think you must happen to the Sea which resteth on it and is a Fluid Body A. I think it must make the Sea rise and fall And the same happeneth also to the Air from the Motion of the Sun B. Remember also in what manner the Sea is situated in respect of the Dry Land A. Is not there a great Sea that reacheth from the Straight of Magellan Eastward to the Indies and thence to the same Straight again And is not there a great Sea called the Atlantick Sea that runneth Northward to us and does not the great South-Sea run also up into the Northern Seas But I think the Indian and the South-Sea of themselves to be greater than all the rest of the Surface of the Globe B. How lieth the water in those two Seas A. East and West and rises and falls a little as it is forc'd to do by this compounded Motion which is a kind of succussion of the Earth and fills both the Atlantick and Northern Seas B. All this would not make a visible difference between High and Low water because this Motion being so regular the unevenness would not be great enough to be seen For though in a Bason the water would be thrown into the Air yet the Earth cannot throw the Sea into the Air. A. Yes The Bason if gently moved will make the water so move that you shall hardly see it rise B. It may be so But you should never see it rise as it doth if it were not checkt For at the Straight of Magellan the great South-Sea is checkt by the shore of the Continent of Peru and Chily and forced to rise to a great height and made to run up into the Northern Seas on that side by the coast of China and at the return is checkt again and forced through the Atlantick into the British and German Seas And this is done every day For we have supposed that the Earths Motion in the Ecliptique caused by the Sun is Annual and that its Motion in the Aequinoctial is Diurnal It followeth therefore from this compounded Motion of the Earth the Sea must Ebb and Flow twice in the space of Twenty four hours or thereabout A. Has the Moon nothing to do in this business B. Yes For she hath also the like Motion And is though less swift yet much neerer to the Earth And therefore when the Sun and Moon are in Conjunction or Opposition the Earth as from two Agents at once must needs have a greater Succussion And if it chance at the same time the Moon also be in the Ecliptique it will be yet greater because the Moon then worketh on the Earth less obliquely A. But when the Full or New Moon happen to be then when the Earth is in the Aequinoctial points the Tides are greater than ordinary Why is that B. Because then the force by which they move the Sea is at that time to the force by which they move the same at other times as the Aequinoctial Circle to one of its Parallels which is a lesser Circle A. 'T is evident And 't is pleasant to see the Concord of so many and various motions when they proceed from one and the same Hypothesis But what say you to the stupendious Tides which happen on the Coasts of Lincolnshire on the East and in the River of Severn on the West B. The cause of that is their proper Scituation For the Current of the Ocean through the Atlantick Sea and the Current of the South-Sea through the Northern Seas meeting together raise the water in the Irish and British Seas a great deal higher than ordinary Therefore the mouth of the Severn being directly opposite to the Current from the Atlantick Sea and those Sands on the Coast of Lincolnshire directly opposite to the Current of the German Sea those Tides must needs fall furiously into them by this Succussion of the water A. Does when the Tide runs up into a River the water all rise together and fall together when it goes out No One part riseth and another falleth at the same time because the Motion of the Earth rising and falling is that which makes the Tide A. Have you any Experiment that shews it B. Yes You know that in the Thames it is high water at Greenwich before it is high water at London-bridge The water therefore falls at Greenwich whilst it riseth all the way to London But except the top of the water went up and the lower part downward it were impossible A. 'T is certain It is strange that this one Motion should salve so many apparences and so easily But I will produce one Experiment of water not in the Sea but in a Glass If you can shew me that the cause of it is this compounded Motion I shall go neer to think it the Cause of all other Effects of Nature hitherto disputed of The Experiment is common and described by the Lord Chancellour Bacon in the third page of his Natural History Take saith he a Glass of water and draw your finger round about the lip of the Glass pressing it somewhat hard after you have done so a few times it will make the water frisk up into a fine Dew After I had read this I tried the same with all diligence my self and found true not onely the frisking of the water to above an inch high but also the whole Superficies to circulate and withal to make a pleasant sound The Cause of the frisking he attributes to a tumult of the inward parts of the Substance of the Glass striving to free it self from the pressure B. I have tried and found both the Sound and Motion and do not doubt but the pressure of the parts of the Glass was part of the Cause But the Motion of my finger about the Glass was always parallel and when it chanced to be otherwise both Sound and Motion ceased A. I found the same And being satisfied I proceed to other questions How is the water being a heavie Body made to ascend in small particles into the Air and be there for a time