the same effect in a moment of time Although for my part I am hard to believe we could receive an advertisement so far unless the staff were of such a thickness as being proportionable to the length might keep it from facile bending for if it should be very plyant it would do us no service as we experience in a thrid which reaching from our hand to the ground if it knock against any thing makes no sensible impression in our hand So that in fine reason sense and authority all of them shew us that the less the atomes should penetrate into a moving body by reason of the extreme density of it the more efficaciously they would work and the greater celerity they would cause in its motion And hence we may give the fullest solution to the objection above Which was to this effect that seeing division is made only by the superficies or exteriour part of the dense body and the virtue whereby a dense body works is onely its resistance to division which makes it apt to divide it would follow that a hollow bowl of brass or iron should be as heavy as a solid one For we may answer that seeing the atoms must strike through the body and a cessible body doth not receive their strokes so firmly as a stiffe one nor can convey them so far if to a stiff superficies there succeed a yielding inside the strokes must of necessity lose much of their force and consequently cannot move a body full of air with so much celerity or with so much efficacy as they may a solid one But then you may peradventure say that if these strokes of the descending atomes upon a dense body were the cause of its motion downwards we must allow the atomes to move faster then the dense body that so they may still overtake it and drive it along and enter into it whereas if they should move slower then it none of them could come in their turn to give it a stroke but it would be past them and out of their reach before they
coms as easily as the very air So that in this example as wll as in the other nature teaches us that gravity is no quality And all or most of the arguments which we have urg'd against the quality of gravity in that explication we have consider'd it in have force likewise against it although it be said to be an Inclination of its subject to move it self to unity with the main stock of its own nature as divers witty men put it For this supposition doth but change the intention or end of gravity and is but to make it another kind of intellectual or knowing Entity that determines it self to an other end which is as impossible for a natural quality to do as to determine it self to the former ends And thus much the arguments we have proposed do convince evidently if they be apply'd against this opinion CHAP. XII Of Violent Motion ANd thus we have given a shortscantling wherby to understand in some measure the causes of that motion we call natural by reason it has its birth from the universal Oeconomy of nature here among us that is from the general working of the Sun wherby all natural things have their course and by reason that the cause of it is at all times and in all places constantly the same Next which the order of discourse leads us to take a survey of those forced motions whose first causes the more apparent they are the more obscurity they leave us in to determine by what means they are continued When a Tennis-ball is stroken by a Racket or an Arrow shot from a Bow we plainly see the causes of their motion namely the strings which first yielding and then returning with a greater celerity cause the missives to speed so fast towards their appointed homes Experience informs us what qualities the missives must be endued with to move fast and stedily They must be so heavy that the air may not break their course and yet so light that they may be within the command of the stroke which gives them motion the striker must be dense and in its best velocity the angle which the missive is to mount by if we will have it go to its furthest randome must be the half of a right one and lastly the figure of the missive must be such as may give scope to the air to bear it up and yet not hinder its course by taking too much hold of it All this we see But when with all we see that the mover deserts the moveable assoon as he has given the blow we are at a stand and know not where to seek for that which afterwards makes it flie For motion being a transient not a permanent thing assoon as the cause ceases that begot it in that very point it must be at an end and as long as the motion continues there must be some permanent cause to make it do so so that as soon as the Racket or bow string go back and leave the ball or arrow why should not they presently fall straight down to the ground Aristotle and hs followers have attributed the cause hereof to the air but Galileo relishes not this conception His arguments against it are as I remember to this tenor Frst air by reason of its rarity and divisibility seems not apt to conserve motion next we see that light things are best carried by the air and it has no power over weighty ones lastly it is evident that air takes most hold of the broadest superficies and therfore an arrow would fly faster broad waies then long waies if this were true Nevertheless since every effect must have a proportionable cause from whence it immediately flows and a body must have another body to thrust it on as long as it moves let us examin what bodies touch a moveable whilst it is in motion as the only means to find an issue out of this difficulty for to have recourse to a quality or impressed force for deliverance out of this straight is a shift that will not serve the turn in this way of discourse we use In this Philosophy no knot admits such a solution If then we enquire what body 't is that immediately touches the ball or arrow while it flies we shall find none others does so but the air and the atoms in it after the strings have given their stroke and are parted from the missive And though we have Galileo's authority and arguments to discourage us from believing the air can work this effect yet since there is no other body besides it left for us to consider in this case let us at the least examin how the air behaves it self after the stroke is given by the strings First then t is evident that as soon as the rocket or bow-string shrinks back from the missive and leavs a space between the missive and it as 't is clear it does assoon as it has strucken the resisting body the air must needs clap in with as much velocity as they retire and with somwhat more because the missive goes forward at the same time and therefore the air must hasten to overtake it least any vacuity should be left between the string and the arrow 'T is certain likewise that the air on the sides also upon the division of it slides back and helps to fill that space which the departed arrow leaves void Now this forcible closing of the air at the nock of the arrow must needs give an impulse or blow upon it If it seem to be but a little one you may consider 't is yet much greater then what the air and the bodies swiming in it at the first give to a stone falling from high and how at the last those little atoms that drive a stone in its natural motion with their little blows force it peradventure more violently and swiftly than any impelling agent we are acquainted with can do So that the impulse which they make on the arrow pressing violently upon it after such a vehement concussion and with a great velocity must needs cause a powerful effect in that which of it self is indifferent to any motion any way But unless this motion of the air continue to beat still upon the arrow it will soon fall to the ground for want of a cause to drive it forward and because the natural motion of the air being then the only one will determine it downwards Let us consider then how this violent rending of the air by the blow the bow-string gives to the Arrow must needs disorder the little atones that swim to and fro in it and that being heavier then the air are continually descending downwards This disorder makes some of the heavier parts of them get above others that are lighter then they which they not abiding presse upon those that are next them and they upon their fellows so that there is great commotion and undulation caused in the whole masse of air round about the arrow which must
continue some time before it can be settled and it being determin'd by the motion of the arrow that way that it slides it follows that all this commotion and undulation of the air serves to continue the arrow in its flight And thus faster then any part behind can be setled new ones before are stir'd till the resistance of the medium grows stronger then the impulse of the movers Besides this the arrow pressing on the air before it with a greater velocity then the air which is a liquid rare body can admit to move all of a piece without breaking it must of necessity happen that the parts of the air immediately before the arrow be driven upon others further off before these can be moved to give place unto them so that in some places the air becomes condens'd and consequently in others rarified Which also the wind we make in walking which will shake a paper pin'd loosly at the wall of a chamber towards which we walk and the cooling air caus'd by faning when we are hot do evidently confirm So that it cannot be doubted but condensation and rarefaction of the air must necessarily follow the motion of any solid body which being admitted 't is evident that a greater disorder and for some remarkable time must necessarily be in the air since it cannot brook to continue in more rarity or density then is natural to it Nor can weighty and light parts agree to rest in an equal height or lowness which the violence of the arrows motion forces them to for the present Therefore it cannot be deni'd but that though the arrow slide away there still remains behind it by this condensation and confusion of parts in the air motion enough to give impulse to the arrow so as to make it continue its motion after the bowstring has left it But here will arise a difficulty which is how this clapping in and undulation of the air should have strength and efficacy enough to cause the continuance of so smart a motion as is an arrow shot from a bow To this I need no other argument for an answer then to produce Galileo's testimony how great a body one single mans breath alone can in due circumstances give a rapid motion to and withal let us consider how the arrow and the air about it are already in a certain degree of velocity that is to say the obstacle that would hinder it from moving that way namely the resistance of the air is taken away and the causes that are to produce it namely the determining of the airs and atomes motion that way are heightned And then we may safely conclude that the arrow which of it self is indifferent to be moved upwards or downwards or forwards must needs obey that motion which is caused in it by the atomes and the air 's pressing upon it either according to the impulse of the string or when the string begins to flag according to the beating that follows the general constitution of nature or in a mixt manner according to the proportions that these two hold to one another Which proportions Galileus in his 4 Dialogue of Motion has attempted to explicate very ingeniously but having miss'd in one of his suppositions to wit that forced motion upon an Horizontal line is throughout uniform his great labours therein have taken little effect towards the advancing the knowledge of nature as he pretended for his conclusions succeed not in experience as Mersenius assures us after very exact trials nor can they in their reasons be fitted to nature So that to conclude this point I find no difficulty in allowing this motion of the air strength enough to force the moveable onwards for sometime after the first mover is sever'd from it and long after we see no motions of this nature endure so that we need seek no further cause for the continuance of it but may rest satisfied upon the whole matter that since the causes and circumstances our reason suggests to us are after mature and particular examination proportionable to the effects we see the doctrine we deliver must be sound and true For the establishing wherof we need not considering what we have already said spend much time in solving Galileo's arguments against it seeing out of what we have set down the answers to them appear plain enough For first we have assign'd causes how the air may continue its motion long enough to give as much impression as is needful to the arrow to make it go on as it does Which motion is not requisite to be near so great in the air behind the arrow that drives it on as what the arrow causes in the air before it for by reason of its density it must needs make a greater impression in the air it cuts then the air causes its motion would do of it self without the mediation of the arrow As when the force of a hand gives motion to a knife to cut a loaf of bread the knife by reason of the density and figure it has makes a greater impression in the loaf then the hand alone would do And this is the same that we declared in the natural motion of a heavy thing downwards to which we assigned two causes namely the beating of the atoms in the air falling down in their natural course to determine it the way it is to go and the density of the body that cutting more powerfully then those atoms can do gives together with their help a greater velocity to the moveable then the atoms of themselves can give Nor imports it that our resolution it aginst the general nature of rare and dense bodies in regard of conserving motion as Galileo objects For the reason why dense bodies conserve motion longer then rare bodies is because in regard of their dividing virtue they get in equal time a greater velocity Wherfore seeing velocity is equal to gravity it follows that resistance works not so much upon them as upon rare bodies and therfore cannot make them cease from motion so easily as it does rare bodies This is the general reason for the conservation of motion in dense bodies But because in our case there is a continual cause which conserves motion in the air the air may continue its motion longer than of it self it would do not in the same part of air which Galileus as it seems aim'd at but in divers parts in which the moveable successively is Which being concluded let us see how the forced motion comes to decrease and be ended To which purpose we may observe that the impression which the arrow receives from the air that drives it forwards being weaker than that which it receiv'd at first from the string by reason that the air is not so dense and therfore cannot strike so great a blow the arrow does not in this second measure of time wherein we consider the impulse given by the air only cut so strongly the air before it nor press so
