conversion of the Earth by which conversion all things that adhere to its superficies are necessarily carried about with it may be referred the three Phaenomena concerning the Tides of the Ocean Whereof the first is the alternate elevation and depression of the Water at the Shores twice in the space of 24 houres and neer upon 52 minutes for so it has constantly continued in all ages The second that at the New and Full Moons the elevations of the Water are greater then at other times between And the third that when the Sunne is in the Equinoctial they are yet greater then at any other time For the salving of which Phaenomena we have already the foure above-mentioned Motions to which I assume also this that the part of the Earth which is called America being higher then the Water and extended almost the space of a whole Semicircle from North to South gives a stop to the motion of the Water This being granted In the same 4th figure where l b k c is supposed to be in the plain of the Moons monethly motion let the little Circle l d k e be described about the same Center a in the plain of the Equinoctial This Circle therefore will decline from the Circle l b k c in an angle of almost 28 degrees and ½ for the greatest declination of the Ecliptick is 23½ to which adding 5 for the greatest declination of the Moon from the Ecliptick the summe wil be 28 degrees and ½ Seeing now the Waters which are under the Circle of the Moons course are by reason of the Earths Simple Motion in the plain of the same Circle moved together with the Earth that is to say together with their own bottoms neither out-going nor out-gone if we add the Diurnal motion by which the other Waters which are under the Equinoctial are moved in the same order and consider withall that the Circles of the Moon and of the Equinoctial intersect one another it will be manifest that both those Waters which are under the Circle of the Moon and under the Equinoctiall will runne together under the Equinoctial and consequently that their Motion will not onely be swifter then the ground that carries them but also that the waters themselves will have greater elevation whensoever the Earth is in the Equinoctial Wherefore whatsoever the cause of the Tides may be this may be the cause of their augmentation at that time Againe seeing I have supposed the Moon to be carried about by the simple motion of the Earth in the little circle lbkc and demonstrated at the 4 article of the 21 chapter that whatsoever is moved by a Movent that hath simple motion will be moved allwayes with the same velocity it follows that the center of the Earth will be carried in the circumference lbkc with the same velocity with which the Moon is carried in the circumference mnop Wherefore the time in which the Moon is carried about in mnop is to the time in which the Earth is carried about in lbkc as one circumference to the other that is as ao to ak But ao is observed to be to the Semidiameter of the Earth as 59 to 1 and therefore the Earth if ak be put for its Semidiameter will make 59 revolutions in lbkc in the time that the Moon makes one monthly circuit in mnop But the Moon makes her monthly circuit in little more then 29 dayes Wherefore the Earth shal make its circuit in the circumference lbkc in 12 hours and a little more namely about 26 minutes more that is to say it shall make two circuits in 24 hours and allmost 52 minutes which is observed to be the time between the high water of one day and the high water of the day following Now the course of the waters being hindered by the southern part of America their motion will be interrupted there and consequently they will be elevated in those places and sink down again by their own waight twice in the space of 24 hours and 52 minutes And thus I have given a possible cause of the diurnall reciprocation of the Ocean Now from this swelling of the Ocean in those parts of the Earth proceed the Flowings and Ebbings in the Atlantick Spanish Brittish and German Seas which though they have their set times yet upon severall Shores they happen at severall hours of the day and they receive some augmentation from the North by reason that the shores of China and Tartaria hindering the generall course of the waters makes them swell there and discharge themselves in part through the straight of Anian into the Northern Ocean and so into the German Sea As for the Spring Tides which happen at the time of the New Full Moons they are caused by that simple motion which at the beginning I supposed to be allwayes in the Moone For as when I shewed the cause of the Excentricity of the Earth I derived the elevation of the waters from the simple motion of the Sunne so the same may here be derived from the simple motion of the Moon For though from the generation of Clouds there appeare in the Sunne a more manifest power of elevating the waters then in the Moon yet the power of encreasing moisture in Vegetables and living creatures appears more manifestly in the Moon then in the Sunne which may perhaps proceed from this that the Sunne raiseth up greater and the Moon lesser drops of water Neverthelesse it is more likely and more agreeable to common observation that Raine is raised not only by the Sunne but also by the Moon for allmost all men expect change of weather at the time of the Conjunctions of the Sunne and Moon with one another and with the Earth more then in the time of their Quarters In the last place the cause why the Spring Tides are greater at the time of the Aequinoxes hath been already sufficiently declared in this Article where I have demonstrated that the two Motions of the Earth namely its Simple Motion in the little Circle lbkc and its Diurnal motion in ldke cause necessarily a greater elevation of Waters when the Sunne is about the Aequinoxes then when he is in other places I have therefore given possible causes of the Phaenomenon of the Flowing and Ebbing of the Ocean 11 As for the explication of the yearly Praecession of the Aequinoctial points we must remember that as I have already shewn the annual motion of the Earth is not in the Circumference of a Circle but of an Ellipsis or a line not considerably different from that of an Ellipsis In the first place therefore this Elliptical line is to be described Let the Ecliptick ♎ ♑ ♈ ♋ in the 5th figure be divided into four equal parts by the two straight lines ab and ♑ ♋ cutting one another at right angles in the Center c and taking the Arch bd of 2 degrees and 16 minutes let the straight line de be drawn parallel to ab and cutting ♑ ♋ in f
the Names of the parts of any Speech be explicated is it not necessary that the Definition should be a Name Compounded of them For example when these Names Aequilaterall Quadrilaterall Right-angled are sufficiently understood it is not necessary in Geometry that there should be at all such a Name as Square for defined Names are received in Philosophy for brevities sake onely Fiftly That Compounded Names which are defined one way in some one part of Philosophy may in another part of the same be otherwise defined as a Parabola and an Hyperbole have one Definition in Geometry and another in Rhetorique for Definitions are instituted and serve for the understanding of the Doctrine which is treated of And therefore as in one part of Philosophy a Definition may have in it some one fit Name for the more briefe explanation of some proposition in Geometry so it may have the same liberty in other parts of Philosophy for the use of Names is particular even where many agree to the setling of them and arbitrary Sixtly That no Name can be defined by any one Word because no one Word is sufficient for the Resolving of one or more words Seventhly That a defined Name ought not to be repeated in the Definition For a defined Name is the whole Compound and a Definition is the Resolution of that Compound into parts but no Totall can be part of it selfe 16 Any two Definitions that may be compounded into a Syllogisme produce a Conclusion which because it is derived from Principles that is from Definitions is said to be Demonstrated and the Derivation or Composition it selfe is called a Demonstration In like manner if a Syllogisme be made of two Propositions whereof one is a Definition the other a Demonstrated Conclusion or neither of them is a Definition but both formerly demonstrated that Syllogisme is also called a Demonstration and so successively The Definition therefore of a Demonstration is this A DEMONSTRATION is a Syllogism or Series of Syllogisms derived and continued from the Definitions of Names to the last Conclusion And from hence it may be understood that all true Ratiocination which taketh its beginning from true Principles produceth Science and is true Demonstration For as for the Originall of the Name although that which the Greeks called 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 and the Latines Demonstratio was understood by them for that sort onely of Ratiocination in which by the describing of certaine Lines and Figures they placed the thing they were to prove as it were before mens Eyes which is properly 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 or to shew by the Figure yet they seem to have done it for this reason that unlesse it were in Geometry in which only there is place for such Figures there was no Ratiocination certaine and ending in Science their Doctrines concerning all other things being nothing but Controversie and Clamour which neverthelesse hapned not because the Truth to which they pretended could not be made evident without Figures but because they wanted true Principles from which they might derive their Ratiocination and therefore there is no reason but that if true Definitions were praemised in all sorts of Doctrines the Demonstrations also would be true 17 It is proper to Methodical Demonstration First That there be a true Succession of one Reason to another according to the Rules of Syllogizing delivered above Secondly That the Praemisses of all Syllogismes be demonstrated from the first Definitions Thirdly That after Definitions he that Teaches or Demonstrates any thing proceed in the same Method by which he found it out namely that in the first place those things be demonstrated which immediately succeed to Universal Definitions in which is contained that part of Philosophy which is called Philosophia Prima Next those things which may be demonstrated by Simple Motion in which Geometry consists After Geome try such things as may be taught or shewed by manifest Action that is by Thrusting from or Pulling towards And after these the Motion or Mutation of the invisible parts of Things and the Doctrine of Sense Imagination of the internal Passions especially those of Men in which are comprehended the Grounds of Civil Duties or Civil Philosophy which takes up the last place And that this Method ought to be kept in all sorts of Philosophy is evident from hence that such things as I have said are to be taught last cannot be demonstrated till such as are propounded to be first treated of be fully understood Of which Method no other Example can be given but that Treatise of the Elements of Philosophy which I shall begin in the next Chapter and continue to the end of the worke 18 Besides those Paralogismes whose fault lies either in the Falsity of the Praemisses or the want of true Composition of which I have spoken in the praecedent Chapter there are two more which are frequent in Demonstration one whereof is commonly called Petitio Principii the other is the supposing of a False Cause and these do not onely deceive Unskilfull Learners but sometimes Masters themselves by making them take that for well demonstrated which is not demonstrated at all Petitio Principii is when the Conclusion to be proved is disguised in other Words and put for the Definition or Principle from whence it is to be demonstrated and thus by putting for the Cause of the Thing sought either the Thing it selfe or some Effect of it they make a Circle in their Demonstration As for example He that would Demonstrate that the Earth stands still in the Center of the World and should suppose the Earths Gravity to be the Cause thereof and define Gravity to be a quality by which every heavy Body tends towards the Center of the World would lose his labour for the question is What is the Cause of that quality in the Earth and therefore he that supposes Gravity to be the Cause puts the Thing it selfe for its own Cause Of a False Cause I find this example in a certaine Treatise where the thing to be demonstrated is the Motion of the Earth He begins therefore with this that seeing the Earth and the Sun are not alwayes in the same scituation it must needs be that one of them be locally moved which is true next he affirms that the Vapours which the Sun raises from the Earth and Sea are by reason of this Motion necessarily moved which also is true from whence he infers the Winds are made and this may passe for granted and by these Winds he sayes the Waters of the Sea are moved and by their Motion the bottome of the Sea as if it were beaten forwards moves round and let this also be granted wherefore he concludes the Earth is moved which is neverthelesse is a Paralogisme For if that wind were the Cause why the Earth was from the beginning moved round and the Motion either of the Sunne or the Earth were the Cause of that Wind then the Motion of the Sunne or