sustained in form of a Cloud and then fall down again in Rain B. I have shewn already that this compounded Motion of the Sun in one part of its Circumlation drives the Air one way and in the other part the contrary way and that it cannot draw it back again no more than he that sets a stone a flying can pull it back The Air therefore which is contiguous to the water being thus distracted must either leave a Vacuum or else some part of the water must rise and fill the spaces continually forsaken by the Air. But that there is no Vacuum you have granted Therefore the water riseth into the Air and maketh the Clouds and seeing they are very small and invisible parts of the water are though naturally heavie easily carried up and down with the Wind till meeting with some Mountain or other Clouds they be prest together into greater drops and
every way and also continually change place to fill up the places forsaken by other parts of the Air which else would be empty there being no Vacuum to retire unto So that there would be a perpetual stream of Air and in a contrary way to the Motion of the Suns Body such as is the Motion of Water by the sides of a Ship under sail A. But this Motion of the Earth from West to East is onely Circular such as is described by a Compass about a Centre and cannot therefore repel the Air as the Sun does And the Disciples of Copernicus will have it to be the Cause of the Moons monthly motion about the Earth B. And I think Copernicus himself would have said the same if his purpose had been to have shewn the Natural Causes of the Motions of the Stars But that was no part of his designe which was onely from his own observations and those of former Astronomers to compute the times of their Motions partly to foretel the Conjunctions Oppositions and other Aspects of the Planets and partly to regulate the times of the Churches Festivals But his followers Kepler and Galileo make the Earths Motion to be the Efficient Cause of the Monthly motion of the Moon about the Earth which without the like Motion to that of the Sun in LM is impossible Let us therefore for the present take it in as a necessary Hypothesis which from some Experiment that I shall produce in our following discourses may prove to be a certain truth A. But seeing A is the Centre both of the Suns Body and of the Annual Motion of the Earth How can it be as all Astronomers say it is that the Orb of the Annual Motion of the Earth should be Excentrique to the Suns Body For you know that from the Vernal Aequinox to the Autumnal there be 187 days but from the Autumnal Aequinox to the Vernal there be but 178 days What Natural Cause can you assigne for this Excentricity B. Kepler ascribes it to a Magnetique vertue viz. that one part of the Earths Superficies has a greater kindness for the Sun than the other part A. I am not satisfied with that It is Magical rather than Natural and unworthy of Kepler Tell me your own opinion of it B. I think that the Magnetical vertue he speaks of consisteth in this that the Southern Hemisphere of the Earth is for the greatest part Sea and that the greatest part of the Northern Hemisphere is dry Land But how it is possible that from thence should proceed the Excentricity the Sun being neerest to the Earth when he is in the Winter-Solstice I shall shew you when we come to speak of the Motions of Air and Water A. That 's time enough For I intend it for our next meeting In the mean time I pray you tell me what you think to be the Cause why the Equinoctial and consequently the Solstitial points are not always in one and the same point of the Ecliptique of the Fixt Stars I know they are not because the Sun does not rise and set in points diametrally opposite For if it did there would be no difference of the Seasons of the year B. The cause of that can be no other than that the Earth which is l m hath the like Motion to that which I suppose the Sun to have in L M compounded of streight and circular from West to East in a day as the Annual Motion hath in a year so that not reckoning the Excentricity it will be moved through the Ecliptiques one Revolution as Copernicus proveth about one degree Suppose then the whole Earth moved from H to I which is half the year circularly but falling from I to i in the same time about 30 minutes and as much in the other Hemisphere from H to k then draw the line i k which will be equal and parallel to H I and be the Diameter of the Aequator for the next year But it shall not cut the Diameter of the Ecliptick B Z in A which was the Equinoctial of the former year but in o 36 seconds from the first degree of Aries Suppose the same done in the Hemisphere under the Plain of the paper and so you have the double of 36 seconds that is 72 seconds or very neer for the progress of the Vernal Equinox in a year The cause why I suppose the Arch I i to be half a degree in the Ecliptique of the Earth is that Copernicus and other Astronomers and Experience agree in this that the Aequinoctial points proceed according to the order of the Signes Aries Taurus Gemini c. from West to East every 100 year one degree or very neer A. In what time do they make the whole Revolution through the Ecliptique of the Sky B. That you may reckon For we know by Experience that it hath proceeded about one degree that is 60 minutes constantly a long time in a hundred years But as 100 years to one degree so is 36000 years to 360 degrees Also as 100 years to one degree so is one year to the hundred part of one degree or 60 minutes which is 60 100 or 36 seconds for the