violently upon it as in the first measure when the string parting from it did beat it forwards for till then the velocity encreases in the arrow as it does in the string that carries it along which proceeds from rest at the fingers loose from it to its highest degree of velocity which is when it arrives to the utmost extent of its jerk where it quits the arrow And therfore the air now doth not so swiftly nor so much of it rebound back from before and clap it self behind the arrow to fill the space that else would be left void by the arrows moving forward and consequently the blow it gives in the third measure to drive the arrow on cannot be so great as the blow was immediately after the strings parting from it which was in the second measure of time and therefore the arrow must needs move slower in the third measure than it did in the second as formerly it moved slower in the second which was the airs first stroke than it did in the first when the string drove it forwards And thus successively in every moment of time as the causes grow weaker weaker by the encrease of resistance in the air before and by the decrease of force in the subsequent air so the motion must be slower and slower till it come to pure cessation As for Galileu's second argument that the air has little power over heavy things and therfore he will not allow it to be the cause of continuing forced motions in dense bodies I wish he could as well have made experience what velocity of motion a mans breath might produce in an heavy bullet lying upon an even hard and slippery plain for a table would be too short as he did how admirable great a one it produced in pendants hanging in the air and I doubt not but he would have granted it as powerful in causing horizontal motions as he found it in the undulations of his pendants Which nevertheless sufficiently convince how great a power air has over heay bodies As likewise the experience of wind-guns assures us that air duly applyed is able to give greater motion to heavy bodies than to light ones For how can a straw or feather be imagin'd possibly to fly with half the violence as a bullet of lead doth out of one of those Engines And when a man sucks a bullet upwards in a perfectly bored barrel of a Gun which the bullet fits exactly as we have mention'd before with what a violence doth it follow the breath and ascend to the mouth of the barrel I remember to have seen a man that was uncautious and sucked strongly that had his foreteeth beaten out by the blow of the bullet ascending This experiment if well look'd into may peradventure make good a great part of this Doctrine we now deliver For the air pressing in behind the bullet at the touch-hole gives it its impulse upwards to which the density of the bullet being added you have the cause of its swiftness and violence for a bullet of wood or cork would not ascend so fast and so strongly and the sucking away of the air before it takes away that resistance which otherwise it would encounter with by the air lying in its way and its following the breath with so great ease shews as we touch'd before that of it self 't is indifferent to any motion when nothing presses upon it to determine it a certain way Now to Galileo's last argument that an arrow should fly faster broad-ways than long-ways if the air were cause of its motion there needs no more to be said but that the resistance of the air before hinders it as much as the impulse of the air behind helps it on So that nothing is gain'd in that regard but much is lost in respect of the figure which makes the arrow unapt to cut the air so well when it flyes broad-ways as when 't is shot long-ways and therfore the air being weakly cut so much of it cannot clap in behind the arrow and drive it on against the resistance before which is much greater Thus far with due respect and with acknowledging remembrance of the many admirable mysteries of nature which that great man hath taught the world we have taken liberty to dipute against him because this difficulty seems to have driven him against his Genius to believe that in such motions there must be allow'd a quality imprinted into the moved body to cause them which our whole scope both in this and all other occasions where like qualities are urged is to prove superfluous and ill grounded in nature and to be but meer terms to confound and leave in the dark whoever is forced to fly to them CHAP. XIII Of three sorts of violent motion Reflection Undulation and Refraction THe motion we have last spoken of because 't is ordinarily either in part or wholy contrary to gravity which is accounted the natural motion of most bodies uses to be call'd violent or forced And thus you have deliver'd you the natures and causes both of Natural and of Forced Motion yet it remains that we advertise you of some particular kinds of this forced motion which seem to be different from it but indeed are not As first the motion of Reflection which if we but consider how forced motion is made we shall find it is nothing else but a forced motion whose line whereon 't is made is as it were snapp'd in two by the encounter of a hard body For even as we see in a spout of water strongly shot against a wall the water following drives the precedent parts first to the wall and afterwards coming themselves to the wall forces them again another way from the wall so the latter parts of the torrent of air which is caused by the force that occasion'd the forced motion drives the former parts first upon the resistant body and afterwards again from it But this is more eminent in light than in any other body because light doth less rissent gravity and so observes the pure course of the stroke better than any other body from which others for the most part decline some way by reason of their weight Now the particular law of reflection is that the line incident the line of reflection must make equal angles with that line of the resistent superficies wch is in the same superficies with themselvs The demonstration wherof that great wit Renatus des Cartes hath excellently set down in his book of Dioptricks by the example of a ball strucken by a Racket against the earth or any resisting body the substance wherof is as follows The motion which we call Undulation needs no further explication for 't is manifest that since a Pendent when 't is removed from its perpendicular will restore it self therto by the natural force of gravity and that in so doing it gains a velocity and therefore cannot cease on a suddain it must needs be
carried out of the force of that motion directly the contrary way till the force of gravity overcoming the velocity it must be brought back again to the perpendicular which being done likewise with velocity it must send it again towards the place from which it fell at the first And in this course of motion it must continue for a while every Undulation being weaker then other till at last it quite ceases by the course of nature setling the air in its due situation according to the natural causes that work upon it And in this very manner also is performed that Undulation we see in water when it is stir'd from the natural situation of its Spherical superficies Galileo hath noted that the time in which the Undulations are made which follow one another of their own accord is the same in every one of them and that as much time precisely is taken up in a pendants going a very short arch towards the end of its vibration as was in its going the greatest arch at the beginning of its motion The reason wherof seems strange to him and he thinks it an accident natural to the body out of its gravity and that this effect convinces it is not the air which moves such bodies Wheras in truth 't is clearly the air which causes this effect Because the air striving at each end where it is furthest from the force of the motion to quiet it self gets at every bout somwhat upon the space and so contracts that into a shorter arch That motion also which we call Refraction and is manifest to sense only in light though peradventure hereafter more diligent searchers of nature may likewise find in such other bodies as are called qualitie as in cold or heat c. is but a kind of Reflexion For there being certain bodies in which the passages are so well order'd with their resistences that all the parts of them seem to permit light passe through them and yet all seem to reflect it when light passes through such bodies it finds at the very entrance of them such resistences where it passes as serve it for a reflecting body and yet such a reflectent body as hinders not the passage through but only from being a staight line with the line incident Wherfore the light must needs take a ply as beaten from those parts towards a line drawn from the illuminant falling perpendicularly upon the resisting superficies and therfore is term'd by Mathematicians to be refracted or broken towards the perpendicular Now at the very going out again of the light the second superficies if it be parallel to the former must needs upon a contrary cause strike it the contrary way which is which is termed from the perpendicular But before we wade any deeper into this difficulty we cannot omit a word of the manner of explicating Refraction which Monsieur des Cartes uses so witty a one as I am sorry it wants success He therefore following the demonstration above given of Reflection supposes the superficies which a ball lights upon to be a thin linen cloth or some other such matter as will break cleanly by the force of the ball striking smartly upon it And because that superficies resists only one way therfore he infers that the velocity of the ball is lessen'd only one way and not the other so that the velocity of its motion that way in which it finds no resistance must be after the balls passage through the linnen in a greater proportion to the velocity which it has the other way were it finds resistance then it was before And therfore the ball will in less time arrive to its period on the one side then on the other and consequently lean towards that side to which the course wherin it findes no opposition carries it Which to shew how it is contrary to his own principle Let us conceive the cloth CE to be of some thickness and so draw the line OP to determine that thickness And let us make from B upon AL another Parallelogram like the Parallelogram AL whose Diameter shall be BQ And it must necessarily follow that the motion from B to Q if there were no resistance were in the same proportion as from A to B. But the proportion of the motion as from A to B is the proportion of CB to CA that is it goes in the same time faster towards D then towards M in proportion which CB hath to CA. By which account the resistance it has in the way towards D must also be greater then the resistance it has in the towards M in the proportion which CB has to CA and therfore the more tardicy must be in the way to D and not in the way to M and consequently the declination must be from E wards and to M wards For where there is most resistance that way likewise must the tardity be greatest and the declination must be from that way but which way the thickness to be passed in the same time is most that way the resistance is greatest and the thickness is clearly greater towards E then towards M therfore the resistance must be greatest towards E and consequently the declination from the line BL must be towards M and not towards E. But the truth is in his Doctrine the ball would go in a straight line as if there were no resistance unless peradventure towards the contrary side of the cloth at which it goes out into the free air For as the resistance of the cloth is greater in the way towards D then in the way towards M because it passes a longer line in the same time as also it did formerly in the air so likewise is the force that moves it that way greater then the force which moves it the other And therfore the same proportions that were in the motion before it came to the resisting passage will remain also in it at least till coming near the side at which it goes out the resistance be weakned by the thinness of the resistent there which because it must needs happen on the side that has least thickness the ball must consequently turn the other way where it findes greatest yielding and so at its getting out into the free air it will bend from the greater resistance in such manner as we have said above Neither do the examples brought by Monsieur des Cartes and others in the maintenance of this Doctrine any thing avail them for when a Canon Bullet shot into a River hurts the people on the other side 't is not caused by refraction but by reflection as Monsir des Cartes himself acknowledges and therfor has no force to prove any thing in refraction whose Laws are divers from those of pure reflection And the same answer servs against the instance of a Musket bullot shot at a mark under water which perpetually lights higher then the mark though exactly just aim'd at For we knowing that it is the nature of