But in the mean time the hard particles which are mingled with the Aire and are agitated as I have supposed with Simple Motion wil not pass through the water of the clouds but be more straightly compressed within their cavities And this I have demonstrated at the 4th and 5th Articles of the 22th Chapter Besides seeing the Globe of the Earth floateth in the Aire which is agitated by the Sunnes Motion the parts of the Aire resisted by the Earth will spread themselves every way upon the Earths Superficies as I have shewn at the 8th Article of the 21th Chapter 5 We perceive a Body to be Hard from this that when touching it we would thrust forwards that part of the same which we touch we cannot do it otherwise then by thrusting forwards the whole Body We may indeed easily and sensibly thrust forwards any particle of the Aire or Water which we touch whilst yet the rest of its parts remain to sense unmoved But we cannot do so to any part of a stone Wherfore I define a Hard Body to be that whereof no part can be sensibly moved unless the whole be moved Whatsoever therefore is Soft or Fluid the same can never be made Hard but by such motion as makes many of the parts together stop the motion of some one part by resisting the same 6 These things premised I shall shew a possible cause why there is greater Cold neer the Poles of the Earth then further from them The motion of the Sunne between the Tropicks driving the Aire towards that part of the Earths Superficies which is perpendicularly under it makes it spread it self every way and the velocity of this expansion of the Aire grows greater and greater as the Superficies of the Earth comes to be more and more straightned that is to say as the Circles which are parallel to the Aequator come to be less and less Wherefore this expansive motion of the Aire drives before it the parts of the Aire which are in its way continually towards the Poles more and more strongly as its force comes to be more and more united that is to say as the Circles which are parallel to the Aequator are less and less that is so much the more by how much they are neerer to the Poles of the Earth In those places therefore which are neerer to the Poles there is greater Cold then in those which are more remote from them Now this expansion of the Aire upon the Superficies of the Earth from East to West doth by reason of the Sunnes perpetual accession to the places which are successively under it make it Cold at the time of the Sunnes Rising and Setting but as the Sunne comes to be continually more and more perpendicular to those cooled places so by the Heat which is generated by the supervening Simple Motion of the Sunn that Cold is again remitted and can never be great because the action by the which it was generated is not permanent Wherefore I have rendred a possible cause of Cold in those places that are neer the Poles or where the obliquity of the Sunne is great 7 How Water may be congeled by Cold may be explained in this manner Let A in the first figure represent the Sunne and B the Earth A will therefore be much greater then B. Let EF be in the plain of the Equinoctial to which let GH IK and LC be parallel Lastly let C and D be the Poles of the Earth The Aire therefore by its action in those parallels will rake the Superficies of the Earth and that with motion so much the stronger by how much the parallel Circles towards the Poles grow less and less From whence must arise a Wind which will force together the uppermost parts of the water and withal raise them a little weakning their endeavour towards the Center of the Earth And from their endeavour towards the center of the Earth joyned with the endeavour of the said Wind the uppermost parts of the water will be pressed together and coagulated that is to say the top of the water will be skinned over and hardned And so againe the Water next the top will be hardned in the same manner till at length the Ice be thick And this Ice being now compacted of little hard Bodies must also containe many particles of ayre received into it As Rivers and Seas so also in the same manner may the Clouds be frozen For when by the ascending and descending of severall Clouds at the same time the Air intercepted between them is by compression forced out it rakes by little little hardens them And though those smal drops which usually make Clouds be not yet united into greater Bodies yet the same Wind will be made by it as water is congeled into Ice so will Vapours in the same manner be congeled into Snow From the same cause it is that Ice may be made by art and that not farre from the fire For it is done by the mingling of Snow and Salt together and by burying in it a small vessell full of Water Now while the Snow and Salt which have in them a great deale of aire are melting the aire which is pressed out every way in Wind rakes the sides of the Vessel and as the Wind by its motion rakes the Vessell so the Vessell by the same motion and action congeles the Water within it We find by experience that Cold is allwayes more Remisse in places where it raynes or where the weather is cloudy things being alike in all other respects then where the aire is cleare And this agreeth very well with what I have sayd before For in cleare weather the course of the Wind which as I sayd even now rakes the Superficies of the Earth as it is free from all interruption so also it is very strong But when small drops of water are either rising or falling that Wind is repelled broken and dissipated by them and the lesse the Wind is the lesse is the Cold. We find also by experience that in deep Wells the Water freezeth not so much as it doth upon the Superficies of the Earth For the Wind by which Ice is made entring into the Earth by reason of the laxity of its parts more or lesse loseth some of its force though not much So that if the Well be not deep it will freeze whereas if it be so deep as that the Wind which causeth cold cannot reach it it will not freeze We find moreover by experience that Ice is lighter then Water The cause whereof is manifest from that which I have already shewn namely that Aire is received in and mingled with the particles of the Water whilest it is in congeling 8 We have seen one way of making things Hard namely by Congelation Another way is thus Having already supposed that innumerable Atomes some harder then others and that have several simple motions of their own are intermingled with the aethereal substance
not a sufficient cause of their future Motion there being no other cause of Motion but Motion The cause therefore of such Restitution is in the parts of the Steel it self Wherefore whilest it remains bent there is in the parts of which it consisteth some motion though invisible that is to say some endeavour at least that way by which the restitution is to be made and therefore this endeavour of all the parts together is the first beginning of Restitution so that the impediment being removed that is to say the force by which it was held bent it will be restored again Now the motion of the parts by which this is done is that which I called Simple Motion or Motion returning into it self When therefore in the bending of a plate the ends are drawn together there is on one side a mutual compression of the parts which compression is one endeavour opposite to another endeavour and on the other side a divulsion of the parts The endeavour therefore of the parts on one side tends to the restitution of the plate from the middle towards the ends and on the other side from the ends towards the middle Wherefore the impediment being taken away this endeavour which is the beginning of restitution will restore the plate to its former posture And thus I have given a possible cause why some Bodies when they are bent Restore themselves again which was to be done As for Stones seeing they are made by the accretion of many very hard particles within the Earth which particles have no great coherence that is to say touch one another in small latitude and consequently admit many particles of aire it must needs be that in bending of them their internal parts will not easily be compressed by reason of their hardness And because their coherence is not firm as soon as the external hard particles are disjoyned the aethereal parts will necessarily break out and so the Body will suddenly be broken 13 Those Bodies are called Diaphanous upon which whilest the Beams of a lucid Body do work the action of every one of those Beams is propagated in them in such manner as that they still retain the same order amongst themselves or the inversion of that order and therefore Bodies which are perfectly Diaphanous are also perfectly homogeneous On the contrary an Opacous Body is that which by reason of its heterogeneous nature doth by innumerable reflexions and refractions in particles of different figures and unequal hardness weaken the Beams that fall upon it before they reach the Eie And of Diaphanous Bodies some are made such by Nature from the beginning as the substance of the Aire and of the Water and perhaps also some parts of Stones unless these also be Water that has been long congeled Others are made so by the power of Heat which congregates homogeneons Bodies But such as are made Diaphanous in this manner consist of parts which were formerly Diaphanous 14 In what manner Clouds are made by the motion of the Sunne elevating the particles of Water from the Sea and other moist places hath been explained in the 26th Chapter Also how Clouds come to be frozen hath been shewn above at the 7th Article Now from this that Aire may be enclosed as it were in Caverns and pent together more and more by the meeting of ascending and descending Clouds may be deduced a possible Cause of Thunder and Lightening For seeing the Aire consists of two parts the one Aethereal which has no proper motion of its own as being a thing divisible into the least parts the other Hard namely consisting of many hard Atomes which have every one of them a very swift simple motion of its own whilest the Clouds by their meeting do more and more straighten such Cavities as they intercept the Aethereal parts will penetrate and pass through their watry substance but the hard parts will in the mean time be the more thrust together and press one another and consequently by reason of their vehement motions they will have an endeavour to rebound from each other Whensoever therefore the compression is great enough and the concave parts of the Clouds are for the cause I have already given congeled into Ice the Cloud wil necessarily be broken this breaking of the Cloud produceth the first clap of Thunder Afterwards the Aire which was pent in having now broken through makes a concussion of the Aire without and from hence proceeds the roaring and murmur which follows and both the first Clap and the Murmur that follows it make that noise which is called Thunder Also from the same Aire breaking through the Clouds and with concussion falling upon the Eie proceeds that action upon our Eie which causeth in us a perception of that Light which we call Lightening Wherefore I have given a possible cause of Thunder and Lightening 15 But if the Vapours which are raised into Clouds do run together again into Water or be congeled into Ice from whence is it seeing both Ice and Water are heavy that they are sustained in the Aire Or rather what may the cause be that being once elevated they fall down again For there is no doubt but the same force which could carry up that Water could also sustain it there Why therefore being once carried up doth it fall again I say it proceeds from the same Simple Motion of the Sunne both that Vapours are forced to ascend and that Water gathered into Clouds is forced to descend For in the 21th Chapter and 11th Article I have shewn how Vapours are elevated and in the same Chapter and 5th Article I have also shewn how by the same motion Homogeneous Bodies are congregated Heterogeneous dissipated that is to say how such things as have a like nature to that of the Earth are driven towards the Earth that is to say what is the cause of the descent of Heavy Bodies Now if the action of the Sun be hindered in the raising of vapours and be not at all hindered in the casting of them down the Water will descend But a Cloud cannot hinder the action of the Sunne in making things of an earthly nature descend to the Earth though it may hinder it in making Vapours ascend For the lower part of a thick Cloud is so covered by its upper part as that it cannot receive that action of the Sunne by which Vapours are carried up because Vapours are raised by the perpetual fermentation of the Aire or by the separating of its smallest parts from one another which is much weaker when a thick Cloud is interposed then when the Skie is cleere And therefore whensoever a Cloud is made thick enough the water which would not descend before will then descend unless it be kept up by the agitation of the Winde Wherefore I have rendred a possible cause both why the Clouds may be sustained in the Aire and also why they may fall down again to the Earth which was propounded to
times of their descents cannot be easily measured with sufficient exactness and also because the places neer the Poles are inaccessible Nevertheless this we know that by how much the neerer we come to the Poles by so much the greater are the Flakes of the Snow that falls and by how much the more swiftly such Bodies descend as are fluid and dissipable by so much the smaller are the particles into which they are dissipated 5 Supposing therefore this to be the cause of the Descent of Heavy Bodies it will follow that their motion will be accelerated in such manner as that the spaces which are transmitted by them in the several times will have to one another the same proportion which the odd numbers have in succession from Unity For if the straight line EA be divided into any number of equal parts the Heavy Body descending will by reason of the perpetual action of the Diurnal motion receive from the aire in every one of those times in every several point of the streight line EA a several new and equal impulsion and therefore also in every one of those times it will acquire a several and equal degree of celerity And from hence it follows by that which Galilaeus hath in his Dialogues of Motion demonstrated that Heavy Bodies descend in the several times with such differences of transmitted spaces as are equal to the differences of the square numbers that succeed one another from Unity which square numbers being 1 4 9 16 c. their differences are 3 5 7 that is to say the odd numbers which succeed another from Unity Against this cause of Gravity which I have given it will perhaps be objected that if a Heavy Body be placed in the bottom of some hollow Cylinder of Iron or Adamant and the bottom be turned upwards the Body will descend though the aire above cannot depress it much less accelerate its motion But it is to be considered that there can be no Cylinder or Cavern but such as is supported by the Earth and being so supported is together with the Earth carried about by its diurnal Motion For by this means the bottom of the Cylinder will be as the Superficies of the Earth and by thrusting off the next and lowest aire will make the uppermost aire depress the Heavy Body which is at the top of the Cylinder in such manner as is above explicated 6 The Gravity of Water being so great as by experience wee find it is the reason is demanded by many why those that Dive how deep soever they go under water do not at all feel the weight of the water which lyes upon them And the cause seems to be this that all Bodies by how much the Heavier