progress of one year which must be somewhat more than a degree according to Copernicus who lib. 3. cap. 2. saith That for 400 years before Ptolomie it was one degree almost constantly Which is well enough as to the Natural Cause of the Precession of the Aequinoctial points which is the often-said compounded Motion though not an exact Astronomical Calculation A. And 't is a great signe that his Supposition is true But what is the Cause that the Obliquity of the Ecliptique that is the distance between the Aequinoctial and the Solstice is not always the same B. The necessity of the Obliquity of the Ecliptique is but a consequence to the Precession of the Aequinoctial points And therefore if from C the North-Pole you make a little Circle C u equal to 15 minutes of a degree upon the Earth and another u s equal to the same which will appear like this Figure 8 that is as Copernicus calls it a Circle twined the Pole C will be moved half the time of the Aequinoctial points in the arc C u and as much in the alternate arc u s descending to s. But in the arc s u and its alternate rising to C. The cause of the twining is the Earths Annual Motion the same way in the Ecliptique and makes the four quarters of it and makes also their revolution twice as slow as that of the Aequinoctial points And therefore the Motion of it is the same compounded Motion which Copernicus takes for his Supposition and is the cause of the Precession of the Aequinoctial points and consequently of the variation of the Obliquity adding to it or taking from it somewhere more somewhere less so as that one with another the addition is not much more nor the substraction much less than 30 minutes But as
fall by their weight So also it is forced up in moist ground and with it many small Atomes of the Earth which are either twisted with the rising water into Plants or are carried up and down in the Air incertainly But the greatest Quantity of Water is forced up from the great South and Indian Seas that lie under the Tropique of Capricorn And this Climate is that which makes the Suns Perigaeum to be always on the Winter-Solstice And that is the part of the Terrestrial Globe which Keplerus says is kinde to the Sun whereas the other part of the Globe which is almost all dry land has an Antipathy to the Sun And so you see where this Magnetical vertue of the Earth lies For the Globe of the Earth having no Natural Appetite to any place may be drawn by this Motion of the Sun a little neerer to it together with the water which it raiseth A. Can you guess what may be the Cause of Wind B. I think it manifest that the unconstant Winds proceed from the uncertain Motion of the Clouds ascending and descending or meeting with one another For the Winds after they are generated in any place by the descent of a Cloud they drive other Clouds this way and that way before them the Air seeking to free it self from being pent up in a straight For when a Cloud descendeth it makes no wind sensible directly under it self But the Air between it and the Earth is prest and forced to move violently outward For it is a certain Experiment of Mariners that if the Sea go high when they are becalmed they say they shall have more Wind than they would and take in their Sails all but what is necessary for steering They know it seems that the Sea is moved by the descent of Clouds at some distance off Which presseth the water and makes it come to them in great Waves For a Horizontal Wind does but curl the Water A. From whence come the Rivers B. From the Rain or from the falling of Snow on the higher ground But when it descendeth under ground the place where it again ariseth is called the Spring A. How then can there be a Spring upon the top of a Hill B. There is no Spring upon the very top of a Hill unless some Natural Pipe bring it thither from a higher Hill A. Julius Scaliger says there is a River and in it a Lake upon the top of Mount Cenis in Savoy and will therefore have the Springs to be ingendred in the Caverns of the Earth by Condensation of the Air. B. I wonder he should say that I have pass'd over that Hill twice since the time I read that in Scaliger and found that River as I pass'd and went by the side of it in plain ground almost two miles Where I saw the water from two great Hills one on one side the other on the other in a thousand small Rillets of melting Snow fall down into it Which has made me never to use any Experiment the which I have not my self seen As for the conversion of Air into Water by Condensation and of Water into Air by Rarefaction though it be the doctrine of the Peripatetiques it is a thing incogitable and the words are insignificant For by Densum is signified onely frequencie and closeness of parts and by Rarum the contrary As when we say a Town is thick with houses or a Wood with trees we mean not that one house or tree is thicker than another but that the spaces between are not so great But since there is no Vacuum the spaces between the parts of Air are no larger than between the parts of Water or of any thing else A. What think you of those things which Mariners that have sailed through the Atlantick Sea called Spouts which pour down water enough at once to drown a great Ship B. 