same point of incidence in a shorter line and a greater angle than another does In both these wayes 't is apparent that a body composed of greater parts and greater pores exceeds bodies of the opposite kind for by reason that in the first kind more light may beat against one part a body in which that happens will wake an appearance from a further part of its superficies wheras in a body of the other sort the light that beats against one of the little parts of it will be so little as 't will presently vanish Again because in the first the part at the incidence is greater the surface from which the reflection is made inwards has more of a plain and straight superficies and consequently reflects at a greater angle than that whose superficies hath more of inclining But we must not pass from this question without looking a little into the nature of those bodies in which refraction is made for if they as well as the immediate causes of refraction likewise favour us it will not a little advance the certainty of our determination To this purpose we may call to mind how experience shews us that great refractions are made in smoke and mists and glasses and thick-bodied waters and Monsir des Cartes adds certain Oyls and Spirits or strong Waters Now most of these we see are composed of little consistent bodies swimming in another liquid body As is plain in smoke and mists for the little bubbles which rise in the water before they get out of it and that are smoke when they get into the air assure us that smoke is nothing else but a company of little round bodies swimming in the air and the round consistence of water upon herbs leavs twigs in a rind or dew gives us also to understand that a Mist is likewise a company of little round bodies that sometimes stand sometimes float in the air as the wind drives them Our very eyes bear witness to us that the thicker sort of waters are full of little bodies which is the cause of their not being clear As for Glass the blowing of it convinces that the little darts of fire which pierce it every way do naturally in the melting of it convert it into little round hollow bodies which in their cooling must settle into parts of the like figure Then for Chrystal and other transparent stones which are found in cold places it cannot be otherwise but that the nature of cold piercing into the main body and contracting every little part in it self this contraction must needs leave vacant pores between part and part And that such transparent stones as are made by heat have the like effect and property may be judg'd out of what we see in Bricks and Tiles which are left full of holes by the operation of the fire And I have seen in bones that have lain a long time in the Sun a multitude of sensible little pores close to one another as if they had been formerly stack all over with subtile sharp needles as close as they could be thrust in by one another The Chymical Oyles and Spirits which Monsir des Cartes speaks of are likely to be of the same composition since such use to be extracted by violent fires for a violent fire is made by the conjunction of many rayes together and that must needs cause great pores in the body it works on and the sticking nature of these spirits is capable of conserving them Out of all these observations it follows that the bodies in which greatest refractions happen are compounded as we have said of great parts and great pores and therfore by only taking light to be such a body as we have described it where we treated of its nature 't is evident the effect we have exprest must necessarily follow by way of reflection and refraction is nothing else but a certain kind of reflection Which last assertion is likewise convinced out of this that the same effects proceed from reflection as from refraction for by reflection a thing may be seen greater than it is in a different place from the true one where it is colours may be made by reflection as also gloating light and fire likewise and peradventure all other effects which are caused by refraction may as well as these be perform'd by reflection And therfore 't is evident they must be of the same nature since children are the resemblances of their parents CHAP. XIV Of the composition qualities and generation of mixed bodies HAving now declar'd the vertues by which Fire and Earth work upon one another and upon the rest of the Elements which is by Light and the motions we have discours'd of Our task shall be in this Chapter first to observe what will result out of such action of theirs and next to search into the ways and manner of compassing and performing it Which latter we shall the more easily attain to when we first know the end that their operation levels at In this pursuit we shall find that the effect of the Elements combinations by means of the motions that happen among them is a long pedegree of compounded qualities and bodies wherein the first combinations like marriages are the breeders of the next more-composed substances and they again are the parents of others in greater variety and so are multiplied without end for the further this work proceeds the more subjects it makes for new business of the like kind To descend in particular to all these is impossible And to look further then the general heads of them were superfluous and troublesome in this discourse wherin I aim only at shewing what sorts of things in common may be done by Bodies that if hereafter we meet with things of another nature and strain we may be sure they are not the off-spring of bodies and quantity which is the main scope of what I have design'd here And to do this with confidence certainty requires of necessity this leisurely and orderly proceeding we have hitherto used and shall continue to the end For walking thus softly we have always one foot upon the ground so as the other may be sure of firm footing before it settle Wheras they that for more hast will leap over rugged passages and broken ground when both their feet are in the air cannot help themselvs but must light as chance throws them To this purpose then we may consider that the qualities of bodies in common are of three sorts For they are belonging either to the Constitution of a compounded body or else to the Operation of it and the Operation of a body is of two kinds one upon Other Bodies the other upon Sense The last of these three sorts of qualities shall be handled in a peculiar Chapter by themselvs Those of the second sort wherby they work upon Other bodies have been partly declar'd in the former chapters and will be further discours'd of in the rest of this first
in bulk but the small ones very hardly Next the smalness and well-working of the parts by means of the airs penetrating every dense one and sticking close to every one of them and consequently joyning them without any unevenness causes that there can be no ruggedness in it and therfore 't is glibb in like manner as we see plaister or starch become smooth when they are well wrought Then the humidity of it causes it to be catching and the shortness of every part makes that where it sticks it is not easily parted thence Now the rarity of air next to fire admits it to be of all the other Elements most easily brought to the height of fire by the operation of fire upon it And therfore oyls are the proper food of that Element And accordingly we see if a drop of oyl be spill'd upon a sheet of paper and the paper set on fire at a corner as the fire comes near the oyl the oyl will disperse and spread it self upon the paper to a broader compass then it had because the heat rarifies it and so in Oyl it self the fire rarifying the air makes it penetrate the earthy parts adjoynd to it more then it did and so subtilizes them till they be reduced to such a height as they are within the power of fire to communicate its own nature to them and thus it turns them into fire and carries them up in its flame But if fire be predominant over earth and air in a watry compound it makes the body so proportion'd to be subtile rare penetrative hot in operation light in weight and subject to burn Of this kind are all sorts of wines and distil'd Spirits commonly called strong waters or Aquavites in Latine Aquaeardentes These will lose their virtues meerly by remaining uncover'd in the air for fire doth not incorporate strongly with water but if it find means raises it self into the air As we see in the smoke of boyling water which is nothing else but little bodies of fire that entring into the water rarifie some parts of it but have no inclination to stay there and therefore as fast as they can get out fly away but the humide parts of the water which they have rarified being of a sticking nature joyn themselves to them and ascend in the air as high as the fiery atomes have strength to carry them which when it fails them that smoke falls down in a dew and so becomes water again as it was All which one may easily discern in a glasse-vessel of water set over the fire in which one may observe the fire come in at the bottome and presently swim up to the top like a little bubble and immediately rise from thence in smoke and that will at last convert it self into drops and settle upon some solid substance thereabouts Of these fiery spirits some are so subtile as of themselves they will vanish and leave no residue of a body behind them and Alchymists profess to make them so etherial and volatile that being pour'd out of a glass from some reasonable height they shall never reach the ground but before they come thither be so rarified by that little motion as they shall grow invisible like the air and dispersing themselves all about in it fill the chamber with the smell of that body which can no longer be seen The last excess in watery bodies must be of water it self which is when so little a proportion of any of the other is mingled with it as is hardly perceptible Out of this composition arise all those several sorts of juices or liquors we commonly call Waters which by their mixture with the other three Elements have peculiar properties beyond simple Elemental water The general quality whereof we shall not need any further to express because by what we have already said of water in common they are sufficiently known In our next survey we will take Earth for our ground to work upon as hitherto we have done water which if in any body it be in the utmost excess beyond all the other three then rocks and stones will grow out of it whose driness and hardness may assure us that Earth sways in their composition with the least allay that may be Nor doth their lightness in respect of some other earthy compositions impeach this resolution for that proceeds from the greatness and multiplicity of pores wherwith their driness causes them to aboundâ— and hinders not but that their real solid parts may be very heavy Now if we mingle a considerable proportion of water with earth so as to exceed the fire and air but still inferiour to the earth we shall poduce metals whose great weight with their ductility and malleability plainly tells us that the smallest of waters gross parts are the glew that holds the earthy dense ones together such weight belonging to earth and that easie changing of parts being most proper to water Quick-silver that is the general matter wherof all the metals are immediately composed gives us evidence hereof for fire works upon it with the same effect as upon water And the calcination of most of the metals proves that fire can easily part and consume the glew by which they were closed and held together which therfore must be rather of a watry then of an aiery substance Likewise the glibness of Mercury and of melted metals without catching or sticking to other substances gives us to understand that this great temper of a moist Element with earth is water and not air and that the watry parts are comprised and as it were shut up within the earthy ones for air catches and sticks notably to all things it touches and will not be imprisoned the divisibility of it being excceeding great though in never so short parts Now if air mingles it self with earth and be prodominant over water and fire it makes such an oily and fat soil as Husbandmen account their best mould which receiving a betterment from the Sun temperate heat assures us of the concourse of the aire for wherever such heat is air cannot fail of accompanying or being effected by it and the richest of such earth as pot-earth and marl will with much fire grow more compacted and stick closer together then it did as we see in baking them into pots or fine bricks Whereas if water were the glew between the dense parts fire would consume it and crumble them asunder as it doth in those bodies it calcines And excesse of fire will bring them to vitrification which still confirms that air abounds in them for it is the nature of air to stick so close where once it is kneaded in as it cannot be separated without extreme difficulty And to this purpose the viscuous holding together of the parts of glass when it is melted shews evidently that air abounds in vitrified bodies The last mixture we are to meddle with is of fire with earth in an over-ruling
either losing his course by steering after a wrong compass or being forced back again with short and obscure relations of discoveries since others that went out before him are return'd with a large account to such as are able to understand and sum it up Which surely our learned Countryman and my best and most honoured Friend and to whom of all men living I am most obliged for to him I ow that little which I know and what I have and shall set down in all this discourse is but a few sparks kindled by me at his great fire has both profoundly and accutely and in every regard judiciously performed in his Dialogues of the World Our task then in a lower strain and more proportionate to so weak shoulders is to look no further then among those bodies we converse with Of which having declared by what course and Engines Nature governs their common motions that are found even in the Elements and from thence are derived to all bodies composed of them we intend now to consider such motions as accompany divers particular bodies and are much admired by whoever understands not the the causes of them To begin from the easiest and most connexed with the actions of the Elements the handsel of our labour will light upon the motions of Rarefaction and Condensation as they are the passions of mixed bodies And first for Rarefaction we may remember how it proceeds originally from fire and depends of heat as is declared in the former Chapter and wherever we find Rarefaction we may be confident the body which suffers it is not without fire working upon it From hence we may gather that when the Air imprison'd in a baloon or bladder swells against what contains it and stretches its case and seeks to break out this effect must proceed from fire or heat though we see not the fire working either within the very bowels of the air or without by pressing upon what contains it and so making it self a way to it And that this latter way is able to work this effect may be convinced by the contrary effect from a contrary cause for ' take a bladder stretch'd out to its greatest extent by air shut up within it and hang it in a cold place you will see it presently contract it self into a less room and the bladder will grow wrinckled and become too big for the air within it But for immediate proof of this position we see that the addition of a very smal degree of heat rarifies the air in a Weather-glass the air receiving the impression of heat sooner then water and so makes it extend it self into a greater place and consequently it presses upon the water and forces it down into a less room then formerly it possessed And likewise we see Quicksilver and other liquors if they be shut up in glasses close stop'd and set in sufficient heat and a little is sufficient for this effect will swell and fill their glasses and at the last break them rather then not find a way to give themselvs more room which is then grown too straight in the glass by reason of the rarefaction of the liquors by the fire working upon them Now again that this effect may be wrought by the inward heat that is inclosed in the bowels of the substance thus shut up both reason and experience assure us For they teach us that if a body which is not extremely compacted but that by its loosness is easily divisible into little parts such a one as Wine or other spiritual liquors be inclosed in a vessel the little atoms that perpetually move up and down in every space of the whole World making their way through every body will set on work the little parts in the Wine for example to play their game so that the hot and light parts if they be many not enduring to be compressed and kept in by the heavie and cold ones seek to break out with force and till they can free themselvs from the dense ones that would imprison them they carry them along with