they are by so much the greater is the endeavour by which they tend downwards But the Body of a Man is Heavier then so much water as is equal to it in magnitude and therefore the endeavour downwards of a Mans Body is greater then that of water And seeing all endeavour is motion the Body also of a Man will be carried towards the bottom with greater Velocity then so much water Wherefore there is greater Reaction from the bottom and the Endeavour upwards is equal to the endeavour downwards whether the water be pressed by water or by another Body which is Heavier then water And therefore by these two opposite equal endeavours the endeavour both ways in the water is taken away and consequently those that Dive are not at all pressed by it Coroll From hence also it is manifest that water in water hath no Waight at all because all the parts of water both the parts above and the parts that are directly under tend towards the bottom with equal endeavour and in the same straight lines 7 If a Body float upon the water the waight of that Body is equal to the waight of so much water as would fill the place which the immersed part of the Body takes up within the water Let EF in the 3d figure be a Body floating in the water ABCD and let the part E be above and the other part F under the water I say the waight of the whole Body EF is equal to the waight of so much water as the Space F will receive For seeing the waight of the Body EF forceth the water out of the space F and placeth it upon the Superficies AB where it presseth downwards it follows that from the resistance of the bottom there will also be an endeavour upwards And seeing again that by this endeavour of the water upwards the Body EF is lifted up it follows that if the endeavour of the Body downwards be not equal to the endeavour of the water upwards either the whole Body EF will by reason of that inequality of their endeavours or moments be raised out of the water or else it will descend to the bottom But it is supposed to stand so as neither to ascend nor descend Wherefore there is an Aequilibrium between the two endeavours that is to say the waight of the Body EF is equal to the waight of so much water as the Space F will receive Which was to be proved 8 From hence it follows that any Body of how great magnitude soever provided it consist of matter less Heavy then water may nevertheless float upon any quantity of water how little soever Let ABCD in the 4th figure be a vessel and in it let EFGH be a Body consisting of matter which is less Heavy then water and let the space AGCF be filled with water I say the Body EFGH will not sink to the bottom DC For seeing the matter of the Body EFGH is less Heavy then Water if the whole space without ABCD were full of Water yet some part of the Body EFGH as EFIK would be above the Water and the waight of so much water as would fill the space IGHK would be equal to the waight of the whole Body EFGH and consequently GH would not touch the bottom DC As for the sides of the vessel it is no matter whether they be hard or fluid for they serve onely to terminate the Water which may be done as well by water as by any other matter how hard soever and the water without the Vessel is terminated somewhere so as that it can spread no further The part therefore EFIG will be extant above the water AGCF which is contained in the vessel Wherefore the Body EFGH will also float upon the water AGCF how little soever that water be which was to be demonstrated 9 In the 4th Article of the 26th Chapter there is brought for the proving of Vacuum the experiment of water enclosed in a vessel which water the Orifice above being opened is ejected upwards by the impulsion of the aire It is therefore demanded seeing water is Heavier then aire how that can be done Let the 2d figure of the same 26th Chap. be considered where the water is with great force injected by
Precepts but by exercising their feet This therefore may serve for the first Pace in the way to Philosophy In the next place I shall speak of the Faults and Errors into which men that reason unwarily are apt to fall and of their Kinds and Causes CHAP. V. Of Erring Falsity and Captions 1. Erring and Falsity how they differ Error of the Mind by it selfe without the use of Words how it happens 2 A sevenfold Incoherency of Names every one of which makes allwayes a false Proposition 3. Examples of the first manner of Incoherency 4 Of the second 5 Of the third 6 Of the fourth 7 Of the fifth 8 Of the sixth 9 Of the seventh 10 Falsity of Propositions detected by resolving the Terms with Definitions continued till they â—ome to Simple Names or Names that are the most Generall of their kind 11 Of the fault of a Syllogisme consisting in the Implication of the Termes which the Copula 12 Of the fault which consists in Equivocation 13 Sophisticall Captions are oftner faulty in the matter then in the forme of Syllogismes 1 MEn are subject to Erre not onely in Affiming and Denying but also in Perception and in silent Cogitation In Affirming and Denying when they call any thing by a Name which is not the Name thereof as if from seeing the Sun first by reflection in Water and afterwards again directly in the Firmament we should to both those appearances give the Name of Sunne and say there are two Sunnes which none but men can dâ—e for no other Living Creatures have the use of Names This kind of Error onely deserves the name of Falsity as arising not from sense nor from the Things themselves but from pronouncing rashly for Names have their constitution not from the Species of Things but from the Will and Consent of Men. And hence it comes to passe that men pronounce Falsely by their own negligence in departing from such appellations of things as are agreed upon and are not deceived neither by the Things nor by the Sense for they do not perceive that the thing they see is called Sunne but they give it that Name from their owne will and agreement Tacite Errors or the Errors of Sense and Cogitation are made by passing from one Imaginatition to the Imagination of another different thing or by feigning that to be Past or Future which never was nor ever shall be as when by seeing the Image of the Sunne in Water we imagine the Sunne it selfe to be there or by seeing swords that there has been or shall be fighting because it uses to be so for the most part or when from Promises we feigne the mind of the Promiser to be such and such or lastly when from any Signe we vainly imagine something to be signified which is not And Errors of this sort are common to all things that have sense and yet the Deception proceeds neither from our senses nor from the Things we perceive but from our selves while we feigne such things as are but meer Images to be something more then Images But neither Things nor Imaginations of Things can be said to be False seeing they are truly what they are nor doe they as Signes promise any thing which they do not performe for they indeed do not promise at all but we from them nor doe the Clouds but we from seeing the Clouds say it shall rain The best way therefore to free our selves from such Errors as arise from naturall Signes is first of all before we begin to reason concerning such conjecturall things to suppose our selves ignorant and then to make use of our Ratiocination for these Errors proceed from the want of Ratiocination whereas Errors which consist in Affirmation and Negation that is the Falsity of Propositions proceed only from Reasoning amisse Of these therefore as repugnant to Philosophy I will speake principally 2 Errors which happen in Reasoning that is in Syllogizing consist either in the Falsity of the Premisses or of the Inference In the first of these cases a Syllogisme is said to be faulty in the Matter of it and in the second case in the Forme I will first consider the Matter namely how many wayes a Proposition may be false and next the Forme and how it comes to pass that when the Premises are True the Inference is notwithstanding False Seeing therefore that Proposition onely is True Chap. 3. Art 7. in which are copulated two Names of one and the same thing and that alwayes False in which Names of different things are copulated look how many wayes Names of different things may be copulated and so many wayes a False Proposition may be made Now all things to which we give Names may be reduced to these four kinds namely Bodies Accidents Phantasmes and Names themselves and therefore in every true Proposition it is necessary that the Names copulated be both of them Names of Bodies or both Names of Accidents or both Names of Phantasmes or both Names of Names For Names otherwise copulated are incoherent and constitute a False Proposition It may happen also that the Name of a Body of an Accident or of a Phantasme may be copulated with the Name of a Speech So that copulated Names may be Incoherent seven manner of wayes 1 If the Name of a Body be copulated with the Name of an Accident 2 If the Name of a Body be copulated with the Name of a Phantasme 3 If the Name of a Body be copulated with the Name of a Name 4 If the Name of an Accident be copulated with the Name of a Phantasme 5 If the Name of an Accident be copulated with the Name of a Name 6 If the Name of a Phantasme be copulated with the Name of a Name 7 If the Name of a Body of an Accident or of a Phantasme be copulated with the Name of a Speech Of all which I will give some examples 3 After the first of these wayes Propositions are false when Abstract Names are copulated with Concrete Names as in Latine and Greek Esse est Ens Essentiâ— est Ens 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 i. Quidditas est Ens and many the like which are found in Aristotles Metaphysicks Also the Understanding worketh the Understanding understandeth the Sight seeth A Body is Magnitude A Body is Quantity A Body is Extension To Be a Man is a Man Whitenesse is a White thing c. which is as if one should say The Runner is the Running or the Walke Walketh Moreover Essence is separated Substance is Abstracted and others like these or derived from these with which common Philosophy abounds For seeing no Subject of an Accident that is No Body is an Accident no Name of an Accident ought to be given to a Body nor of a Body to an Accident 4 False in the second Manner are such Propositions as these A Ghost is a Body or a Spirit that is a thinne Body Sensible Species fly up and down in the Air or are moved hither and
alike and together with them and afterwards meeting with more Bodies like themselves they will unite and become greater Bodies Wherefore Homogeneous Bodies are congregated and Heterogenous dissipated by Simple Motion in a Medium where they naturally float Again such as being in a fluid Medium do not float but sink if the Motion of the fluid Medium be strong enough will be stirred up and carried away by that Motion and consequently they will be hindred from returning to that place to which they sink naturally and in which onely they would unite and out of which they are promiscuously carried that is they are disorderly mingled Now this Motion by which Homogeneous Bodies are congregated and Heterogeneous are scattered is that which is commonly called Fermentation from the Latine Fervere as the Greeks have their 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 which signifies the same from 〈◊〉 〈◊〉 〈◊〉 〈◊〉 〈◊〉 Ferveo For Seething makes all the parts of the Water change their places and the parts of any thing that is thrown into it will go several wayes according to their several natures And yet all Fervor or Seething is not caused by Fire for New Wine and many other things have also their Fermentation and Fervor to which Fire contributes little and some times nothing But when in Fermentation we find Heat it is made by the Fermentation 6 Fourthly in what time soever the Movent whose Center is A in the 2d figure moved in KLN shall by any number of revolutions that is when the Perimeters BI and KLN be commensurable have described a Line equal to the Circle which passes through the points B and I in the same time all the points of the floating Body whose Center is B shall return to have the same situation in respect of the Movent from which they departed For seeing it is as the distance BA that is as the Radius of the Circle which passes through BI is to the Perimeter it self BI so the Radius of the Circle KLN is to the Perimeter KLN and seeing the velocities of the points B and K are equal the time also of the revolution in IB to the time of one revolution in KLN will be as the Perimeter BI to the Perimeter KLN and therefore so many revolutions in KLN as together taken are equal to the Perimeter BI will be finished in the same time in which the whole Perimeter BI is finished therefore also the points L N F H or any of the rest will in the same time return to the same situation from which they departed and this may be demonstrated whatsoever be the points considered Wherefore all the points shall in that time return to the same situation which was to be proved From hence it follows that if the Perimeters BI and LKN be not commensurable then all the points wil never return to have the same situation or configuration in respect of one another 7 In Simple Motion if the Body moved be of a Spherical figure it hath less force towards its Poles then towards its middle to dissipate Heterogeneous or to congregate Homogeneous Bodies Let there be a Sphere as in the third figure whose Center is A and Diameter BC let it be conceived to be moved with Simple Circular Motion of which Motion let the Axis be the Straight Line DE cutting the Diameter BC at right angles in A. Let now the Circle which is described by any point B of the Sphere have BF for its Diameter and taking FG equal to BC and dividing it in the middle in H the Center of the Sphere A will when half a revolution is finished lie in H. And seeing HF and AB are equal a Circle described upon the Center H with the Radius HF or HG will be equal to the Circle whose Center is A and Radius AB And if the same Motion be continued the point B will at the end of another half revolution return to the place from whence it began to be moved and therefore at the end of half a revolution the point B will be carried to F and the whole Hemisphere DBE into that Hemisphere in which are the points L K and F. Wherfore that part of the fluid Medium which is cōtiguous to the point F will in the same time go back the length of the Straight Line BF and in the return of the point F to B that is of G to C the fluid Medium wil