'T is a thing I have not seen And therefore can say nothing to it though I doubt not but when two very large and heavie Clouds shall be driven together by two great and contrary winds the thing is possible A. I think your reason good And now will propound to you another Experiment I have seen an exceeding small Tube of Glass with both ends open set upright in a Vessel of Water and that the Superficies of the Water within the Tube was higher a good deal than of that in the Vessel but I see no reason for it B. Was not part of the Glass under Water Must not then the Water in the Vessel rise Must not the Air that lay upon it rise with it Whither should this rising Air go since there is no place empty to receive it It is therefore no wonder if the Water press'd by the Substance of the Glass which is dipt into it do rather rise into a very small Pipe than come about a longer way into the open Air. A. 'T is very probable I observed also that the top of the inclosed Water was a concave Superficies which I never saw in other Fluids B. The Water hath some degree of tenacity though not so great but that it will yield a little to the Motion of the Air as is manifest in the Bubbles of water where the concavity is always towards the Air. And this I think the cause why the Air and Water meeting in the Tube make the Superficies towards the Air concave which it cannot do to a Fluid of greater tenacity A. If you put into a Bason of Water a long rag of Cloth first drenched in water and let the longer part of it hang out it is known by Experience that the Water will drop out as long as there is any part of the other end under Water B. The cause of it is that water as I told you hath a degree of tenacity And therefore being continued in the rag till it be lower without than within the weight will make it continue dropping though not onely because it is heavie for if the rag lay higher without than within and were made heavier by the breadth it would not descend but 't is because all heavie Bodies Naturally descend with proportion of swiftness duplicate to that of the time whereof I shall say more when we talk of Gravity A. You see how despicable Experiments I trouble you with But I hope you will pardon me B. As for mean and common Experiments I think them a great deal better Witnesses of Nature than those that are forced by fire and known but to very few CAP. VI. Of the Causes and Effects of Heat and Cold. A. 'T Is a fine day and pleasant walking through the Fields but that the Sun is a little too hot B. How know you that the Sun is hot A. I feel it B. That is to say you know that your self but not that the Sun is hot But when you finde your self hot what Body do you feel A. None B. How then can you infer your heat from the Sense of Feeling Your walking
may have made you hot Is Motion therefore hot No. You are to consider the Concomitants of your heat as that you are more faint or more ruddy or that you sweat or feel some Endeavour of Moisture or Spirits tending outward and when you have found the Causes of those Accidents you have found the Causes of Heat which in a living Creature and specially in a Man is many times the Motion of the parts within him such as happen in sickness anger and other passions of the minde which are not in the Sun nor in Fire A. That which I desire now to know is what Motions and of what Bodies without me are the Efficient Causes of my Heat B. I shewed you yesterday in discoursing of Rain how by this compounded Motion of the Suns Body the Air was every way at once thrust off West and East so that where it was contiguous the small parts of the water were forced to rise for the avoiding of Vacuum Think then that your hand were in the place of water so exposed to the Sun Must not the Sun work upon it as it did upon the Water Though it break not the skin yet it will give to the inner Fluids and looser parts of your hand an Endeavour to get forth which will extend the skin and in some climates fetch up the bloud and in time make the skin black The Fire also will do the same to them that often sit with their naked skins too neer it Nay one may sit so neer without touching it as it shall blister or break the skin and fetch up both spirits and bloud mixt into a putrid oyly matter sooner than in a Furnace Oyl can be extracted out of a Plant. A. But if the Water be above the Fire in a Kettle what then will it do Shall the particles of water go toward the Fire as it did toward the Sun B. No. For it cannot But the Motion of the parts of the Kettle which are caused by the Fire shall dissipate the Water into Vapour till it be all cast out A. What is that you call Fire Is it a hard or Fluid Body B. It is not any other Body but that of the shining coal which coal though extinguished with Water is still the same Body So also in a very hot Furnace the hollow spaces between the shining coals though they burn that you put into them are no other Body than Air moved A. Is it not Flame B. No. For flame is nothing but a multitude of Sparks and Sparks are but the Atomes of the Fewel dissipated by the incredible swift Motion of the Movent which makes every Spark to seem a hundred times greater than it is as appears by this That when a man swings in the Air a small stick fired at one end though the Motion cannot be very swift yet the Fire will appear to the eye to be a long streight or crooked Line Therefore a great many sparks together flying upward must needs appear unto the sight as one continued Flame Nor are the sparks striken out of a Flint any thing else but small particles of the stone which by their swift Motion are made to shine But that Fire is not a substance of it self is evident enough by this that the Sun-beams passing through a Globe of Water will burn as other fire does Which beams if they were indeed Fire would be quenched in the passage A. This is so evident that I