them and make them swell out as well as themselvs Now if they be kept in by the vessel so that they have not play enough they drive the dense ones like so many little hammers or wedges against the sides of it and at length break it and so make themselvs way to a larger room But if they have vent the more fiery hot spirits fly away and leave the other grosser parts quiet and at rest On the other side if the hot and light parts in a liquor be not many nor very active and the vessel be so ful that the parts have not free scope to remove and make way for one another there will not follow any great effect in this kind as we see in Bottle Beer or Ale that works little unless there be some space left empty in the bottle And again if the vessel be very much too big for the liquor in it the fiery parts find room first to swel up the heavie ones and at length to get out from them though the vessel be close stopped for they have scope enough to float up and down between the surface of the liquor and the roof of the vessel And this is the reason that if a little beer or small wine be left long in a great cask be it never so close stop'd it will in time grow dead And then if at the opening of the bung after the cask hath been long unstir'd you hold a candle close to it you shall at the instant see a flash of flame environing the vent Which is no other thing but the subtile spirits that parting from the beer or wine have left it dead and flying abroad as soon as they are permited are set on fire by the flame they meet with in their journey as being more combustible because more subtile then that spirit of wine which is kept in form of liquor and yet that likewise though much grosser is set on fire by the touch of flame And this happens not only to Wine and Beer or Ale but even to water As dayly experience shews in the East Indian Ships that having been five or six yeers at Sea when they open some of their casks of Thames Water in their return homewards for they keep that water till the last as being their best and most durable and that grows lighter and purer by the often purifyings through violent motions in storms every one of which makes new gross and earthy parts fall down to the bottom and other volatile ones ascend to the top a flame is seen about their bungs if a candle be near as we said before of wine And to proceed with confirming this doctrine by further experience we dayly see that the little parts of heat being agitated and brought into motion in any body enter and pierce into other parts and incorporate themselvs with them and set them on fire if they be capable
may be drawn to what height one pleases However the force which nature applies to maintain the continuity of quantity can have no limit seeing it is grounded upon contradiction And therefore Galileo was much mistaken when he thought to make an instrument wherby to discover the limits of this force We may then conclude that the breaking of the water must depend from the strength of other causes As for example when the gravity is so great by increasing the bulk of the water that it will either overcome the strength of the pipe or else make the sucker of the pump rather yield way to air then draw up so great a weight for which defects if remedies be found the art may surely be inlarged without end This is particular in a Syphon that when that arm of it which hangs out of the water is lower then the superficies of the water then it will run of it self after it is once set on running by sucking The reason whereof is because the weight which is in the water pendant is greater then the weight of the ascending water and therby supplyes the want of a continual suckeâ— But if the nose of that arm that hangs out of the water be put even with the water then the water will stand still in both pipes or arms of the Syphon after thy are filled with sucking But if by the running out of the water the outward pipe grow shorter then to reach as low as the superficies of the water in the fountain from whence it runs in this case the water in each arm of the Syphon will run back into the fountain Withall it is to be noted that though the arm which is out of the water be never so long yet if it reach not lower then the superficies of the fountain the over quantity and weight of the water there more then in the other arm helps it nothing to make it run out Which is because the declivity of the other arm over-recompences this overweight Not that the weight in the shorter pipe has so much force as the weight in the longer pipe but because it has more force then the greater weight exercises therin its running for the greatest part of its force tends another way then to the end of the pipe to wit perpendicularly towards the Centre and so is hindred from effect by the great sloping or little declivity of the pipe upon which it leans But some considering how the water in that longer arm of the Syphon is more in quantity than the water in the other arm of it wherat it runs out admire why the greater quantity of water doth noâ—d raw back the less into the cistern but suffers it self to be lifted up and drain'd away as if it run steeply downwards And they imagine that hence may be deduced that the parts of water in the cistern do not weigh as long as they are within the orb of their own body To whom we answer that they should consider how that to have the greater quantity of water in the longer arme of the Syphon which arm is immersed in the water of the cistern draw back into the cistern the water in the other arm of the Syphon that hangs out in the air it must both raise as much of the water of the cistern as its own bulk is above the level which at present the whole bulk of water has and withal at the same time pull up the water in the other arm Now 't is manifest that these two quantities of water together are heavier then the water in the sunk arm of the Syphon since one of them single is equal unto it And by consequence the more water in the sunk arm cannot weigh back the less water in the hanging arm since to do that it must at the same time weigh up over and above as much more in the cistern as it self weighs But turning the argument I say that if once the arm of the Syphon that is in the air be supposed to draw any water be it never so little out of the cistern whether occasioned by sucking or by whatever other means it follows that as much water as is drawn up above the level of the whole bulk in the cistern must needs press into the sunken arm from the next adjacent parts that is from the bottom to supply its emptying and as much must of it self press down from above according to its natural course when nothing violents it to rest in the place that the ascending water which is lower then it leavs at liberty for it to take possession of And then it cannot be doubted but that this descending water having all its weight in pressing down applied to drive up the rising water in the sunk arm of the Syphon the water in the other arm of the Syphon without having all its weight in ruÌ„ning out appli'd at the same time to draw up the same water in the sunk arm this single resistant must yield to their double mastering force And consequently the water in the arm of the Syphon that is in the air must needs draw the water that is the other immersed arm as long as the end of its pipe reaches lower then the level of the water in the cistern for so long it appears by what we have said it must needs be more weighty since part of the rising water in the sunk arm of the syphon is couÌ„ erpois'd by as much descending water in the cistern And thus 't is evident that out of this experiment it cannot be infer'd that parts of water do not weigh within the orb of their own whole but only that two equal parts of water in their own orb namely that which rises in the sunken arm and that which presses down from the whole bulke in the cistern are of equal weight and ballance one another So that never so little odds between the two counterpoysing parcels of water which are in the air must needs make the water run out at that end of the syphon where the overweight of water is The Attraction whose cause next to this is most manifest is that which is made by the force of heat or fire for we see that fire ever draws air to it so notably that if in a close room there be a good fire a man that stands at the door or window especially without shall hear such a noise that he will think there is a great wind within the chamber The reason of this attraction is that fire rarifying the air next it and withall spending it self perpetually causes the air and his own body mingled together to fly up through the chimney or by some other passage Whence it follows of necessity that the next body must succeed into the place of the body that is flown away The next body generally is air whose mobility and fluidity beyond all other bodies makes it of all others the fittest to be drawn and the more of it
is drawn the more must needs follow Now if there be floating in this air any other atoms subject to the current which the air takes they must also come with it to the fire and by it be rarified and exported out of that little orb Hence it is that men with very good reason hold that fire airs a chamber as we term it that is purifies it both because it purifies it as wind doth by drawing a current of air into it that sweeps through it or by making it purifie it self by motion as a stream of water doth by running as also because those vapours which approach the fire are burned dissolv'd So that the air being noisome and unwholesome by reason of its grossness proceeding from its standing unmoved like a stagnation of dead water in a marish place the fire takes away that cause of annoyance By this very rule we learn that other hot things which participate the nature of fire must likewise in other respects have a resemblance in this quality And accordingly we see that hot loaves in a Bakers shop newly drawn out of the Oven are accounted to draw to them any infection which is in the air The like we say of onyons and other strong breathing substances which by their smel shew much heat in them In like manner 't is conceiv'd that Pigeons and Rabbets and Cats easily take infection by reason of their extraordinary warmth which they have in themselvs And this is confirm'd by the practise of Physitians who use to lay warm Pigeons newly killed to the feet wrists or heads of sick persons and young Puppies to their stomacks and somtimes certain hot gums to their navels to draw out such vapours or humours as infest the body for the same reason they hang amulets of arsenick sublimate dryed Toads or Spiders about their patients necks to draw to them venimous qualities from their bodie Hence also it is that if a man be strucken by a Viper or a Scorpion they use to break the body of the beast it self that stung him if they can get it upon the wound but if the beast be crawl'd out of their finding they do the like by some other venimous creature as I have seen a bruised Toad laid to the biting of a Viper And they manifestly perceive the apply'd body to swel with the Poyson suck'd out from the wound the patient to be reliev'd have less poyson in the same manner as by cupping-glasses the poyson is likewise drawn out from the wound so that you may see the reason of both is the very same or at least very like one another Only we are to note that the proper body of the beast out of which the venome was driven into the wound is more efficacious than any other to suck it out And the like is to be observ'd in all other kinds that such vapours as are to be drawn come better and incorporate faster in bodies of like nature then in those which have only the common conditions of heat and dryness the one of which serves to attract the other to fasten and incorporate into itself the moisture which the first draws to it So we see that water soaks into a dry body whence it was extracted almost inseparably and is hidden in it as when it rains first after hot weather the ground is presently dried after the shower Likewise we see that in most cements you must mingle a dust of the nature of the things which are to be cemented if you will have them bind strongly Out of this discourse we may yield a reason for those Magical operations which some attribute to the Devils assistance peradventure because mans wickedness hath bin more ingenious then his good will and so has found more means to hurt then to help nay when he hath arrived some way to help those very helps have undergone the same calumny because of the likeness which their operations have to the others Without doubt very unjustly if there be truth in the effects For where have we any such good suggestions of the enemy of mankind proposed to us that we may with reason believe he would duly settledly and constantly concur to the help and service of all those he so much hates as he must needs do if he be the Author of such effects Or is it not a wrong to Almighty God and to his careful instruments rather to impute to the Devil the aids which to some may seem supernatural then to them of whom we may justly believe and expect such good Offices and assistances I mean those operations both good and bad which ordinarily are called Magnetical though peradventure wrongfully as not having that property whcih denominates the loadstone One thing I may assure that if the reports be true they have the perfect imitation of nature in them As for example that the Weapons-Salve or the Sympathetick-Powder requires in the using it to be conserved in an equal moderate temper and that the weapon which made the wound or the cloth upon which the blood remains that issued from it be orderly and frequently dressed or else the wounded person will not be cured Likewise the steam or spirits which at the giving of the wound enter'd into the pores of the weapon must not be driven out of it which will be done by fire and so when it is heated by holding over coals you may see a moisture sweat out of the blade at the opposite side to the fire as far as it entred into the wounded persons body which being once all sweated out you shall see no more the like steam upon the sword neither must the blood be washed out of the bloudy cloth for in these cases the powder or salve will work nothing Likewise if there be any excess either of heat or cold in keeping the medicated weapon or cloth the patient feels that as he would do if the like excess where in any remedy that were applyed to the wound it self Likewise if the medicated weapon or bloudy cloth be kept too close no effect follows Likewise the natures of the things used in these cures are of themselves soveraign for healing the like griefs though peradventure too violent if they were apply'd in body without much attenuation And truly if we will deny all effects of this kind we must in a manner renounce all humane faith men of all sorts and qualities and many of them such in my own knowledge as I cannot question their prudence in observing or their sincerity in relating having very frequently made experience of such medicines and all affirming after one fashion to have found the same effects Adde to these the multitude of other like effects appearing or conceited to appear in other things In some Countries 't is a familiar disease with Kine to have a swelling in the soles of their feet and the ordinary cure is to cut a turf upon which they have troden with their sore foot and to hang