go back as much in a Straight Line from the point C. And this is the effect of Simple Motion in the middle of the Sphere where the distance from the Poles is greatest Let now the point I be taken in the same Sphere neerer to the Pole E and through it let the Straight Line IK be drawn parallel to the Straight Line BF cutting the arch FL in K the Axis HL in M then connecting HK upon HF let the perpendicular KN be drawn In the same time therefore that B comes to F the point I will come to K BF and IK being equal and described with the same velocity Now the Motion in IK to the fluid Medium upon which it works namely to that part of the Medium which is contiguous to the point K is oblique whereas if it proceeded in the Straight Line HK it would be perpendicular and therefore the Motion which proceeds in IK has less power then that which proceeds in HK with the same velocity But the Motions in HK and HF do equally thrust back the Medium and therefore the part of the Sphere at K moves the Medium less then the part at F namely so much less as KN is less then HF. Wherefore also the same Motion hath less power to disperse Heterogeneous and to congregate Homogeneous Bodies when it is neerer then when it is more remote from the Poles which was to be proved Corollary It is also necessary that in Plains which are perpendicular to the Axis and more remote then the Pole it self from the middle of the Sphere this Simple Motion have no effect For the Axis DE with Simple Motion describes the Superficies of a Cylinder and towards the Bases of the Cylinder there is in this Motion no endeavour at all 8 If in a fluid Medium moved about as hath been said with Simple Motion there be conceived to float some other Spherical Body which is not fluid the parts of the Medium which are stopped by that Body will endeavour to spread themselves every way upon the Superficies of it And this is manifest enough by experience namely by the spreading of water poured out upon a pavement But the reason of it may be this Seeing the Sphere A in the 3d figure is moved towards B the Medium also in which it is moved will have the same Motion But because in this Motion it falls upon a Body not liquid as G so that it cannot go on and seeing the small parts of the Medium can not go forwards
all Opinions concerning the nature of Infinite and Eternal known onely to himself should as the first-fruits of Wisdom be judged by those whose Ministery he meant to use in the ordering of Religion I cannot therefore commend those that boast they have demonstrated by reasons drawn from natural things that the World had a Beginning They are contemned by Idiots because they understand them not and by the Learned because they understand them by both deservedly For who can commend him that demonstrates thus If the World be Eternal then an infinite number of dayes or other measures of Time preceded the birth of Abraham But the birth of Abraham preceded the birth of Isaac and therefore one Infinite is greater then another Infinite or one Eternal then another Eternal which he sayes is absurd This Demonstration is like his who from this that the number of even Numbers is infinite would conclude that there are as many even Numbers as there are Numbers simply that is to say the even Numbers are as many as all the even and od together They which in this manner take away Eternity from the World do they not by the same means take away Eternity from the Creator of the Woâ—ld From this absurdity therefore they run into another being forced to call Eternity Nunc stans a standing still of the present Time or an abiding Now and which is much more absurd to give to the infinite number of Numbers the name of Unity But why should Eternity be called an Abiding Now rather then an Abiding Then Wherefore there must either be many Eternities or Now and Then must signifie the same With such Demonstrators as these that speak in another language it is impossible to enter into disputation And the men that reason thus absurdly are not Idiots but which makes the absurdity unpardonable Geometricians and such as take upon them to be Judges impertinent but severe Judges of other mens Demonstrations The reason is this that as soon as they are entangled in the Words Infinite and Eternal of which we have in our mind no Idea but that of our own insufficiency to comprehend them they are forced either to speak something absurd or which they love worse to hold their peace For Geometry hath in it somewhat like Wine which when new is windy but afterwards though less pleasant yet more wholsome Whatsoever therefore is true young Geometricians think Demonstrable but elder not Wherefore I purposely pass over the Questions of Infinite and Eternal contenting my self with that Doctrine concerning the Beginning and Magnitude of the World which I have been perswaded to by the holy Scriptures and fame of the Miracles which confirm them and by the Custome of my Country and reverence due to the Laws And so I pass on to such things as it is not unlawful to dispute of 2 Concerning the World it is further questioned whether the parts thereof be contiguous to one another in such manner as not to admit of the least empty space between and the disputation both for against it is carried on with probability enough For the taking away of Vacuum I will instance in onely one experiment a common one but I think unanswerable Let AB in the first fig. represent a vessel such as Gardiners use to water their Gardens withal whose bottom B is ful of litle holes whose mouth A may be stopt with ones finger when there shall be need If now this vessel be filled with water the hole at the top A being stopt the water will not flow out at any of the holes in the bottom B. But if the finger be removed to let in the air above it will run out at them all and as soon as the finger is applyed to it again the water wil suddenly totally be stayed again from running out The cause whereof seems to be no other but this that the Water cannot by its natural endeavour to descend drive down the aire below it because there is no place for it to go into unless either by thrusting away the next contiguous aire it proceed by continual endeavour to the hole A where it may enter and succeed into the place of the water that floweth out or else by resisting the endeavour of the water Downwards penetrate the same and pass up through it By the first of these wayes while the hole at A remains stopped there is no possible passage nor by the second unless the holes be so great that the water flowing out at them can by its own waight force the Air at the same time to ascend into the vessel by the same holes as we see it does in a vessel whose mouth is wide enough when we turn suddenly the bottom upwards to poure out the water for then the Aire being forced by the waight of the water enters as is evident by the sobbing and resistance of the water at the sides or circumference of the orifice And this I take for a sign that all Space is full for without this the naturall motion of the water which is a heavy Body downwards would not be hindered 3 On the contrary for the establishing of Vacuum many specious arguments and experiments have been brought Neverthelesse there seemes to be something wanting in all of them to conclude it firmely These arguments for Vacuum are partly made by the followers of the doctrine of Epicurus who taught that the World consists of very small Spaces not filled by any Bodie and of very small Bodies that have within them no empty Space which by reason of their hardnesse he calls Atomes and that these small Bodies and Spaces are every where intermingled Their arguments are thus delivered by Lucretius And first he sayes that unlesse it were so there could be no motion For the office and property of Bodies is to withstand and hinder motion If therfore the Universe were filled with Body motion would every where be hindered so as to have no beginning any where consequently there would be no motion at all It is true that in whatsoever is full and at rest in all its parts it is not possible motion should have beginning But nothing is drawn from hence for the proving of Vacuum For though it should be granted that there is Vacuum yet if the Bodies which are intermingled with it should all at once and together be at rest they would never be moved again For it has been demonstrated above in the 9th Chapter 7th Article that nothing can be moved but by that which is contiguous and already moved But supposing that all things are at rest together there can be nothing contiguous and moved and therefore no beginning of motion Now the denying of the beginning of motion doth not take away present motion unless beginning be taken away from Body also For motion may be either coeternal or concreated with Body Nor doth it seem more necessary that Bodies were first at rest and afterwards moved then that they were
first moved and rested if ever they rested at all afterwards Neither doth there appear any cause why the matter of the World should for the admission of motion be intermingled with empty spaces rather then full I say full but withall fluid Nor lastly is there any reason why those hard Atomes may not also by the motion of intermingled fluid matter be congregated brought together into compounded Bodies of such bigness as we see Wherefore nothing can by this argument be concluded but that motion was either coeternal or of the same duration with that which is moved neither of which conclusions consisteth with the doctrine of Epicurus who allows neither to the World nor to Motion any Beginning at all The necessity therefore of Vacuum is not hitherto demonstrated And the cause as far as I understand from them that have discoursed with me of Vacuum is this that whilest they contemplate the nature of Fluid they conceive it to consist as it were of small grains of hard matter in such manner as meal is fluid made so by grinding of the Corn when nevertheless it is possible to conceive Fluid to be of its own nature as homogeneous as either an Atome or as Vacuum it self The second of their arguments is taken from waight and is contained in these Verses of Lucretius Corporis officium est quoniam premere omnia deorsum Contrà autem natura manet sine Pondere Inanis Ergo quod magnum est aeque Leviusque videtur Nimirum plus esse sibi declarat Inanis That is to say Seeing the office and property of Body is to press all things downwards and on the contrary seeing the nature of Vacuum is to have no waight at all Therefore when of two Bodies of equal magnitude one is lighter then the other it is manifest that the lighter Body hath in it more Vacuum then the other To say nothing of the Assumption concerning the endeavour of Bodies downwards which is not rightly assumed because the World hath nothing to do with Downwards which is a mere fiction of ours Nor of this that if al things tended to the same lowest part of the World either there would be no coalescence at all of Bodies or they would all be gathered together into the same place This onely is sufficient to take away the force of the argument that Aire intermingled with those his Atomes had served as well for his purpose as his intermingled Vacuum The third argument is drawn from this That Lightning Sound Heat and Cold do penetrate all Bodies except Atomes how solid soever they be But this reason except it be first demonstrated that the same things cannot happen without Vacuum by perpetual generation of Motion is altogether invalid But that all the same things may so happen shall in due place be demonstrated Lastly the fourth argument is set down by the same Lucretius in these Verses Duo de concursu corpora lata Si citò dissiliant nempe aer omne necesse est Inter corpora quod fuerat possidat Inane Is porro quamvis circum celerantibus auris Confluat haud poterit tamen uno tempore totum Compleri spatium nam primum quemque necesse est Occupet ille locum deinde omnia possideantur That is If two flat Bodies be suddenly pulled asunder of necessity the Air must come between them to fill all the space they left empty But with what celerity soever the Air flow in yet it cannot in one instant of time fill the whole space but first one part of it then successively all Which nevertheless is more repugnant to the opinion of Epicurus then of those that deny Vacuum For though it be true that if two Bodies were of infinite hardness and were joyned together by their Superficies which were most exactly plain it would be impossible to pull them asunder in regard it could not be done but by Motion in an instant yet if as the greatest of all Magnitudes cannot be given nor the swiftest of all Motions so neither the hardest of all hard Bodies it might be that by the application of very great force there might be place made for a successive flowing in of the Aire namely by separating the parts of the joyned Bodies by succession beginning at the outermost and ending at the innermost part He ought therefore first to have proved that there are some Bodies extreamly hard not relatively as compared with softer Bodies but absolutely that is to say infinitely hard which is not true But if we suppose as Epicurus doth that Atomes are indivisible and yet have small superficies of their own then if two Bodies should be joyned together by many or but one onely small superficies of either of them then I say this argument of Lucretius would be a firme demonstration that no two Bodies made up of Atomes as he supposes could ever possibly be pulled asunder by any force whatsoever But this is repugnant to daily experience And thus much of the arguments of Lucretius Let us now consider the arguments which are drawn from the experiments of later Writers 4 The first experiment is this That if a hollow vessel be thrust into water with the bottom upwards the water will ascend into it which they say it could not do unless the Aire within were thrust together into a narrower place and that this were also impossible except there were little empty places in the Aire Also that when the Aire is compressed to a certain degree it can receive no further compression its small particles not suffering themselves to be pent into less room This reason if the Aire could not pass through the Water as it ascends within the vessel might seem valid But it is sufficiently known that Aire will penetrate Water by the application of a force equal to the gravity of the Water If therefore the force by which the Vessel is thrust down be greater or equal to the endeavour by which the water naturally tendeth downwards the Aire will go out that way where the resistance is made namely towards the edges of the Vessel For by how much the deeper is the water which is to be penetrated so much greater must be the depressing force But after the Vessel is quite under water the force by which it is depressed that is to say the force by which the water riseth up is no longer encreased There is therefore such an equilibration between them as that the natural endeavour of the water downwards is equal to the endeavour by which the same water is to be penetrated to the encreased depth The second experiment is That if a concave Cylinder of sufficient length made of Glass that the experiment may be the better seen having one end open and the other close shut be filled with Quicksilver and the open end being stopped with ones finger be together with the finger dipped into a dish or other vessel in which also there is Quicksilver and the Cylinder be set upright we