wonder so wise men as Aristotle and his followers for so long a time could hold it for an Element and one of the primary parts of the Universe But the Natural heat of a man or other living Creature whence proceedeth it Is there any thing within their Bodies that hath this compounded Motion B. At the breaking up of a Deer I have seen it plainly in his Bowels as long as they were warm And it is called the Peristaltique Motion and in the Heart of a Beast newly taken out of his Body and this Motion is called Systole and Diastole But they are both of them this compounded Motion whereof the former causeth the food to Winde up and down through the guts and the later makes the Circulation of the Blood A. What kind of Motion is the Cause of Cold Methinks it should be contrary to that which causeth Heat B. So it is in some respect For seeing the Motion that begets Heat tendeth to the separation of the parts of the Body whereon it acteth it stands with reason that the Motion which maketh Cold should be such as sets them closer together But contrary Motions are to speak properly when upon two ends of a Line two Bodies move towards each other the Effect whereof is to make them meet But each of them as to this Question is the same A. Do you think as many Philosophers have held and now hold that Cold is nothing but a privation of Heat B. No. Have you never heard the Fable of the Satyre that dwelling with a Husbandman and seeing him blow his fingers to warm them and his Pottage to cool it was so scandalized that he ran from him saying he would no longer dwell with one that could blow both Hot and Cold with one breath Yet the Cause is evident enough For the Air which had gotten a Calefactive power from his vital parts was from his mouth and throat gently diffused on his fingers and retained still that power But to cool his Pottage he streightened the passage at his lips which extinguished the Calefactive Motion A. Do you think Wind the general Cause of Cold If that were true in the greatest Winds we should have the greatest Frosts B. I mean not any of those uncertain Winds which I said were made by the Clouds but such as a Body moved in the Air makes to and against it self For it is all one Motion of the Air whether it be carried against the Body or the Body against it Such a Wind as is constant if no other be stirring from East to West made by the Earth turning dayly upon its own Centre Which is so swift as except it be kept off by some hill to kill a man as by Experience hath been found by those who have passed over great Mountains and specially over the Andies which are opposed to the East And such is the Wind which the Earth maketh in the Air by her Annual Motion which is so swift as that by the Calculation of Astronomers to go Sixty miles in a minute of an hour And therefore this must be the Motion which makes it so cold about the Poles of the Ecliptique A. Does not the Earth make the Wind as great in one part of the Ecliptique as in another B. Yes But when the Sun is in Cancer it tempers the Cold and still less and less but least of all in the Winter-Solstice where his beams are most oblique to the Superficies of the Earth A. I thought the greatest Cold had been about the Poles of the
Aequator B. And so did I once But the reason commonly given for it is so improbable that I do not think so now For the Cause they render of it is onely that the Motion of the Earth is swiftest in the Aequinoctial and slowest about the Poles and consequently since Motion is the Cause of Heat and Cold is but as 't was thought a want of the same they inferr'd that the greatest Cold must be about the Poles of the Aequinoctial Wherein they miscounted For not every Motion causeth Heat but this agitation onely which we call compounded Motion though some have alleadged Experience for that opinion as that a Bullet out of a Gun will with its own swiftness melt Which I never shall believe A. 'T is a common thing with many Philosophers to maintain their Fancies with any rash report and sometimes with a Lye But how is it possible that so soft a Substance as water should be turned into so hard a Substance as Ice B. When the Air shaves the Globe of the Earth with such swiftness as that of Sixty miles in a minute of an hour it cannot where it meets with still water but beat it up into small and undistinguishable bubbles and involve it self in them as in so many bladders or skins of Water And Ice is nothing else but the smallest imaginable parts of Air and Water mixt which is made hard by this compounded Motion that keeps the parts so close together as not to be separated in one place without disordering the Motion of them all For when a Body will not easily yield to the impression of an external Movent in one place without yielding in all we call it Hard And when it does we say 't is Soft A. Why is not Ice as well made in a moved as in a still water Are there not great Seas of Ice in the Northern parts of the Earth B. Yes and perhaps also in the Southern parts But I cannot imagine how Ice can be made in such agitation as is always in the open Sea made by the Tides and by the Winds But how it may be made at the Shoar it is not hard to imagine For in a River or Current though swift the water that adhereth to the banks is quiet and easily by the Motion of the Air driven into small insensible bubbles and so may the water that adhereth to those bubbles and so forwards till it come into a stream that breaks it and then it is no wonder though the fragments be driven into the open Sea and freeze together