a strong bituminous smel in them All which circumstances shew that this electrical virtue consists in a certain degree of rarity or density of the bodies unctuous emanations Now if these refined and viscuous thrids of Jet or Amber in their streaming abroad meet with a piece of straw or hay or dried leaf or some such light and spungy body 't is no marvel if they glew themselvs to it like birdlime and that in their shrinking back by being condens'd again and repuls'd through the coldness of the air they carry it along with them to their entire body Which they that only see the effect and cannot penetrate into a possibility of a natural cause therof are much troubled withal And this seems to me to bear a fairer semblance of truth then what Cabeus delivers for the cause of Electrical attractions whose speculation herein though I cannot allow for solid yet I must for ingenious And certainly even errours are to be commended when they are witty ones and proceed from a casting-further-about then the beaten Tract of verbal learning or rather terms which explicate not the nature of the thing in question He sayes that the coming of straws and such other light bodies to Amber Jet and the like proceeds from a wind raised by the forcible breaking out of subtile emanations from the Electrical bodies into the air which brings those light bodies along with it to the Electrical ones But this discourse cannot hold For First 't is not the nature of unctuous emanation generally speaking to cause smart motions singly of themselvs Secondly although they should raise a wind I do not comprehend how this wind should drive bodies directly back to the source that raised it but rather any other way and so consequently should drive the light bodies it meets with in its way rather from then towards the Electrical body Thirdly if there should be such a wind raised and it should bring light bodies to the Electrical ones yet it could not make them stick therto which we see they do turn them which way you will as though they were glew'd together Neither do his experiences convince any thing For what he saies that the light bodies are somtimes brought to the Electrical body with such a violence that they rebound back from it and then return again to it makes rather against him for if wind were the cause of their motion they would not return again after they had leaped back from the Electrical body no more then we can imagine that the wind it self doth The like is of his other experience when he observ'd that some little grains of Saw-dust hanging at an Electrical body the furthermost of them not only fell off but seem'd to be driven away forcibly for they did not fall directly down but side-wayes and besides flew away with a violence and smartness that argued some strong impulse The reason wherof might be that new emanations might smite them which not sticking and fast'ning upon them wherby to draw them nearer must needs push them further or it might be that the emanations to which they were glew'd shrinking back to their main body the later grains were shoulder'd off by others that already besieg'd the Superficies and then the emanations retiring swiftly the grains must break off with a force or else we may conceive it was the force of the air that bore them up a little which made an appearance of their being driven away as we see feathers and other light things descend not straight down CHAP. XX. Of the Loadstones generation and its particular motions THere is yet remaining the great Mystery of the Loadstone to discourse of Which all Authors both ancient and modern have agreed upon as an undeniable example and evidence of the shortness of mans reach in comprehending and of the impossibility of his reason in penetrating into and explicating such secrets as nature hath a mind to hide from us Wherfore our Reader I am sure will not in this subject expect clear satisfaction or plain demonstrations at our hands but will judg we have fairly acquitted our selves if what we say be any whit plausible Therefore to use our best indeavours to content him let us reflect upon the disposition of parts of this habitable Globe wherof we are Tenants for life And we shall find that the Sun by his constant course under the Zodiack heats a great part of it unmeasurably more then he doth the rest And consequently that this Zodiack being in the mid'st between two as it were ends which we call the Poles these Poles must necessarily be extremely cold in respect of the Torrid Zone for so we call that part of the earth which lies under the Zodiack Now looking into the consequence of this we find that the Sun or the Suns heat which reflects from the earth in the Torrid Zone must rarifie the air extremely and according to the nature of all heat and fire must needs carry away from thence many parts of the air and earth sticking to that heat in such sort as we have formerly declared Whence it follows that other air must necessarily come from the Regions towards both the Poles to supply what is carried away from the middle as is the course in other fires and as we have explicated above Especially considering that the air which comes from the Polewards is heavier then the air of the Torrid Zone and therfore must naturally press to be still nearer the earth and so as it were shoulders on the air of the Torrid Zone towards the circumference by rolling into its place and this in great quantities and consequently the polar air must draw a great train after it Which if we consider the great extent of the Torrid Zone we shall easily perswade our selvs must reach on each side to the very Pole For taking from Archimedes that the Spherical Superficies of a portion of a Sphere is to the Superficies of the whole Sphere according as the parts of the axis of that Sphere comprised within the said portion is to the whole axis and considering that in our case the part of the axis comprised within the Torrid Zone is to the whole axis of the earth in about the proportion of 4. to 10 it must of necessity follow that a fire or great heat reigning in so vast an extent will draw air very powerfully from the rest of the world Neither let any man apprehend that this course of the Sun 's elevating so great quantities of Atoms in the Torrid Zone should hinder the course of gravity there For first the medium is much rarer in thâ— Torrid Zone then in other parts of the earth and therfore the force of the descending Atoms needs not be so great there as in other places to make bodies descend there as fast as they do elsewhere Secondly there being a perpetual supply of fresh air from the Polar parts streaming continually into the Torrid Zone it must of
necessity happen that in the air there come Atoms to the Torrid Zone of that grossness that they cannot suddenly be so much rarified as the subtiler parts of air that are there and therfore the more those subtiler parts are rarified and therby happen to be carried up the stronger and the thicker the heavier Atoms must descend And thus this concourse of air from the Polar parts maintains gravity under the Zodiack where otherwise all would be turned into fire and so have no gravity Now who considers the two Hemispheres which by the Equator are divided will find that they are not altogether of equal complexions but that our Hemisphere in which the Northpole is comprised is much dryer then the other by reason of the greater continent of land in this and the vast tract of Sea in the other and therfore the supply which comes from the divers Hemispheres must needs be of different natures that which comes from towards the Southpole being compared to that which comes from towards the North as the more wet to the more dry Yet of how different complexions soever they be you see they are the emanations of one and the same body Not unlike to what nature hath instituted in the rank of Animals among whom the Male and Female are so distinguish'd by heat and cold moisture and drought that nevertheless all belongs but to one nature and that in degrees though manifestly different yet so near together that the body of one is in a manner the same thing as the body of the other Even so the complexions of the two Hemispheres are in such sort different in the same qualities that nevertheless they are of the same nature and are unequal parts of the same body which we call the Earth Now Alchimists assure us that if two extractions of one body meet together they will incorporate one with the other especially if there be some little difference in the complexion of the extractions Whence it follows that these two streams of air making up one continuate floud of various currents â—om one end of the world to the other each stream that come to the Equator from its own Pole by the extraction of the Sun and that is still supply'd with new matter flowing from its own Pole to the Equator before the Sun can sufficiently rarifie and lift up the Atomes that came first Perpendicularly under its beams as it uses to happen in the effects of Physical causes which cannot be rigorously ajusted but must have some latitude in which nature inclines ever rather to abundance then to defect will pass even to the other pole by the conduct of his fellow in case he be by some occasion driven back homewards For as we see in a Bowl or Pail full of water or rather in a Pipe through which the water runs along if there be a little hole at the bottome or side of it the water will wriggle and change its course to creep out at that Pipe especially if there be a little spiggot or quill at the outside of the hole that by the narrow length of it helps in some sort as it were to suck it So if any of the files of the army or floud of Atoms sucked from one of the Poles to the Equator do there find any gaps or chinks or lanes of retiring files in the front of the other poles battalia of atomes they will press in there in such mannner as we have above declared that water doth by the help of a label of cotten and as is exemplyfied in all the attractions of venime by venimous bodies wherof we have given many examples above and they will go along with them the course they go For as when a thick short gilded ingot of silver is drawn out into a long subtile wyre the wyre continuing still perfectly guilded all over manifestly shews that the outside and the inside of the ingot strangely meet together and intermix in the drawing out so this little stream which like an Eddy current runs back from the Equator towards its own Pole will continue to the end still tincted with the mixture of the other Poles atoms it was incorporated with at his coming to the Equator Now that some little rivolets of air and atoms should run back to their own Pole contrary to the course of their main stream will be easy enough to conceive if we but consider that at certain times of the year winds blow more violently and strongly from some determinate part or Rombe of the world then they do at other times and from other parts As for example our East India Marriners tell us of the famous Monsones they find in those parts whch are strong winds that reign constantly six moneths of the year from one polewards and the other six moneths from the other pole beginning precisely about the Suns entring into such a sign or degree of the Zodiac and continue til about its entrance into the opposite degree And in our parts of the world certain smart Easterly or Northeasterly winds reign about the end of March and beginning of April when it seems that some snows are melted by the spring heats of the Sun And other winds have their courses in other seasons upon other causes All which evidently convince that the course of the air and vapours from the poles to the Equator cannot be so regular and uniform but that many impediments and crosses light in the way to make breaches in it and therby to force it in some places to an opposite course In such sort as we see happens in eddy waters and in the course of a tide wherin the stream ruÌ„ning swiftly in the middle beats the edges of the water to the shore and therby makes it run back at the shore And hence we may conclude that although the main course of air atoms for example from North to South in our Hemisphere can never fail of going on towards the Equator constantly at the same rate in gross nevertheless in several particular little parts of it and especially at the edges of those streams that are driven on faster then the rest by an extraordinary and accidental violent cause it is variously interrupted and somtimes intirely stop'd and other times even driven back to the Northwards And if peradventure any man should think that this will not fall out because each stream seems to be always coming from his one Pole to the Equator and therfore will oppose and drive back any bodies that with less force should strive to swim against it or if they stick to them will carry them back to the Equator We answer that we must not conceive the whole air in body doth every where equally incroach from the Polewards upon the Torrid Zone but as it were in certain brooks or rivulets according as the contingency of all causes put together makes it fall out Now then out of what we have said it will follow that since all