shall the finger being taken away to make way for the descent of the Quicksilver see it descend into the Vessel under it till there be onely so much remayning within the Cylinder as may fill about 26 Inches of the same and thus it will alwayes happen whatsoever be the Cylinder provided that the length be not less then 26 Inches From whence they conclude that the cavity of the Cylinder above the Quicksilver remayns empty of all Body But in this experiment I finde no necessity at all of Vacuum For when the Quicksilver which is in the Cylinder descends the Vessel under it must needs be filled to a greater height and consequently so much of the contiguous Air must be thrust away as may make place for the Quicksilver which is descended Now if it be asked whether that Aire goes what can be answered but this that it thrusteth away the next Aire that the next so successively till there be a return to the place where the propulsion first began and there the last Aire thus thrust on will press the Quicksilver in the Vessel with the same force with which the first Aire was thrust away and if the force with which the Quicksilver descends be great enough which is greater or less as it descends from a place of greater or less height it will make the Aire penetrate the Quicksilver in the vessel and go up into the Cylinder to fill the place which they thought was left empty But because the Quicksilver hath not in every degree of height force enough to cause such penetration therefore in descending it must of necessity stay somewhere namely there where its endeavour downwards and the resistance of the same to the penetration of the Aire come to an aequilibrium And by this experiment it is manifest that this aequilibrium will be at the height of 26 Inches or thereabouts The third experiment is That when a Vessel hath as much Air in it as it can naturally contain there may nevertheless be forced into it as much water as will fill three quarters of the same Vessel And the experiment is made in this manner Into the glass bottle represented in the 2d figure by the Sphere F G whose center is A let the pipe B A C be so fitted that it may precisely fill the mouth of the bottle and let the end B be so neer the bottom that there may be onely space enough left for the free passage of the water which is thrust in above Let the upper end of this pipe have a Cover at D with a spout at E by which the water when it ascends in the pipe may run out Also let H C be a Cock for the opening or shutting of the passage of the water between B and D as there shall be occasion Let the Cover D E be taken off and the Cock H C being opened let a Syringe fall of water be forced in and before the Syringe be taken away let the Cock be turned to hinder the going out of the Aire And in this manner let the injection of water be repeated as often as it shall be requisite till the water rise within the bottle for example to G F. Lastly the Cover being fastened on again and the Cock H C opened the water will run swiftly out at E and sink by little and little from G F to the bottom of the pipe B. From this Phaenomenon they argue for the necessity of Vacuum in this manner The Bottle from the beginning was full of Aire which Aire could neither go out by penetrating so great a length of water as was injected by the pipe nor by any other way Of necessity therefore all the water as high as F G as also all the Aire that was in the bottle before the water was forced in must now be in the same place which at first was filled by the Aire alone which were impossible if all the space within the bottle were formerly filled with Aire precisely that is without any Vacuum Besides though some man perhaps may think the Air being a thinne Body may pass through the Body of the water contained in the pipe yet from that other Phaenomenon namely that all the water which is in the space B F G is cast out again by the spout at E for which it seems impossible that any other reason can be given besides the force by which the Aire frees it self from compression it follows that either there was in the bottle some space empty or that many Bodies may be together in the same place But this last is absurd and therefore the former is true namely that there was Vacuum This argument is infirm in two places For first that is assumed which is not to be granted and in the second place an experiment is brought which I think is repugnant to Vacuum That which is assumed is that the Aire can have no passage out through the pipe Nevertheless we see daily that Aire easily ascends from the bottom to the Superficies of a River as is manifest by the bubbles that rise nor doth it need any other cause to give it this motion then the natural endeavour downwards of the Water Why therefore may not the endeavour upwards of the same Water acquired by the injection which endeavour upwards is greater then the natural endeavour of the water downwards cause the aire in the bottle to penetrate in like manner the water that presseth it downwards especially seeing the water as it riseth in the bottle doth so press the Aire that is above it as that it generateth in every part thereof an endeavour towards the external superficies of the pipe and consequently maketh all the parts of the enclosed aire to tend directly towards the passage at B I say this is no less manifest then that he aire which riseth up from the bottom of a River should penetrate the water how deep soever it be Werefore I do not yet see any cause why the force by which the water is injected should not at the same time eject the aire And as for their arguing the necessity of Vacuum from the rejection of the water In the first place supposing there is Vacuum I demand by what principle of motion that ejection is made Certainly seeing this motion is from within outwards it must needs be caused by some Agent within the bottle that is to say by the aire it self Now the motion of that aire being caused by the rising of the water begins at the bottom and tends upwards whereas the motion by which it ejecteth the water ought to begin above and tend downwards From whence therefore hath the enclosed aire this endeavour towards the bottom To this question I know not what answer can be given unless it be said that the aire descends of its own accord to expel the water Which because it is absurd and that the aire after the water is forced in hath as much room as its magnitude requires there
will remain no cause at all why the water should be forced out Wherefore the assertion of Vacuum is repugnant to the very experiment which is here brought to establish it Many other Phaenomena are usually brought for Vacuum as those of Weather-glasses Aeolipiles Wind-guns c. Which would all be very hard to be salved unless water be penetrable by aire without the intermixture of empty space But now seeing aire may with no great endeavour pass through not onely water but any other fluid Body though never so stubborn as Quicksilver these Phaenomena prove nothing Nevertheless it might in reason be expected that he that would take away Vacuum should without Vacuum shew us such causes of these Phaenomena as should be at least of equal if not greater probability This therefore shall be done in the following discourse when I come to speak of these Phaenomena in their proper places But first the most general Hypotheses of natural Philosophy are to be premised And seeing that Suppositions are put for the true Causes of apparent Effects every Supposition except such as be absurd must of necessity consist of some supposed possible Motion for Rest can never be the Essicient Cause of any thing Motion supposeth Bodies Moveable of which there are three kinds Fluid Consistent and mixt of both Fluid are those whose parts may by very weak endeavonr be separated from one another and Consistent those for the separation of whose parts greater force is to be applyed There are therefore degrees of Consistency which degrees by comparison with more or less Consistent have the names of Hardness or Softness Wherefore a Fluid Body is alwayes divisible into Bodies equally Fluid as Quantity into Quantities and Soft Bodies of whatsoever degree of Softness into Soft Bodies of the same degree And though many men seem to conceive no other difference of Fluidity but such as ariseth from the different magnitudes of the parts in which Sense Dust though of Diamonds may be called Fluid Yet I understand by Fluidity that which is made such by Nature equally in every part of the Fluid Body not as Dust is Fluid for so a House which is falling in pieces may be called Fluid but in such manner as Water seems Fluid and to divide it self into parts perpetually Fluid And this being well understood I come to my Suppositions 5 First therefore I suppose That the Immense Space which we call the World is the Aggregate of all Bodies which are either Consistent Visible as the Earth and the Starres or Invisible as the small Atomes which are disseminated through the whole space between the Earth and the Stars and lastly that most Fluid Aether which so fils all the rest of the Universe as that it leaves in it no empty place at all Secondly I suppose with Copernicus That the greater Bodies of the World which are both consistent and permanent have such order amongst themselves as that the Sunne hath the first place Mercury the second Venus the third The Earth with the Moon going about it the fourth Mars the fifth Jupiter with his Attendants the sixth Saturne the seventh and after these the Fixed Starres have their several distances from the Sunne Thirdly I suppose That in the Sunne the rest of the Planets there is and alwayes has been a Simple Circular Motion Fourthly I suppose That in the Body of the Aire there are certain other Bodies intermingled which are not Fluid but withal that they are so small that they are not preceptible by Sense and that these also have their proper Simple Motion and are some of them more some less hard or consistent Fifthly I suppose with Kepler That as the distance between the Sunne and the Earth is to the distance between the Moon and the Earth so the distance between the Moon and the Earth is to the Semidiameter of the Earth As for the Magnitude of the Circles and the Times in which they are described by the Bodies which are in them I will suppose them to be such as shall seem most agreeable to the Phaenomena in question 6 The causes of the different Seasons of the Year and of the several variations of Dayes and Nights in all the parts of the superficies of the Earth have been demonstrated first by Copernicus and since by Kepler Galilaeus and others from the supposition of the Earths diurnal revolution about its own Axis together with its Annual motion about the Sunne in the Ecliptick according to the order of the Signes and thirdly by the annual revolution of the same Earth about its own center contrary to the order of the Signs I suppose with Copernicus That the diurnal revolution is from the motion of the Earth by which the Aequinoctial Circle is described about it And as for the other two annual motions they are the efficient cause of the Earths being carried about in the Ecliptick in such manner as that its Axis is alwayes kept parallel to it self Which parallelisme was for this reason introduced lest by the Earths annual revolution its Poles should seem to be necessarily carried about the Sunne contrary to experience I have in the 10th Artic. of the â—â—th Chap. demonstrated from the supposition of Simple Circular Motion in the Sun that the Earth is so carried about the Sunne as that its Axis is thereby kept always parallel to it self Wherefore from these two supposed motions in the Sunne the one Simple Circular Motion the other Circular Motion about its owns Center it may be demonstrated that the Year hath both the same variations of Dayes and Nights as have been demonstrated by Copernicus For if the Circle abcd in the 3d Figure be the Ecliptick whose Center is e and Diameter aec and the Earth be placed in a the Sunne be moved in the little Circle fghi namely according to the order f g h i it hath been demonstrated that a Body placed in a will be moved in the same order through the points of the Ecliptick a b c d and will alwayes keep its Axis parallel to its self But if as I have supposed the Earth also be moved with Simple Circular Motion in a plain that passeth through a cutting the plain of the Ecliptick so as that the common section of both the plains be in ac thus also the Axis of the Earth will be kept alwayes parallel to it self For let the Center of the Earth be moved about in the Circumference of the Epicycle whose Diameter is lak which is a part of the straight line lac Therefore lak the Diameter of the Epicycle passing through the Center of the Earth will be in the plain of the Ecliptick Wherefore seeing that by reason of the Earths Simple Motion both in the Ecliptick and in its Epicycle the straight line lak is kept alwayes parallel to it self every other straight line also taken in the Body of the Earth and consequently its Axis will in like manner be kept alwayes parallel