into greater lumps But when in the open Sea or at the Shoar the Tide or a great Wave shall arise this young and tender Ice will presently be washt away And therefore I think it evident that as in the Thames the Ice is first made at the banks where the Tide is weak or none and broken by the stream comes down to London and part goes to the Sea floating till it dissolve and part being too great to pass the Bridge stoppeth there and sustains that which follows till the River be quite frozen over So also the Ice in the Northern Seas begins first at the banks of the Continent and Islands which are scituated in that Climate and then broken off are carried up and down and one against another till they become great Bodies A. But what if there be Islands and narrow Inlets of the Sea or Rivers also about the Pole of the Aequinoctial B. If there be 't is very likely the Sea may also there be covered all over with Ice But for the truth of this we must stay for some further discovery A. When the Ice is once made and hard what dissolves it B. The Principal Cause of it is the weight of the water it self but not without some abatement in the Stream of the Air that hardned it as when the Sun-beams are less oblique to the Earth or some contrary Wind resisteth the stream of the Air. For when the impediment is removed then the nature of the water only worketh and being a heavie Body downward A. I forgot to ask you Why two pieces of Wood rub'd swiftly one against another will at length set on fire B. Not onely at length but quickly if the Wood be dry And the Cause is evident viz. the compounded Motion which dissipates the external small parts of the Wood. And then the inner parts must of necessity to preserve the Plenitude of the Universe come after first the most Fluid and then those also of greater consistence which are first erected and the Motion continued made to flie swiftly out whereby the Air driven to the Eye of the beholder maketh that fancie which is called Light A. Yes I remember you told me before that upon any strong pressure of the Eye the resistance from within would appear a Light But to return to the enquiry of Heat and Cold there be two things that beyond all other put me into admiration One is the swiftness of kindling in Gunpowder The other is the freezing of Water in a Vessel though not far from the fire set about with other water with Ice and Snow in it When Paper or Flax is flaming the flame creeps gently on and if a house full of Paper were to be burnt with putting a Candle to it it will be long in burning whereas a spark of fire would set on flame a mountain of Gunpowder in almost an instant B. Know you not Gunpowder is made of the powder of Charcole Brimstone and Salt-peter Whereof the first will kindle with a spark the second flame as soon as toucht with fire and the third blows it as being composed of many Orbs of Salt fill'd with Air and as it dissolveth in the flame furiously blowing increaseth it And as for making Ice by the fire side It is manifest that whilst the Snow is dissolving in the external vessel the Air must in the like manner break forth and shave the Superficies of the inner vessel and work through the water till it be frozen A. I could easily assent to this if I could conceive how the Air that shaves as you say the outside of the Vessel could work through it I conceive well enough a pail of water with Ice or Snow dissolving in it and how it causeth Wind. But how that Wind should communicate it self through the vessel of wood or metal so as to make it shave the Superficies of the water which is within it I do not so well understand B. I do not say the inner Superficies of the vessel shaves the water within it But 't is manifest that the Wind made in the Pail of water by the melting Snow or Ice presseth the sides of the Vessel that standeth in it and that the pressure worketh clean through how hard soever the Vessel be and that again worketh on the water within by restitution of its parts and so hardeneth the water by degrees A. I understand you now The Ice in the Pail
Motion of the Earth For whatsoever having been asunder comes together again must come contrary ways as those that follow one another go the same way though both move upon the same Line A. What Experiment have you seen to this purpose B. I have seen a drop of glass like that of the second Figure newly taken out of the furnace and hanging at the end of an Iron rod and yet Fluid and let fall into the water and hardned The Club-end of it A A coming first to the water the tail B C following it 'T is proved before that the motion that makes it is a compounded Motion and gives an Endeavour outward to every part of it and that the Motion which maketh Cold is such as shaving the Body in every point of contact and turning it gives them all an Endeavour inward Such is this Motion made by the sinking of the hot and fluid glass into the water 'T is therefore manifest that the Motion which hardneth a Soft Body must in every point of contact be in the contrary way to that which makes a hard body Soft And further that slender tail B C shall be made much more hard than common Glass For towards the upper end in C you cannot easily break it as small as it is And when you have broken it the whole Body will fall into dust as it must do seeing the bending is so difficult For all the parts are bent with such force that upon the breaking at D by their sudden restitution to their liberty they will break together And the cause why the tail B C being so slender becomes so hard is that