through the nose of the Limbeck and falls into the receiver So that if we will say that a Plant lives or that the whole moves it self and every part moves another 't is to be understood in afar more imperfect manner then when we seak of an Animal and the same words are attributed to both in a kind of equivocal sense But by the way I must note that under the title of Plants I include not Zoophytes or Plant Animals that is such creatures as though they go not from place to place and so cause a local motion of their whole substance yet in their parts they have a distinct and articulate motion But to leave comparisons and come to the proper nature of the things Let us frame a conception that not far under the superficies of the earth there were gather'd together divers parts of little mixed bodies which in the whole sum were yet but little and that this little mass had some excess of fire in it such as we see in wet Hay or in muste of wine or in woort of beer and that withal the drought of it were in so high a degree as this heat should not find means being too much compressed to play his game and that lying there in the bosome of the earth it should after some little time receive its expected and desired drink through the benevolence of the heaven by which it being moistned and therby made more pliable and tender and easie to be wrought upon the little parts of fire should break loose and finding this moisture a fit subject to work upon should drive it into all the parts of the little mass and digesting there should make the mass swel Which action taking up long time for its performance in respect of the small increase of bulk made in the mass by the swelling of it could not be hindred by the pressing of the earth though lying never so weightily upon it according to the maxime we have above deliver'd that any little force be it never so little 't is able to overcome any great resistance be it never so powerful if the force multiply the time it works in sufficiently to equalize the proportions of the agent and the resistant This increase of bulk and swelling of the lettle mass will of its own nature be towards all sides by reason of the fire heat that occasions it whose motion is on every side from the centre to the circuÌ„ference but it wil be most efficacious upwards towards the air because the resistance is least that way both by reason of the little thickness of the earth over it as also by reason that the uper part of the earth lies very loose and is exceeding porous through the continual operation of â—e Sun and falling of rain upon it It cannot choose therfore but mount to the air and the same cause that makes it do so presses at the same time the lower parts of the mass downwards But what ascends to the air must be of the hotter and more moist parts of the fermenting mass and what goes downwards must be of his harder and drier parts proportionate to the contrary motions of fire and earth which predominate in these two kinds of parts Now this that is push'd upwards comcoming above ground and being there exposed to Sun and wind contracts thereby a hard and rough skin on its outside but within is more tender in this sort it defends it self from outward injuries of weather whiles it mounts and by thrusting other parts down into the earth it holds it self steadfast that although the wind may shake it yet it cannot overthrow it The greater this Plant grows the more juice daily accrews to it and the heat is encreased and consequently the greater abundance of humours is continually sent up Which when it begins to clog at the top new humours pressing upwards forces a breach in the skin and so a new piece like the main stem is thrust out and begins on the sides which we call a Branch Thus is our Plant amplified till nature not being able still to breed such strong issues falls to works of less labour and pushes forth the most elaborate part of the plants juice into more tender substances but especially at the ends of the branches where abundant humour but at the first not well concocted grows into the shape of a Button and more and better concocted humour succeeding it grows softer and softer the Sun drawing the subtilest parts outwards excepting what the coldness of the air and the roughness of the wind harden into an outward skin So then the next parts to the skin are tender but the very middle of this button must be hard and dry by reason that the Sun from without and the natural heat within drawing and driving out the moysture and extending it from the center must needs leave the more earthy parts much shrunk up hardned by their evaporating out from them which hardning being an effect of fire within and without that bakes this hard substance incorporates much of it self with it as we have formerly declared in the making of salt by force of fire This button thus dilated and brought to this pass we call the Fruit of the Plant whose harder part encloses oftentimes another not so hard as dry The reason whereof is because the outward hardness permits no moisture to soake in any abundance through it and then that which is enclosed in it must needs be much dried though not so much but that it still retains the common nature of the plant This drought makes these inner parts to be like a kind of dust or at least such as may be easily dried into dust when they are bruised out of the husk that incloses them And in every parcel of this dust the nature of the whole resides as it were contracted into a small quantity For the juice which was first in the button and had passed from the root through the manifold varieties of the divers parts of the plant and suffer'd much concoction partly from the Sun and partly from the inward heat imprison'd in that harder part of the fruit is by these passages strainings and concoctions become at length to be like a tincture extracted out of the whole plant and and is at last dried up into a kind of magistery This we call the Seed which is of a fit nature by being buried in the earth and dissolv'd with humour to renew and reciprocate the operation we have thus described And thus you have the formation of a Plant. But a Sensitive Creature being compared to a Plant as a plant is to mixed body you cannot but conceive that he must be compounded as it were of many plants in like sort as a plant is of many mixed bodies But so that all the Plants which concur to make one Animal are of one kind of nature and cognation and besides the matter of which such diversity is to be made must
necessarily that a tender green substance which we call a bud or leaf must appear a little above the earth since tenderness greenness and ascent are the effects of those two principles heat moisture And must not this green substance change from what it was at first by the Sun and Air working upon it as it grows higher till at length it hardens into a stalk All this while the heat in the root sublimes up more moisture which makes the stalk at first grow rank and encrease in length But when the more volatile part of that warm juice is sufficiently depured and sublimed will it not attempt to thrust it self out beyond the stalk with much vigour and smartness And as soon as it meets with the cold air in its eruption will it not be stop'd and thick'ned And new parts flocking still from the root must they not clog that issue and grow into a button which will be a bud This bud being hard'ned at the sides by the same causes which hard'ned the stalk and all the while the inward heat still streaming up not enduring to be long enclosed especially when by its being stop'd it multiplyes it self will it not follow necessarily that the tender bud must cleave and give way to that spiritual juice which being purer then the rest through its great sublimation shews it self in a purer and nobler substance than any that is yet made and so becomes a flower From hence if we proceed as we have begun and weigh all circumstances we shall see evidently that another substance must needs succeed the flower which must be hollow and contain a fruit in it and that this fruit must grow bigger and harder And so to the last period of the generation of new beans Thus by drawing the thrid carefully along through your fingers and staying at every knot to examine how it is tyed you see that this difficult progress of the generation of living creatures is obvious enough to be comprehended and that the steps of it are possible to be set down if one would but take the pains and afford the time that is necessary less then that Philosopher who for so many years gave himself wholy up to the single observing of the nature of Bees to note diligently all the circumstances in every change of it In every one of which the thing that was becoms absolutely a new thing and is endew'd with new properties and qualities different from those it had before as Physicians from their certain experience assure us And yet every change is such as in the ordinary and general course of nature wherin nothing is to be consider'd but the necessary effects following out such Agents working upon such patients in such circumstances 't is impossible that any other thing should be made of the precedent but that which is immediately subsequent to it Now if all this orderly succession of mutations be necessarily made in a Bean by force of sundry circumstances and external accidents why may it not be conceiv'd that the like is also done in sensible creatures but in a more perfect manner they being perfecter substances Surely the progress we have set down is much more reasonable then to conceive that in the meal of the Bean are contain'd in little several similar substances as of a root of a leaf a stalk a flower a cod fruit and the rest and that every one of these being from the first still the same that they shall be afterwards do but suck in more moisture from the earth to swel and enlarge themselvs in quantity Or that in the seed of the male there is already in act the substance of flesh of bone of sinews of veins the rest of those several similar parts which are found in the body of an Animal and that they are but extended to their due magnitude by the humidity drawn from the mother without receiving any substantial mutation from what they were originally in the seed Let us then confidently conclude that all generation is made of a fitting but remote homogenial compounded substance upon which outward Agents working in the due course of nature change it into another substance quite different from the first and make it less homogenal then the first was And other circumstances and agents change this second into a third that third into a fourth and so onwards by successive mutations that still make every new thing become less homogeneal then the former was according to the nature of heat mingling more and more different bodies together till that substance be produced which we consider in the period of all these mutations And this is evident out of many experiences As for example in Trees the bark which is opposed to the North wind is harder thicker then the contrary side which is opposed to the south and a great difference will appear in the grain of the wood even so much that skilful people will by feeling and seeing a round piece of the wood after the Tree is fell'd tell you in what situation it grew and which way each side of that piece look'd And Josephus Acosta writes of a Tree in America that on the one side being situated towards great hills and on the other exposed to the hot Sun the one half of it flourishes at one time of the year and the other half at the opposite season and some such like may be the cause of the strange effects we somtimes see of trees flourishing or bearing leaves at an unseasonable time of the year as in particular in the famous Oak in the New Forrest and in some others in our Island in which peradventure the Soil they grow in may do the same effect as the winds and Sun did in the Tree that Acosta mentions For we daily see how some soiles are so powerful over some kind of corn that they will change the very nature of it so that you shall reap Oats or Rie after you have sown Wheat there Which shews evidently that since the outward circumstances can make the parts or the whole of any substance become different from what they were at first generation is not made by aggregation of like parts to presupposed like ones nor by a specifical worker within but by the compounding of a seminary matter with the juice which accrues to it from without and with the streams of circumstant bodies which by an ordinary course of nature are regularly imbibed in it by degrees and at every degree change it into a different thing such as is capable to result out of the present compound as we have said before till it arrive to its full perfection Which yet is not the utmost period of natures changes for from that for example from corn or an Animal it carries it on still changing it to be meal or a Cadaver from thence to be bread or durt after that to be blood or grass And so still turning about her wheel which suffers nothing to remain
little parts of the substance which we chew in our Teeth and which passes over it You may observe how if we take any herb or fruit and having chop'd or beaten it small put it into a wooden dish of water and squeeze it a little the juice communicating and mingling it self with the water infects it with the tast of it self and remaining a while in the bowl sinks by little and little into the very pores of the wood as is manifest by its retaining a long time after the tast and smell of that herb In like manner nature hath taught us by chewing our meat and by turning it in our mouths and pressing it a little that we may the more easily swallow it to imbue our Spittle with such little parts as easily diffuse themselvs in water And then our Spittle being continuate to the moysture within our tongue in such sort as we declared of the moisture of the earth that soaks into the root of a plant and particularly in the sinews of it must of necessity affect those little sensible strings with the qualities which these petty bodies mixed every where with the moisture are themselves imbued withal And if thou ask what motions or qualities these be Physitians to whom it belongs most particularly to look into them will tell you that some dilate the tongue more and some less as if some of these little bodies had an aereal and others a watry disposition and these two they express by the names of sweet and fatty That some contract and draw the tongue together as choaky and rough things do most and next to them crabby and immature sharpness That some corrode and pierce the Tongue as Salt and sowre things That bitter things search the outside of it as if they swept it and that other things as it were prick it as spices and hot drinks Now all these are sensible material things which admit to be explicated clearly by the varieties of rarity and density concurring to their compositions and are so proportionable to such material instruments as we cannot doubt but they may be throughly declared by our former principles The next Element above Water is Air which our Nostrils being our Instrument to suck in we cannot doubt but what affects a man by his Nose must come to him in Breath or Air. And as humidity receives grosser and weightier parts so those which are more subtile and light rise up into the Air and these we know attain to this lightness by the commixtion of fire which is hot and dry And therfore we cannot doubt but that the nature of Smells is more or less tending to heat and drought which is the cause that their commixtion with the brain proves comfortable to it because of its own disposition it is usually subject to be too moist and too cold Whether there be any immediate instrument of this sense to receive the passion or effect which by it other bodies make upon us or whether the sense it self be nothing but a passage of these exhalations and little bodies to the brain fitly accommodated to discern what is good or hurtful for it and accordingly to move the body to admit or reject them it imports not us at present to determine let Physicians and Anatomists resolve that question Whiles it suffices us to understand that the operations of bodies by Odours upon our