reach the Zodiack of the fixed Starres wil fall stil upon the same fixed Starres because the whole Orbe a b c d is supposed to have no magnitude at all in respect of the great distance of the fixed Starres Supposing now the Sun to be in c it remains that I shew the cause why the Earth is neerer to the Sunne when in its annual motion it is found to be in d then when it is in b. And I take the cause to be this When the Earth is in the beginning of Capricorn at b the Sunne appears in the beginning of Cancer at d then is the midst of Summer But in the midst of Summer the Northern parts of the Earth are towards the Sunne which is almost all dry land containing all Europe and much the greatest part of Asia and America But when the Earth is in the beginning of Cancer at d it is the midst of Winter and that part of the Earth is towards the Sunne which contains those great Seas called the South Sea and the Indian Sea which are of farre greater extent then all the dry Land in that Hemisphere Wherefore by the last Article of the 21 Chapter when the Earth is in d it will come neerer to its first Movent that is to the Sunne which is in t that is to say the Earth is neerer to the Sunne in the midst of Winter when it is in d then in the midst of Summer when it is b and therefore during the Winter the Sunne is in its Perigaeum and in its Apogaeum during the Summer And thus I have shewn a possible cause of the Excentricity of the Earth which was to be done I am therefore of Keplers opinion in this that he attributes the Excentricity of the Earth to the difference of the parts thereof and supposes one part to be affected and another disaffected to the Sunne And I dissent from him in this that he thinks it to be by Magnetick virtue and that this Magnetick virtue or attraction and thrusting back of the Earth is wrought by immateriate Species which cannot be because nothing can give motion but a Body moved and contiguous For if those Bodies be not moved which are contiguous to a Body unmoved how this Body should begin to be moved is not imaginable as has been demonstrated in the 7th Article of the 9th Chapter and often inculcated in other places to the end that Philosophers might at last abstain from the use of such unconceiveable connexions of words I dissent also from him in this that he says the similitude of Bodies is the cause of their mutual attraction For if it were so I see no reason why one Egg should not be attracted by another If therefore one part of the Earth be more affected by the Sunne then another part it proceeds from this that one part hath more water the other more dry land And from hence it is as I shewed above that the Earth comes neerer to the Sunne when it shines upon that part where there is more water then when it shines upon that where there is more dry Land 9 This Excentricity of the Earth is the cause why the way of its annual motion is not a perfect Circle but either an Elliptical or almost an Elliptical line as also why the Axis of the Earth is not kept exactly parallel to it self in all places but onely in the Equinoctial points Now seeing I have said that the Moon is carried about by the Earth in the same manner that the Earth is by the Sunne and that the Earth goeth about the Sunne in such manner as that it shews sometimes one Hemisphere sometimes the other to the Sunne it remains to be enquired why the Moon has alwayes one and the same face turned towards the Earth Suppose therefore the Sunne to be moved with Simple Motion in the little Circle f g h i in the fourth figure whose Center is t and let ♈ ♋ ♎ ♑ be the annuall Circle of the Earth and a the beginning of Libra About the point a let the little Circle l k be described and in it let the Center of the Earth be understood to be moved with Simple motion and both the Sunne the Earth to be moved according to the order of the Signes Upon the Center a let the way of the Moon m n o p be described and let q r be the Diameter of a Circle cutting the Globe of the Moon into two Hemispheres whereof one is seen by us when the Moon is at the full and the other is turned from us The Diameter therefore of the Moon q o r will be perpendicular to the Straight Line t a. Wherefore the Moon is carried by reason of the Motion of the Earth from o towards p. But by reason of the motion of the Sunne if it were in p it would at the same time be carried from p towards o and by these two contrary Movents the straight line q r will be turned about and in a Quadrant of the Circle m n o p it will be turned so much as makes the fourth part of its whole conversion Wherefore when the Moon is in p q r will be parallel to the straight line m o. Secondly when the Moon is in m the straight line q r will by reason of the motion of the Earth be in m o. But by the working of the Suns motion upon it in the quadrant p m to◠same q r will be turned so much as makes another quarter of its whole conversion When therefore the Moon is in m q r will be perpendicular to the straight line o m. By the same reason when the Moon is in n q r will be parallel to the straight line m o and the Moon returning to o the same q r will return to its first place and the Body of the Moon will in one entire period make also one entire conversion upon her own Axis In the making of which it is manifest that one and the same face of the Moon is always turned towards the Earth And if any Diameter were taken in that little Circle in which the Moon were supposed to be carried about with simple motion the same effect would follow for if there were no action from the Sun every Diameter of the Moon would be carried about always parallel to it self Wherefore I have given a possible cause why one and the same face of the Moon is alwayes turned towards the Earth But it is to be noted that when the Moon is without the Ecliptick we do not alwayes see the same face precisely For we see onely that part which is illuminated But when the Moon is without the Ecliptick that part which is towards us is not exactly the same with that which is illuminated 10 To these three simple motions one of the Sunne another of the Moon and the third of the Earth in their own little Circles f g h i l k q r together with the Diurnal
of this Evocation and Swelling and such as agreeth with the rest of the Phaenomena of Heat may be thought to have given the cause of the Heat of the Sunne It hath been shewn in the 5 article of the 21 chapter that the fluid Medium which we call the Aire is so moved by the simple circular motion of the Sunne as that all its parts even the least do perpetually change places with one another which change of places is that which there I called Fermentation From this Fermentation of the Aire I have in the 8 article of the last chapter demonstrated that the water may be drawn up into the clouds And I shall now shew that the fluid parts may in like manner by the same Fermentation be drawn out from the internall to the externall parts of our Bodies For seeing that wheresoever the fluid Medium is contiguous to the Body of any living creature there the parts of that Medium are by perpetuall change of place separated from one another the contiguous parts of the living creature must of necessity endeavour to enter into the spaces of the separated parts For otherwise those parts supposing there is no Vacuum would have no place to go into And therefore that which is most fluid and separable in the parts of the living creature which are contiguous to the Medium will go first out and into the place thereof will succeed such other parts as can most easily transpire through the poâ—es of the skin And from hence it is necessary that the rest of the parts which are not separated must all together be moved outwards for the keeping of all places full But this motion outwards of all parts together must of necessity press those parts of the ambient Aire which are ready to leave their places and therefore all the parts of the Body endeavouring at once that way makes the Body swell Wherefore a possible cause is given of Heat from the Sunne which was to be done 4 We have now seen how Light and Heat are generated Heat by the simple motion of the Medium making the parts perpetually change places with one another and Light by this that by the same simple motion Action is propagated in a straight line But when a Body hath its parts so moved that it sensibly both Heats and Shines at the same time then it is that we say Fire is generated Now by Fire I do not understand a Body distinct from matter combustible or glowing as Wood or Iron but the matter it self not simply and always but then onely when it shineth and heateth He therefore that renders a cause possible and agreeable to the rest of the Phaenomena namely whence and from what action both the Shining and Heating proceed may be thought to have given a possible cause of the generation of Fire Let therefore ABC in the first Figure be a Sphere or the portion of a Sphere whose Center is D and let it be transparent and homogeneous as Cristal Glass or Water and objected to the Sunne Wherefore the foremost part ABC will by the simple motion of the Sunne by which it thrusts forwards the Medium be wrought upon by the Sun-beams in the straight lines EA FB and GC which straight lines may in respect of the great distance of the Sunne be taken for parallels And seeing the Medium within the Sphere is thicker then the Medium without it those Beams will be refracted towards their perpendiculars Let the straight lines EA and GC be produced till they cut the Sphere in H and I and drawing the perpendiculars AD and CD the refracted Beams EA and GC will of necessity fall the one between AH and AD the other between CI and CD Let those refracted Beams be AK and CL. And again let the lines DKM DLN be drawn perâ—endicular to the Sphere and let AK and CL be produced till they meet with the straight line BD produced in O. Seeing therefore the Medium within the Sphere is thicker then that without it the refracted line AK will recede further from the perpendicular KM then KO will recede from the same Wherefore KO will fall between the refracted line and the perpendicular Let therefore the refracted line be KP cutting FO in P and for the same reason the straight line LP will be the refracted line of the straight line CL. Wherfore seeing the Beams are nothing else but the Wayes in which the motion is propagated the motion about P will be so much more vehement then the motion about ABC by how much the base of the portion ABC is greater then the base of a like portion in the Sphere whose Center is P and whose magnitude is equal to that of the little Circle about P which comprehendeth all the Beams that are propagated from ABC and this Sphere being much less then the Sphere ABC the parts of the Medium that is of the Aire about P will change places with one another with much greater celerity then those about ABC If therefore any matter Combustible that is to say such as may be easily dissipated be placed in P the parts of that matter if the proportion be great enough between AC and a like portion of the little circle about P wil be freed from their mutual cohaesion and being separated will acquire simple motion But vehement simple motion generates in the beholder a Phantasm of Lucid and Hot as I have before deâ—onstrated of the simple motion of the Sunne and therefore the combustible matter which is placed in P will be made Lucid and Hot that is to say will be Fire Wherefore I have rendered a possible cause of Fire which was to be done 5 From the manner by which the Sunne generateth Fire it is easy to explaine the manner by which Fire may be generated by the collision of two Flints For by that Collision some of those particles of which the stone is compacted are violently separated and thrown off and being withall swiftly turned round the Eie is moved by them as it is in the generation of Light by the Sunne Wherefore they shine and falling upon matter which is already halfe dissipated such as is Tinder they throughly dissipate the parts thereof and make them turn round From whence as I have newly shewn Light and Heat that is to say Fire is generated 6 The shining of Glow-worms some kinds of Rotten Wood and of a kinde of stone made at Bolognia may have one common cause namely the exposing of them to the hot Sunne We finde by experience that the Bolonian stone shines not unless it be so exposed and after it has been exposed it shines but for a little time namely as long as it retains a certain degree of heat And the cause may be that the parts of which it is made may together with heat have Simple Motion imprinted in them by the Sunne Which if it be so it is necessary that it shine in the dark as
as it is in the triangle CGK which is neerest to the First Light the transverse beames make Greenesse and when the same Second Light is weaker as in the triangle CKL they make a Purple colour 14 From hence may be deduced a cause why the Moon and Starres appear bigger and redder neer the Horizon then in the Mid-heaven For between the Eie and the apparent Horizon there is more impure aire such as is mingled with Watery and Earthy little Bodies then is between the same Eie and the more elevated part of Heaven But Vision is made by Beames which constitute a Cone whose base if we look upon the Moon is the Moons Face and whose vertex is in the Eie and therefore many beams from the Moon must needs fall upon little Bodies that are without the Visual Cone and be by them reflected to the Eie But these reflected beams tend all in lines which are transverse to the Visual Cone and make at the Eie an angle which is greater then the angle of the Cone Wherefore the Moon appeares greater in the Horizon then when she is more elevated And because those reflected beames go transversely there will be generated by the last article Rednesse A possible cause therefore is shewne why the Moon as also the Starres appear Greater and Redder in the Horizon then in the midst of heaven The same also may be the cause why the Sunne appears in the Horizon Greater and of a colour more degenerating to Yellow then when he is higher elevated For the reflection from the little Bodies between and the transverse motion of the Medium are still the same But the Light of the Sunne is much stronger then that of the Moon and therefore by the last article his Splendor must needs by this perturbation degenerate into Yellownesse But for the generation of these four colours it is not necessary that the figure of the Glass be a Prisma for if it were Spherical it would doe the same For in a Sphere the Sunne-beames are twice refracted and twice reflected And this being observed by Des Cartes and with all that a Rainebow never appeares but when it rains as also that the drops of raine have their figures almost Spherical he hath shewne from thence the cause of the colours in the Rainbow which therefore need not be repeated 15 Whiteness is Light but Light perturbed by the reflexions of many beams of Light comming to the Eye together within a little space For if Glass