all the Endeavour in the great part A B is propagated to the small part B C in the same manner as the force of the Sun-beams is derived almost to a point by a Burning-glass But the Cause why when it is broken in D it breaks also in so many other places is that the Endeavour in all the other parts which is called the Spring unbends it from whence a Motion is caused the contrary way and that Motion continued bends it more the other way and breaks it as a Bow over-bent is broken into shivers by a sudden breaking of the string A. I conceive now how a Body which having been Hard and softned again may be re-hardned but how a Fluid and meer Homogeneous Body as Air or Water may be so I see not yet For the hardning of water is making a hard Body of two Fluids whereof one which is the water hath some tenacity and so a man may make a Bladder hard with blowing into it B. As for meer Air which hath no Natural Motion of it self but is moved onely by other Bodies of a greater consistence I think it impossible to be hardned For the parts of it so easily change places that they can never be fixt by any Motion No more I think can Water which though somewhat less Fluid is with an insensible force very easily broken A. It is the opinion of many learned men that Ice in long time will be turned into Christal and they alleadge Experience for it For they say that Christal is found hanging on high Rocks in the Alps like Isicles on the Eaves of a house and why may not that have formerly been Ice and in many years have lost the power of being reduced B. If that were so it would still be Ice though also Christal Which cannot be because Christal is heavier than Water and therefore much heavier than Ice A. Is there then no transubstantiation of Bodies but by mixture B. Mixture is no transubstantiation A. Have you never seen a Stone that seemed to have been formerly Wood and some like Shells and some like Serpents and others like other things B. Yes I have seen such things and particularly I saw at Rome in a Stone-cutters work-house a Billet of Wood as I thought it partly covered with bark and partly with the grain bare as long as a mans Arm and as thick as the Calf of a mans Leg which handling I found extreme heavie and saw a small part of it which was polished and had a very fine Gloss and thought it a substance between Stone and Metal but neerest to Stone I have seen also a kind of Slate painted naturally with Forest-work And I have seen in the hands of a Chymist of my acquaintance at Paris a broken Glass part of a Retort in which had been the Rozin of Turpentine wherein though there were left no Rozin yet there appeared in the piece of Glass many Trees and Plants in the ground about them such as grow in Woods and better designed than they could be done by any Painter and continued so for a long time These be great wonders of Nature but I will not undertake to shew their causes But yet this is most certain that nothing can make a hard Body of a Soft but by some Motion of its parts For the parts of the Hardest Body in the world can be no closer together than to touch and so close are the parts of Air and Water and consequently they should be equally Hard if their smallest parts had not different Natural Motions Therefore if you ask me the Causes of these Effects I answer They are different Motions But if you expect from me how and by what Motions I shall fail you For there is no kind of Substance in the World now that was not at the first Creation when the Creator gave to all things what Natural and special Motion he thought good And as he made some Bodies wondrous great so he made others wondrous little For all his works are wondrous Man can but guess nor guess further than he hath knowledge of the variety of Motion I am therefore of opinion that whatsoever perfectly Homogeneous is Hard consisteth of the smallest parts or as some call them Atomes that were made Hard in the beginning and consequently by an Eternal Cause and that the hardness of the whole Body is caused onely by the contact of the parts by pressure A. What Motion is it that maketh a hard Body to melt B. The same compounded Motion that heats namely that of Fire if it be strong enough For all Motion compounded is an Endeavour to dissipate as I have said before the parts of the Body to be moved by it If therefore hardness consist onely in the pressing Contact of the least parts this Motion will make the same parts slide off from one another and the whole to take such a figure as the weight of the parts shall dispose them to as in Lead Iron Gold and other things melted with Heat But if the small parts have such figures as they cannot exactly touch but must leave spaces between them filled with Air or other Fluids then this Motion of the fire will dissipate those parts some one way some another the Hard part still hard as in the burning of Wood or Stone into Ashes or Lime For this Motion