sense are perform'd by real and solid parts of the whole substance which are truly material though very little bodies and not by imaginary qualities And those bodies when they proceed out of the same things that yield also tastive particles although without such material violence and in a more subtile manner must of necessity have in them the same nature which those have that affect the tast and they must both of them affect a man much alike by his tast by his smell and so are very proportionate to one another excepting in those properties which require more cold or liquidity then can well stand with the nature of a smell And accordingly the very names which men have imposed to express the affections of both many times agree as savour and sweet which are common both to the smell and tast the strongest of which we see oftentimes make themselves known as well by the one as by the other sense and either of them in excess will turn a mans stomack And the Physicians that write of these senses find them very conformable whence it happens that the losing of one of them is the losse also of the other And experience teaches us in all Beasts that the Smell is given to living creatures to know what meats are good for them and what are not And accordingly we see them still smell for the most part at any unknown meat before they touch it which seldom fails of informing them rightly nature having provided this remedy against the gluttony which could not choose but follow the convenient disposition and temper of their parts and humours through which they often swallow their meat greedily and suddenly without expecting to try it first by their tast Besides that many meats are so strong that their very tasting them after their usual manner would poison or at least greatly annoy them and therfore nature hath provided this sense to prevent their tast which being far more subtile then their tast the final atoms by which it is perform'd are not so very noxious to the health of the Animal as the other grosser atoms are And doubtlesly the like use men would make of this sense had they not on the one side better means then it to know the qualities of meats and therfore this is not much reflected on And on the other side were they not continually stuff'd and clogg'd with gross vapours of streamy meats which are daily reeking from the Table and their stomacks and permit not purer Atomes of bodies to be discerned which require clear and uninfected organs to take notice of them As we see it fare with doggs who have not so true and sensible noses when they are high fed and lie in the kitchin amidst the steams of meat as when they are kept in their kennel with a more spare diet fit for hunting One full example this age affords us in this kind of a man whose extremity of fear wrought upon him to give us this experiment He was born in some Village of the Countrey of Liege and therfore among strangers he is known by the name of John of Liege I have been informed of this story by several whom I dare confidently believe that have had it from his own mouth and have question'd him with great curiosity particularly about it When he was a little boy there being wars in the Countrey as that State is seldom without molestations from abroad when they have no distempers at home which is an inseparable effect of a Countries situation upon the Frontiers of powerful neighbouring Princes that are at variance the
of the instrument which is the reason that the concave figure is affected in most and so when it breaks out of the instrument in greater quantity then the string immediately did shake it causes the same undulations in the whole body of Air round about And that striking the Drum of the ear gives notice therin what tenour the string moves whose vibrations if one stop by laying his finger upon it the sound is instantly at an end for then there is no cause on foot that continues the motion of the Air which without a continuation of the impulse returns speedily to quiet through the resistance made to it by other parts of it that are further off Out of all which 't is plain that motion alone is able to effect and give account of all things whatever that are attributed to Sound and that Sound and motion go hand in hand together so that whatever is said of the one is likewise true of the other Wherfore it cannot be deny'd but that hearing is nothing else but the due perception of motion and that motion and sound are in themselvs one and the same thing though expressâ—d by different names and comprised in our understanding under different notions Which proposition seems to be yet further convinced by the ordinary experience of perceiving musick by mediation of a stick for how should a deaf man be capable of musick by holding a stick in his Teeth whose other end lies upon the Vial or Virginals were it not that the proportional shaking of the stick working a like dancing in the mans head make a like motion in his brain without passing through his ear and consequently without being otherwise sound then as bear motion is sound Or if any man will still persist in having sound be some other thing then as we say and that it effects the sense otherwise then purely by motion he must nevertheless acknowledge that whatever it be it hath neither cause nor effect nor breeding nor dying that we either know or can imagine And then if he will let reason sway he will conclude it unreasonable to say or suspect so ill grounded a surmise against so clear and solid proofs which our ears themselvs not a little confirm their whole figure and nature tending to the perfect receiving conserving and multiplying the motions of air which happen without a man as who is curious may plainly see in the Anatomists books and discourses CHAP. XXIX Of Sight and Colours THere is yet left the object of our Sight which we call Colours to take a survey of for as for light we have at large display'd the nature and properties of it from which whether colour be different or no will be the question we shall next discuss For those who are cunning in Opticks will by refractions and reflexions make all sorts of colours out of pure light as we see in Rainbows in those Triangular Glasses or Prisms which some call Fools Paradises and in other inventions for this purpose Wherfore in brief to shew what colour is let us lay for a ground that Light is of all other things in the world the greatest and the most powerful agent upon our eye either by it self or by what comes in with it and that where light is not darkness is Then consider that light may be diversly cast especially through or from a transparent body into which it sinks in part and in part it doth not and you will conclude that it cannot choose but come out from such a body in divers sorts mingled with darkness Which if it be in a sensible quantity accordingly makes divers appearances and those appearances must of necessity have divers hues representing the colours which are middle colours between white and black since white is the colour of light and darkness seems black Thus those colours are ingendred which are call'd apparent ones And they appear somtimes but in some one position as in the Rainbow which changes place as the looker on doth but at other times they may be seen from any part as those which light makes by a double refraction through a Triangular Glass And that this is rightly deliver'd may be gather'd out of the conditions requisite to their production For that Chrystal or water or any refracting body doth not admit light in all its parts is evident by reason of the reflection it makes which is exceeding great and not only from the superficies but even from the middle of the body within as you may see plainly if you put it in a dark place and enlighten but one part of it for then you may perceive as it were a current of light pass quite through the body although your eye be not opposite to the passage so that manifestly it reflects to your eye from all the inward parts which it lights upon Now a more oblique reflection or refractiom more disperses the light and admits more privations of light in its parts then a less oblique one as Galileo hath demonstrated in the First Dialogue of his Systeme Wherefore a less oblique reflection or refraction may receive that in quality of light which a more oblique one makes appear mingled with darkness and consequently the same thing will appear colour in one which shews it self plain light in another for the greater the inclination of an angle is the greater also is the dispersion of the light And as colours are made in this sort by the medium through which light passes so if we conceive the superficies from which the light reflects to be diversly order'd in respect of reflexion it must of necessity follow that it will have a divers lustre and sight as we see by experience in the necks of Pigeons and in certain positions of our eye in which the light passing through our eye-brows makes an appearance as though we saw divers colours streaming from a candle we look upon And accordingly we may observe how some things or rather most appear of a colour more inclining to white when they are irradiated with a great light then when they stand in a lesser And we see Painters heighten their colours and make them appear lighter by placing deep shadows by them even so much that they will make objects appear nearer and further off meerly by their mixtion of their colours Because objects the nearer they are the more strongly and lively they reflect light and therfore appear the clearer as the others do more dusky Wherfore if we put the superficies of one body to have a better disposition for the reflection of light then another hath we cannot but conceive that such difference in the superficies must needs beget variety of permanent colours in the bodies and according as the superficies of the same body is better or worse disposed to reflection of light by polishing or by compressure together or the like so the same body remaining the same in substance will shew it self of a different colour And it being
end a red will now appear where in the former case a blew appear'd This case we have chosen as the plainest to shew the nature of such colours out of which he that is curious may derive his knowledge to other cases which we omit because our intent is only to give a general doctrine and and not the particulars of the Science and rather to take away admiration than to instruct the Reader in this matter As for the various colours which are made by straining light through a glass or through some other Diaphanous body to discover the causes and variety of them we must examine what things they are that concur to the making of them and what accidents may arrive to those things to vary their product 'T is clear that nothing intervenes or concurs to the producing of any of these colours besides the light it self which is dyed into colour and the glass or Diaphanous body through which it passes In them therfore and in nothing else we are to make our enquiry To begin then we may observe that light passing through a Prism and being cast upon a reflecting object is not alwayes colour but in some circumstances it still continues light and in others it becomes colour Withal we may observe that those beams which continue light and endure very little mutation by their passage making as many refractions make much greater deflexions from the straight lines by which they came into the glass then those Rays do which turn to colour As you may experience if you oppose one surface of the Glass Perpendicularly to a Candle and set a Paper not irradiated by the Candle opposite to one of the other sides of the Glass for upon the paper you shall see fair light shine without any colour and you may perceive that the line by which the light comes to the Paper is almost Perpendicular to that line by which the light comes to the Prism But when light becomes colour it strikes very obliquely upon one side of the glass and comes likewise very obliquely out of the other that sends it in colour upon a reflectent body so that in conclusion there is nothing left us whereon to ground the generation of such colours besides the littleness of the angle and the sloapingness of the line by which the illuminant strikes one side of the Glass and comes out at the other when colours proceed from such a percussion To this then we must wholly apply our selves and knowing that generally when light falls upon a body with so great a sloaping or inclination so much of it as gets through must needs be weak and much diffused it follows that the reason of such colours must necessarily consist in this diffusion and weakness of light which the more it is diffused the weaker it grows and the more lines of darkness are between the lines of light and mingle themselvs with them To confirm this you may observe how just at the egress from the Prism of that light which going on a little further becomes colours no colour at all appears upon a paper opposed close to the side of the Glass till removing it farther off the colours begin to shew themselvs upon the edges therby convincing manifestly that it was the excess of light which hindred them from appearing at the first And in like manner if you put a burning glass between the light and the Prism so as to multiply the light which goes through the Prism to the paper you destroy much of the colour by converting it into light But on the otherside if you thicken the air and make it dusky with smoak or dust you will plainly see that where the light comes through a convex glass perpendicularly opposed to the illuminant there will appear colours on the edges of the cones that the light makes And peradventure the whole cones would appear colour'd if the darkning were conveniently made for if an opacous body be set within either of the cones its sides will appear colour'd though the air be but moderately thickned which shews that the addition of a little darkness would make that which otherwise appears pure light be throughly dyed into Colours And thus you have the true and adequate cause of the appearance of such colours Now to understand what colours and upon which sides will appear we may consider that When light passes through a glass or other Diaphanous body so much of it as shines in the air or upon some reflecting body bigger then it self after its passage through the glass must of necessity have darkness on both sides of it and so be comprised and limited by two darknesses but if some opacous body less then the light be put in the way of the light then it may happen contrariwise that there be darkness or the shadow of that opacous body between two lights Again we must consider that when light falls so upon a Prism as to make colours the two outward Rays which proceed from the light to the two sides of the superficies at which the light enters are so refracted that at their coming out again through the other superficies that Ray which made the less angle with the outward superficies of the glass going in makes the greater angle with the outside of the other superficies coming out and contrariwise that Ray which made the greater angle going in makes the lesser at its coming out and the two internal angles made by those two Rays and the outside of the superficies they issue at are greater then two right angles And so we see that the light dilates it self at its coming out Now because Rays that issue through a superficies the nearer they are to be perpendiculars to that superficies so much the thicker they are it follows that this dilation of light at its coming out of the glass must be made and encrease from that side where the angle was least at the going in and greatest at the coming out so that the nearer to the contrary side you take a part of light the thinner the light must be there and contrariwise the thicker it must be the nearer it is to the side where the angle at the rays coming out is the greater Wherfore the strongest light that is the place where the light is least mixed with darkness must be nearer that side than the other Consequently hereto if by an opacous body you make a shadow comprehended within this light that shadow must also have its strongest part nearer to one of the lights betwixt which it is comprised then to the other for shadow being nothing else but the want of light hindred by some opacous body it must of necessity lie aversed from the illuminant just as the light would have lain if it had not been hindred Wherfore seeing that the stronger side of light more impeaches the darkness then the feebler side doth the deepest dark must incline to that side where the light is weakest that is