or any other Diaphanous Body be reduced to very small parts by contusion or concussion every one of those parts if the Beams of a lucid Body be from any one point of the same reflected to the Eye will represent to the beholder an Idea or Image of the whole lucid Body that is to say a Phantasme of White For the strongest Light is the most White and therefore many such parts will make many such Images Wherefore if those parts lie thick and close together those many Images will appear confusedly and will by reason of the confused Light represent a White Colour So that from hence may be deduced a possible cause why Glass beaten that is reduced to powder looks White Also why Water and Snow are White they being nothing but a heap of very small Diaphanous Bodies namely of little Bubbles from whose several convex Superficies there are by reflexion made several confused Phantasmes of the whole lucid Body that is to say Whiteness For the same reason Salt and Nitre are White as consisting of small Bubbles which contain within them Water and Aire as is manifest in Nitre from this that being thrown into the fire it violently blowes the same which Salt also doth but with less violence But if a White Body be exposed not to the Light of the Day but to that of the Fire or of a Candle it will not at the first sight be easily judged whether it be White or Yellow the cause whereof may be this that the light of those things which burn and flame is almost of a middle Colour between Whiteness and Yellowness 16 As Whiteness is Light so Blackness is the privation of Light or Darkness And from hence it is First that all Holes from which no light can be reflected to the Eie appear Black Secondly that when a Body hath little eminent particles erected straight up from the Superficies so that the Beams of Light which fall upon them are reflected not to the Eie but to the Body it self that Superficies appears Black in the same manner as the Sea appears Black when ruffled by the Wind. Thirdly that any combustible matter is by the fire made to look Black before it shines For the endeavour of the fire being to dissipate the smallest parts of such Bodies as are thrown into it it must first raise and erect those parts before it can work their dissipation If therefore the fire be put out before the parts be totally dissipated the Cole will appear Black for the parts being onely erected the Beams of Light falling upon them will not be reflected to the Eie but to the Cole it self Fourthly that Burning Glasses do more easily burn Black things then White For in a White Superficies the eminent parts are convex like little bubbles and therefore the Beams of Light which fall upon them are reflected every way from the reflecting Body But in a Black Superficies where the eminent particles are more erected the Beams of Light falling upon them are all necessarily reflected towards the Body it self and therefore Bodies that are Black are more easily set on fire by the Sun-beams then those that are White Fifthly that all Colours that are made of the mixture of White and Black proceed from the different position of the particles that rise above the Superficies and their different forms of asperity For according to these differences more or fewer Beams of Light are reflected from several Bodies to the Eie But in regard those differences are innumerable and the Bodies themselves so small that we cannot perceive them the explication and precise determination of the Causes of all Colours is a thing of so great difficulty that I dare not undertake it CHAP. XXVIII Of Cold Wind Hard Ice Restitution of Bodies bent Diaphanous Lightning and Thunder and of the Heads of Rivers 1 Why Breath from the same mouth sometimes heats and sometimes cools 2 Wind and the Inconstancy of Winds whence 3 Why there is a constant though not a great Wind from East to West neer the Equator 4 What is the effect of Aire pent in between the Clouds 5 No change from Soft to Hard but by motion 6 What is the cause of Cold neer the Poles 7 The cause of Ice and why the Cold is more remiss in rainy then in clear weather Why water doth not freeze in deep Wells as it doth neer the Superficies of the Earth Why Ice is not so heavy as Water and why Wine is not so easily frozen
as Water 8 Another cause of Hardness from the fuller contact of Atomes Also how Hard things are broken 9 A third cause of Hardness from Heat 10 A fourth cause of Hardness from the motion of Atomes enclosed in a narrow space 11 How Hard things are Softned 12 Whence proceeds the spontaneous Restitution of things Bent. 13 Diaphanous and Opacous what they are and whence 14 The cause of Lightning and Thunder 15 Whence it proceeds that Clouds can fall again after they are once elevated and frozen 16 How it could be that the Moon was eclipsed when she was not diametrally opposite to the Sunne 17 By what means many Sunnes may appear at once 18 Of the Heads of Rivers 1 AS when the motion of the ambient aethereal substance makes the Spirits and fluid parts of our Bodies tend outwards we acknowledge Heat so by the endeavour inwards of the same spirits and humours we feel Cold. So that to Cool is to make the exterior parts of the Body endeavour inwards by a motion contrary to that of Calefaction by which the internal parts are called outwards He therefore that would know the cause of Cold must find by what motion or motions the exterior parts of any Body endeavour to retire inwards To begin with those Phaenomena which are the most familiar There is almost no man but knows that breath blown strongly and which comes from the mouth with violence that is to say the passage being straight will Cool the hand and that the same breath blown gently that is to say through a greater aperture wil warm the same The cause of which Phaenomenon may be this The breath going out hath two motiōs the one of the whole and direct by which the formost parts of the hand are driven inwards the other simple motion of the small particles of the same breath which as I have shewn in the 3d Article of the last Chapter causeth Heat According therefore as either of these Motions is predominant so there is the sense sometimes of Cold sometimes of Heat Wherefore when the breath is softly breathed out at a large passage that simple Motion which causeth Heat prevaileth and consequently Heat is felt and when by compressing the lips the breath is more strongly blown out then is the direct motion prevalent which makes us feel Cold. For the direct motion of the breath or aire is Wind and all Wind Cools or diminisheth former heat 2 And seeing not onely great Wind but almost any Ventilation and stirring of the Aire doth refrigerate the reason of many experiments concerning Cold cannot well be given without finding first what are the causes of Wind. Now Wind is nothing else but the direct motion of the Aire thrust forwards which nevertheless when many Winds concurre may be circular or otherwise indirect as it is in Whirle-winds Wherefore in the first place we are to enquire into the Causes of Winds Wind is Aire moved in a considerable quantity and that either in the manner of Waves which is both forwards also up down or else forwards onely Supposing therefore the Aire both cleer and calm for any time how little soever yet the greater Bodies of the World being so disposed and ordered as has been said it will be necessary that a Wind presently arise some where For seeing that motion of the parts of the Aire which is made by the Simple Motion of the Sunne in his own Epicycle causeth an exhalation of the particles of water from the Seas and all other moist Bodies and those particles make Clouds it must needs follow that whilest the particles of water pass upwards the particles of Aire for the keeping of all Spaces full be justled out on every side and urge the next particles and these the next till having made their circuit there comes continually so much Aire to the hinder parts of the Earth as there went water from before it Wherefore the ascending Vapours move the Aire towards the sides every way and all direct motion of the Aire being Wind they make a Wind. And if this Wind meet often with other Vapours which arise in other places it is manifest that the force thereof will be augmented the way or course of it changed Besides according as the Earth by its diurnal motion turns sometimes the drier sometimes the moister part towards the Sunne so sometimes a greater sometimes a less quantity of Vapours will be raised that is to say sometimes there will be a less sometimes a greater Wind. Wherefore I have rendred a possible cause of such Winds as are generated by Vapours and also of their Inconstancy From hence it follows that these Winds cannot be made in any place which is higher then that to which Vapours may ascend Nor is that incredible which is reported of the highest Mountains as the Pique of Tenariffe and the Andes of Peru namely that they are not at all troubled with these inconstant Winds And if it were certain that neither Rain nor Snow were ever seen in the highest tops of those Mountains it could not be doubted but that they are higher then any place to which Vapours use to ascend 3 Nevertheless there may be Wind there though not that which is made by the ascent of Vapours yet a less more constant Wind like the continued blast of a pair of bellows blowing from the East And this may have a double cause the one the diurnal mo tion of the Earth the other its simple motion in its own Epicycle For these Mountains being by reason of their height more eminent then all the rest of the parts of the Earth do by both these Motions drive the Aire from the West Eastwards To which though the diurnal Motion contribute but little yet seeing I have supposed that the simple Motion of the Earth in its own Epicycle makes two revolutions in the same time in which the diurnal Motion makes but one and that the Semidiameter of the Epicycle is double to the Semidiameter of the diurnal Conversion the Motion of every point of the Earth in its own Epicycle will have its velocity quadruple to that of the diurnal Motion so that by both these Motions together the tops of those Hils will sensibly be moved against the Aire and consequently a Wind will be felt For whether the Air strike the Sentient or the Sentient the Air the perception of Motion will be the same But this Wind seeing it is not caused by the ascent of Vapours must necessarily be very Constant. 4 When one Cloud is already ascended into the Aire if another Cloud ascend towards it that part of the Aire which is intercepted between them both must of necessity be pressed out every way Also when both of them whilest the one ascends and the other either stayes or descends come to be joyned in such manner as that the aethereal substance be shut within them on every side it will by this compression also go out by penetrating the Water
be done 16 Granting that the Clouds may be frozen it is no wonder if the Moon have been seen eclipsed at such time as she hath been almost two degrees above the Horizon the Sunne at the same time appearing in the Horizon for such an Eclipse was observed by Mestline at Tubing in the year 1590. For it might happen that a frozen Cloud was then interposed between the Sunne and the Eie of the Observer And if it were so the Sunne which was then almost two Degrees below the Horizon might appear to be in it by reason of the passing of his Beams through the Ice And it is to be noted that those that attribute such refractions to the Atmosphere cannot attribute to it so great a refraction as this Wherefore not the Atmosphere but either Water in a continued Body or else Ice must be the cause of that refraction 17 Again granting that there may be Ice in the Clouds it will be no longer a wonder that many Sunnes have sometimes appeared at once For Looking-glasses may be so placed as by reflections to shew the same object in many places And may not so many frozen Clouds serve for so many Looking-glasses and may they not be fitly disposed for that purpose Besides the number of Appearances may be encreased by refractions also and therefore it would be a greater wonder to me if such Phaenomena as these should never happen And were it not for that one Phaenomenon of the new Starre which was seen in Cassiopaea I should think Comets were made in the same manner namely by Vapours drawn not onely from the Earth but from the rest of the Planets also and congeled into one continued Body For I could very well from hence give a reason both of their Haire and of their motions But seeing that Starre remained sixteen whole moneths in the same place amongst the fixed Starres I cannot believe the matter of it was Ice Wherefore I leave to others the disquisition of the cause of Comets concerning which nothing that hath hitherto been published 〈…〉 the bare Histories of them is worth considering 18 The Heads of Rivers may be deduced from Rain-water or from melted Snowes very easily but from other causes very hardly or not at all For both Rain-water and melted Snowes run down the descents of Mountains and if they descend onely by the outward Superficies the Showres or Snowes themselves may be accounted the Springs or Fountains but if they enter the Earth descend within it then wheresoever they break out there are their Springs And as these Spings make small streams so many small streams running together make Rivers Now there was never any Spring foūd but where the Water w ch flowed to it was either further or at least as farre from the center of the Earth as the Spring it self And whereas it has bin objected by a great Philosopher that in the top of Mount-Cenis which parts Savoy from Piemont there Springs a River which runs down by Susa it is not true For there are above that River for two miles length very high hils on both sides which are almost perpetually covered with Snow from which innumerable little streams running down do manifestly supply that River with water sufficient for its magnitude CHAP. XXIX Of Sound Odour Savour and Touch 1 The definition of Sound and the distinctions of Sounds 2 The cause of the degrees of Sounds 3 The difference between Sounds Acute and Grave 4 The difference between Clear and Hoarse Sounds whence 5 The Sound of Thunder and of a Gunne whence it proceeds 6 Whence it is that Pipes by blowing into them have a clear Sound 7 Of Reflected Sound 8 From whence it is that Sound is Uniform and Lasting 9 How Sound may be helped aud hindered by the Wind. 10 Not onely Aire but other Bodies how hard soever they be conveigh Sound 11 