ask concerning Gravity If Gravity be as some define it an intrinsecal quality whereby a Body descendeth towards the Center of the Earth how is it possible that a piece of Iron that hath this intrinsecal quality should rise from the Earth to go to a Loadstone Hath it also an intrinsecal quality to go from the Earth It cannot be The Cause therefore must be extrinsecal And because when they are come together in the Air if you leave them to their own nature they will fall down together they must also have some like extrinsecal Cause And so this magnetique vertue will be such another vertue as makes all other heavy Bodies to descend in this our World to the Earth If therefore you can from this your Hypothesis of compounded Motion by which you have so probably salved the Problem of Gravity salve also this of the Loadstone I shall acknowledge both your Hypothesis to be true and your Conclusion to be well deduced B. I think it not impossible But I will proceed no further in it now than for the facilitating of the demonstrations to tell you the several proprieties of the Magnet whereof I am to shew the causes As first That Iron and no other Body at some little distance though heavy will rise to it Secondly That if it be laid upon a still Water in a floating Vessel and left to it self it will turn it self till it lye in a Meridian that is to say with one and the same Line still North and South Thirdly If you take a long slender piece of Iron and apply the Loadstone to it and according to the position of the Poles of the Loadstone draw it over to the end of the Iron the Iron will have the same Poles with the Magnet so it be drawn with some pressure but the Poles will lye in a contrary Position and also this long Iron will draw other Iron to it as the Magnet doth Fourthly This long Iron if it be so small as that poiz'd upon a Pin the weight of it have no visible Effect the Navigators use it for the Needle of their Compass because it points North and South saving that in most places by particular accidents it is diverted which diversion is called the variation of the Horizontal Needle Fifthly The same Needle placed in a Plain perpendicular to the Horizon hath another Motion called the Inclination Which that you may the better conceive draw a fourth Figure wherein let there be a Circle to represent the Terrella that is to say a Spherical Magnet A. Let this be it whose Center is A the North Pole B the South Pole C. B. Join B C and cross it at right Angles with the Diameter D E. A. 'T is done B. Upon the point D set the Needle parallel to B C with the cross for the South Pole and the Barb for the North and describe a Square about the Circle B D C E and divide the arch D B into four equal parts in a b c. A. 'T is done B. Then place the middle of the Needle on the points a b c so that they may freely turn and set the Barb which is at D toward the North and that which is at C towards the South You see plainly by this that the Angles of Inclination through the Arch D C taken all together are double to a Right Angle For when the South point of the Needle looking North as at D comes to look South as at C it must make half a Circle A. That is true And if you draw the Sine of the Arch D a which is d a and the Sine of the Arch B a which is a c and the Sine of the Arch D b which is b f and the Sine of the Arch B c which is c g the Needle will lye upon b f with the North-point downwards so that the Needle will be parallel to A D. Then from a draw the line a h making the Angle e a h equal to the Angle D A a. And then the Needle at a shall lye in the line a h with the South point toward h. Finally draw the line c h which with c g will also make a quarter of a right Angle and therefore if the Needle be plac'd on the point c it will lye in c h with the South point toward h. And thus you see by what degrees the Needle inclines or dips under the Horizon more and more from D till it come to the North Pole at B where it will lye parallel to the Needle in D but with their Barbs looking contrary ways And this is certain by experience and by none contradicted B. You see then why the degrees of the Inclinatory Needle in coming from D to B are double to the degrees of a Quadrant It is found also by experience that Iron both of the Mine and of the Furnace put into a Vessel so as to float will lay it self if some accident in the Earth hinder it not exactly North and South And now I am from this compounded Motion supposed by Copernicus to derive the causes why a Loadstone draws Iron why it makes Iron to do the same why naturally it placeth it self in a parallel to the Axis of the Earth why by passing it over the Needle it changes its Poles and what is the cause that it inclines But it is your part to remember what I told you of Motion at our second meeting and what I told you of this compounded Motion supposed by Copernicus at our fourth meeting CAP. IX Of the Loadstone and its Poles and whether they shew the Longitude of places on the Earth A. I Come now to hear what Natural Causes you can assign of the vertues of the Magnet and first why it draws Iron to it and only Iron B. You know I have no other cause to assign but some local Motion and that I never approved of any argument drawn from Sympathy Influence Substantial Forms or Incorporeal Effluvia For I am not nor am accounted by my Antagonists for a Witch But to answer this Question I should describe the Globe of the Earth greater than it is at B in the first Figure but that the Terrella in the fourth Figure will serve our turn For 't is but calling B and C the Poles of the Earth and D E the Diameter of the Aequinoctial Circle and making D the East and E the West And then you must remember that the Annual Motion of the Earth is from West to East and compounded of a straight and circular Motion so as that every point of it shall describe a small Circle from West to East as is done by the whole Globe And let the Circles about a b c be three of those small Circles A. Before you go any further I pray you shew me how I must distinguish East and West in every part of this Figure For wheresoever I am on Earth suppose at London and see the Sun rise suppose in Cancer is not a