disposition for a body that is to be the porter of any simple motion which should always lie watching in great quietness to observe scrupulously and exactly the errand he is to carry So that for my part I cannot conceive nature intended any such effect by mediation of the sinews But Monsir des Cartes endeavours to confirm his opinion by what uses to fall out in Palsies when a man looses the strength of moving his hands or other members nevertheless retains his feeling which he imputes to the remaining intire of the strings of the nerves while the spirits are some way defective To this we may answer by producing examples of the contrary in some men who have had the motion of their limbs intire and no ways prejudiced but no feeling at all quite over their whole case of skin and flesh As particularly a servant in the Colledge of Physitians in London whom the learned Harvey one of his Masters hath told me was exceeding strong to labour and very able to carry any necessary burthen and to remove things dexterously according to the occasion and yet he was so void of feeling that he used to grind his hands against the walls and against course lumber when he was employ'd to rummage any in so much that they would run with blood through grating of the skin without his feeling of what occasion'd it In our way the reason of both these conditions of people the paralytike and the insensible is easie to be rendred For they proceed out of the diverse disposition of the animal spirits in these parts which if they thicken too much and become very gross are not capable of transmitting the subtile messengers of the outward world to the tribunal of the brain to judge of them on the otherside if they be too subtile they neither have nor give power to swell the skin and so to draw the muscles to their heads And surely Monsir des Cartes takes the wrong way in the reason he gives of the Palsie for it proceeds out of abundance of humors which clogging the nerves rendreth them washy and makes them lose their dryness and become lither and consequently unfit and unable in his opinion for sensation which requires stiffness as well as for motion Yet besides all these one difficulty more remains against this doctrine more insuperable if I mistake not then any thing or altogether we have yet said which is how the memory should conserve any thing in it and represent bodies to us when our fancy calleth for them if nothing but motions come into the brain For 't is impossible that in so divisible a subject as the Spirits motion should be conserv'd any long time as we see evidently in the air through which move a flaming Taper never so swiftly and as soon as you set it down almost in the very instant the flame of it leaves being driven or shaken on one side and goes quietly and evenly up its ordinary course Therby shewing that the motion of the air which for the time was violent is all of a sudden quieted and at rest for otherwise the flame of the Taper would blaze that way the Air were moved Assuredly the bodies that have power to conserve motion long must be dry and hard ones Nor yet can such conserve it very long after the cause which made it ceases from its operation How then can we imagine that such a multitude of pure motions as the memory must be stored withal for the use and service of man can be kept on foot in his brain without confusion and for so long a time as his memory is able to extend to Consider a lesson plaid upon the Lute or Virginals and think with your self what power there is or can be in nature to conserve this lesson-over continually playing and reflect that if the impressions upon the common fense are nothing else but such things then they must be actually conserved always actually moving in our head to the end they be immediately produced whenever it pleases our will to call them And if peradventure it should be replyed that 't is not necessary the motions themselvs should always be conserved in actual being but 't is sufficient there be certain causes kept on foot in our heads which are apt to reduce these motions into act whenever there is occasion of them All I shall say hereto is That this is merly a voluntary Position and that there appears no ground for these motions to make and constitute such causes since we neither meet with any instruments nor discover any signs wherby we may be induced to believe or understand any such operation It may be urged that divers sounds are by diseases oftentimes made in our ears and appearances of colours in our fantasie But first these colours and sounds are not artificial ones and disposed and order'd by choice and judgment for no story hath mention'd that by a disease any man ever heard twenty verses of Virgil or an Ode of Horace in his ears or that ever any man saw fair pictures in his fansie by means of a blow givin him upon his eye And secondly such colours and sounds as are objected are nothing else but in the first case the motion of humors in a mans eye by a blow of upon it which humours have the virtue of making light in such sort as we see Sea-water has when it is clash'd together and in the second case a cold vapour in certain parts of the brain which causes beatings or motions there whence proceeds the imitation of sounds so that these examples nothing advantage that party thence to infer that the similitudes of objects may be made in the common-sense without any real bodies reserv'd for that end Yet I intend not to exclude Motion from any commerce with the Memory no more then I have done from Sensation For I will not only grant that all our remembring is perform'd by the means of motion but also acknowledge that in men it is for the most part of nothing else but of motion For what are words but motion And words are the chiefest objects of our remembrance 'T is true we can if we will remember things in their own shapes as well as by the words that express them but experience tells us that in our familiar conversation and the ordinary exercise of our memory we remember and make use of the words rather then of the things themselvs Besides the impressions that are made upon all our other sense as well as upon our hearing are likewise for the most part of thing in motion as if we have occasion to make a conception of a Man or of a Horse we ordinarily conceive him Walking or Speaking or eating or using some motion in time And as these impressions are successively made upon the outward Organs so are they successively carried into the fantasie by like succession are deliver'd over into the memory from whence when they are call'd back
touching Gravity 6. Gravity and levity do not signifie an intrinsecal inclination to such a motion in the bodies themselvs which are term'd heavy and light 7. The more dense a body is the more swiftly it descends 8. The velocity of bodies descending doth not encrease in proportion to the difference that may be between their several densities 9. More or less gravity produces a swister or a slower descending a heavy body Aristotles argument to disprove motion in 〈◊〉 is made good 10. The reason why at the inferior quarter of a circle a body descends faster by the arch of that quarter then by the chord of it 1. The first objection answered why a hollow body descends flower then a solid one 2 The second objection answer'd and the reasons shown why atoms continually overtake the descending dense body 3. A curious queston left undecided 4. The fourth objection answer'd Why the descent of the same heavy bodies is equal in so great inequality of the atoms which cause it 5. The reason why the shelter of a thick-body doth not hinder the descent of that which is under it 6. The reason why some bodies sink others swims 7. The fifth objection answer'd concerning the descending of heavy bodies in streams 8. The sixth objection answered and that all heavy Elements do weigh in their own Spheres 9 The seventh objection answer'd and the reason why we do not feel the course of the air and atoms that beat continually upon us 10. How in the some body gravity may be greater than density and density than gravity though they be the same thing 11. The opinion of gravities being an intrinsecal inclination of a body to the centre refuted by reason â—2 The same opinion refuted by several experiences 1. The State of the question touching the cause of violent motion 2 That the medium is the only cause which continues violent motion 3. A further explication of the former Doctrine 4. That the air has strength enough to continue violent motion in a moveable Dial. 1. of motion pag. 98. 5. An answer to the first objection that air is not apt to conserve motion And how violent motion comes to cease 6. An answer to the second objection that the air has no power over heavy bodies 7. An answer to the third objection that an arrow should fly faster broadways than long ways 1. That reflection is a kind of violent motion 2. Reflection is made at equal angles 3. The causes and properties of Undulation 4. Refraction at the entrance into the reflectent body is towà rds the perpendicular at the going out is from it when the second superficies is parallel to the first 6. An answer to the arguments brought in favovr of Monsir des Cartes his opinion 7. The true cause of refraction of light both at its entrance and at its going out from the reflecting body 8. A general rule to know the nature of reflections and refractions in all sorts of surfaces 9. A body of greater parts and greater pores makes a greater refraction than one of lesser parts and lesser pores 10. A confirmation of the former doctrine out of the nature of bodies that refract light 1. The connexion of this Chapter with the rest and the Authors intent in it 2. That there is a least size of bodies And that this least size is found in fire 3. The first conjunction of parts is in bodies of least size and it is made by the force of Quantity 4. The second sort of conjunction â—s compactedness in simple Elements and it proceeds from Density 5. The third conjunction is of parts of different Elements and it proceeds from quantity and density together 6. The reason why liquid bodies easily joyn together and dry ones difficultly 7. That no two hard bodies can touch one another immediately 8. How mixed bodies are framed in general 9. The cause of the several degrees of solidity in mixed bodies 10. The rule whereto are reduced all the several combinations of Elements in compounding of mixed bodies 11. Earth and water are the Basis of all permanent mixed bodies 12. What kind of bodies those are where water is the Basis and earth the pedominant element over the other two 13. Of these bodies where water bing the B sis air is the predominant Element 14. What kind of bodies result where water is the Basis and fire the predominant Element 15. Of those bodies where water is in excess it alone being both the Basis and the predominant Element 16. Of those bodies were Earth alone is the Basis and also the predominant in excess over the other three Elements 17. Of those bodies where Earth is the basis and Water the predominant Element over the other two 18. Of those bodies where earth being the basis air is the predominant 19. Of those bodies where earth being the basis fire is the predominant 20. All the Second Qualities of mixed bodies arise from several combinations of the First Qualities and are at last resolv'd into several degrees of rarity and density 21. That in the Planets and Stars there is a like variety of mixed bodies caused by light as here upon Earth 22. In what manner the Elements work upon one another in the position of mixed bodies and in particular fire is the most active 23. A particular declaration touching the generation of Metals 1. Why some bodies are brittle and others tough or apt to withstand outward violence the first instrument to dissolve mixed bodies 2. How outward violence work upon the most compacted bodies 3. The several effects of fiâ—e the second and chiefest instrument to dissolve compounded bodies 4. The reason why some bodies are not dissolv'd by fire 5. The reason why fire melts gold but cannot consume it 6. Why Lead is easily consumed and calcined by fire 7. Why and how some bodies are divided by fire into spirits waters oyls salts and earth what those parts are 〈◊〉 How water the third instrument to dissolve bodies dissolves Calx into Salt and so into Terra damnata 9. How water mingled with salt becomes almost powerfull Agent to dissolve other bodies 20. How putrefaction is caused 1. What is the Sphere of Activity in corporeal Agents 2. The reason why no body can work in distance 3. An objection answer'd against the manner of explicating the former Axiome 4 Of reaction and first in pure local motion that each Agent must suffer in acting and act in suffering 5. The former doctrine applyed to other local motions design'd by particular names And that Suisseths argument is of no force against this way of doctrine 6. Why some notions admit of intension and remission and others not 7. That in every part of our habitable world all the four Elements are found pure in smal atoms but not in any great bulk 1. The Authors intent in this and the following chapters Mr. Thomas White 2. That bodies may be rarified both by outward and inward heat and how this is perform'd 3.