The causes of Grave and Acute Sounds and of Concent 12 Phaenomena for Smelling 13 The first Organ and the generation of Smelling 14 How it is helped by Heat and by Wind. 15 Why such Bodies are least smelt which have least intermixture of Aire in them 16 Why Odorous things become more Odorous by being bruised 17 The first Organ of Tasting and why some Savours cause Nauseousness 18 The first Organ of Feeling and how we come to the knowledge of such Objects as are common to the Touch and other Senses SOUND is Sense generated by the action of the Medium when its motion reacheth the Eare and the rest of the Organs of Sense Now the motion of the Medium is not the Sound it self but the cause of it For the Phantasme which is made in us that is to say the Reaction of the Organ is properly that which we call Sound The principal distinctions of Sounds are these First that one Sound is stronger another Weaker Secondly that one is more Grave another more Acute Thirdly that one is Clear another Hoarse Fourthly that one is Primary another Derivative Fifthly that one is Uniform another not Sixthly that one is more Durable another less Durable Of all which distinctions the members may be subdistinguished into parts distinguishable almost infinitely For the variety of Sounds seems to be not much less then that of Colours As Vision so Hearing is generated by the motion of the Medium but not in the same manner For Sight is from Pressure that is from an Endeavour in which there is no perceptible progression of any of the parts of the Medium but one part urging or thrusting on an other propagateth that action successively to any distance whatsoever whereas the motion of the Medium by which Sound is made is a Stroke For when we Hear the Drumme of the Eare which is the first Organ of Hearing is stricken and the Drumme being stricken the Pia Mater is also shaken and with it the Arteries which are inserted into it by which the action being propagated to the Heart it self by the reaction of the Heart a Phantasm is made which we call Sound and because the reaction tendeth outwards we think it is without 2 And seeing the effects produced by Motion are greater or lesse not onely when the Velocity is greater or less but also when the Body hath greater or less Magnitude though the Velocity be the same a Sound may be greater or lesse both these wayes And because neither the greatest nor the least Magnitude or Velocity can be given it may happen that either the motion may be of so small velocity or the Body it self of so small magnitude as to produce no Sound at all or either of them may be so great as to take away the Faculty of Sense by hurting the Organ From hence may be deduced possible causes of the strength and weakness of Sounds in the following Phaenomena The first whereof is this That if a man speak through a Trunk which hath on end applyed to the mouth of the Speaker and the other to the eare of the
of the cause of Smels I shall make use of the evidence of these following Phaenomena First that Smelling is hindred by Cold and helped by Heat Secondly that when the Wind bloweth from the Object the Smel is the stronger and contrarily when it bloweth from the Sentient towards the Object the weaker both which Phaenomena are by experience manifestly found to be true in Doggs which follow the track of Beasts by the Sent. Thirdly that such Bodies as are less pervious to the fluid Medium yeild less Smell then such as are more pervious as may be seen in Stones and Metals which compared with Plants and Living Creatures and their Parts Fruits and Excretions have very little or no Smell at all Fourthly that such Bodies as are of their own nature Odorous become yet more Odorous when they are bruised Fifthly that when the breath is stopped at least in Men nothing can be Smelt Sixthly that the sense of Smelling is also taken away by the stopping of the Nostrils though the mouth be left open 13 By the fourth and fifth Phaenomenon it is manifest that the first and immediate Organ of Smelling is the innermost cuticle of the Nostrils and that part of it which is below the passage common to the Nostrils and the Palate For when we draw breath by the Nostrils we draw it into the Lungs That breath therefore which conveighs Smels is in the way which passeth to the Lungs that is to say in that part of the Nostrils which is below the passage through which the breath goeth For nothing is Smelt neither beyond the passage of the breath within nor at all without the Nostrils And seeing that from different Smels there must necessarily proceed some mutation in the Organ and all mutation is motion it is therefore also necessary that in Smelling the parts of the Organ that is to say of that internal cuticle and the nerves that are inserted into it must be diversly moved by different Smels And seeing also that it hath been demonstrated that nothing can be moved but by a Body that is already moved and contiguous and that there is no other Body contiguous to the internal membrane of the nostrils but breath that is to say attracted aire and such little solid invisible Bodies if there be any such as are intermingled with the aire it follows necessarily that the cause of Smelling is either the motion of that pure aire or aethereal Substance or the motion of those small Bodies But this motion is an effect proceding from the Object of Smell and therefore either the whole Object it self or its several parts must necessarily be moved Now we know that Odorous Bodies make Odour though their whole bulk be not moved Wherefore the cause of Odour is the motion of the invisible parts of the Odorous Body And these invisible parts do either go out of the Object or else retaining their former situation with the rest of the parts are moved together with them that is to say they have simple and invisible motion They that say there goes something out of the Odorous Body call it an Effluvium which Effluvium is either of the aethereal substance or of the small Bodies that are intermingled with it But that all variety of Odours should proceed from the Effluviums of those small Bodies that are intermingled with the aethereal substance is altogether incredible for these considerations First that certain Unguents though very little in quantity do nevertheless send forth very strong Odours not onely to a great distance of place but also to a great continuance of time and are to be Smelt in every point both of that place and time so that the parts issued out are sufficient to fil ten thousand times more space then the whole Odorous Body is able to fill which is impossible Secondly that whether that issuing out be with straight or with crooked motion if the same quantity should flow from any other Odorous Body with the same motion it would follow that all Odorous Bodies would yeild the same Smell Thirdly that seeing those Effluviums have great Velocity of motion as is manifest from this that noysome Odours proceeding from caverns are presently Smelt at a great distance it would follow that by reason there is nothing to hinder the passage of those Effluviums to the Organ such motion alone were sufficient to cause Smelling Which is not so for we cannot Smell at all unless we draw in our breath through our Nostrils Smelling therefore is not caused by the Effluvium of Atomes nor for the same reason is it caused by the Effluvium of aethereal substance for so also we should Smell without the drawing in of our breath Besides the aethereal substance being the same in all Odorous Bodies they would always affect the Organ in the same manner and consequently the Odours of all things would be like It remains therefore that the cause of Smelling must consist in the Simple motion of the parts of Odorous Bodies without any efflux or diminution of their whole substance And by this motion there is propagated to the Organ by the intermediate aire the like motion but not strong enough to excite Sense of it self without the attraction of aire by respiration And this is a possible cause of Smelling 14 The cause why Smelling is hindred by Cold and helped by Heat may be this that Heat as hath been shewn in the 21 Chapter generateth Simple motion and therefore also wheresoever it is already there it will encrease it and the cause of Smelling being encreased the Smell it self will also be encreased As for the cause why the Wind blowing from the Object makes the Smell the stronger it is all one with that for which the attraction of aire in respiration doth the same For he that draws in the aire next to him draws with it by succession that aire in which is the Object Now this motion of the aire is Wind and when another Wind bloweth from the Object will be encreased by it 15 That Bodies which cōtain the least quantity of air as Stones and Metals yeild less Smell then Plants and Living Creatures the cause may be that the motion which causeth Smelling is a motion of the fluid parts onely which parts if they have any motion from the hard parts in which they are contained they communicate the same to the open aire by which it is propagated to the Organ Where therefore there are no fluid parts as in Metals or where the fluid parts receive no motion from the hard parts as in Stones which are made hard by accretion there can be no Smell And therefore also the Water whose parts have little or no motion yeildeth no Smell But if the same Water by Seeds and the heat of the Sunne be together with particles of Earth raised into a Plant and be afterwards pressed out again it will be Odorous as Wine from the Vine And as Water passing through plants is by the motion
of the parts of those plants made an Odorous liquour so also of aire passing through the same plants whilest they are growing are made Odorous aires And thus also it is with the Juices and Spirits which are bred in Living Creatures 16 That Odorous Bodies may be made more Odorous by Contrition proceeds from this that being broken into many parts which are all Odorous the aire which by respiration is drawn from the Object towards the Organ doth in its passage touch upon all those parts and receives their motion Now the aire toucheth the superficies onely and a Body having less superficies whilest it is whole then all its parts together have after it is reduced to powder it follows that the same Odorous Body yeildeth less Smell whilest it is whole then it will do after it is broken into smaller parts And thus much of Smels 17 The Tast follows whose generation hath this difference from that of the Sight Hearing and Smelling that by these we have Sense of remote Objects whereas we Tast nothing but what is contiguous and doth immediately touch either the Tongue or Palate or both From whence it is evident that the cuticles of the Tongue and Palate and the Nerves inserted into them are the first Organ of Tast and because from the concussion of the parts of these there followeth necessarily a concussion of the Pia Mater that the action communicated to these is propagated to the Brain and from thence to the farthest Organ namely the Heart in whose reaction consisteth the nature of Sense Now that Savours as well as Odours doe not onely move the Brain but the Stomack also as is manifest by the loathings that are caused by them both they that consider the Organ of both these Senses will not wonder at all seeing the Tongue the Palate the Nostrils have one and the same continued cuticle derived from the Dura Mater And that Effluviums have nothing to doe in the Sense of Tasting is manifest from this that there is no Tast where the Organ and the Object are not contiguous By what variety of motions the different kinds of Tasts which are innumerable may be distinguished I know not I might with others derive them from the divers figures of those Atomes of which whatsoever may be Tasted consisteth or from the diverse motions which I might by way of Supposition attribute to those Atomes conjecturing not without some likelyhood of truth that such things as tast Sweet have their particles moved with slow circular motion and their figures Spherical which makes them smooth and pleasing to the Organ that Bitter things have circular motion but vehement and their figures full of Angles by which they trouble the Organ and that Sowre things have straight and reciprocal motion and their figures long and small so that they cut and wound the Organ And in like manner I might assigne for the causes of other Tasts such several motions and figures of Atomes as might in probability seem to be the true causes But this would be to revolt from Philosophy to Divination 18 By the Touch we feel what Bodies are Cold or Hot though they be distant from us Others as Hard Soft Rough and Smooth we cannot feel unless they be contiguous The Organ of Touch is every one of those membranes which being continued from the Pia Mater are so diffused throughout the whole Body as that no part of it can be pressed but the Pia Mater is pressed together with it Whatsoever therefore presseth it is felt as Hard or Soft that is to say as more or less Hard. And as for the Sense of Rough it is nothing else but innumerable perceptions of Hard and Hard succeeding one another by short intervals both of time and place For we take notice of Rough and Smooth as also of Magnitude and Figure not onely by the Touch but also by Memory For though some things are touched in one Point yet Rough and Smooth like Quantity and Figure are not perceived but by the Flux of a Point that is to say we have no Sense of them without Time and we can have no Sense of Time without Memory CHAP. XXX Of Gravity 1 A Thick Body doth not contain more Matter unless also more Place then a Thinne 2 That the Descent of Heavy Bodies proceeds not from their own Appetite but from some Power of the Earth 3 The difference of Gravities proceedeth from the difference of the Impetus with which the Elements whereof Heavy Bodies are made do fall vpon the Earth 4 The cause of the Descent of Heavy Bodies 5 In what proportion the Descent of Heavy Bodies is accelerated 6 Why those that Dive do not when they are under Water feel the waight of the Water above them 7 The Waight of a Body that floateth is equal to the Waight of so much Water as would fill the space which the immersed part of the Body takes up within the Water 8 If a Body be Lighter then Water then how big soever that Body be it will float upon any quantity of Water how little soever 9 How Water may be lifted up and forced out of a Vessel by Air. 10 Why a Bladder is Heavier when blown full of aire then when it is empty 11 The cause of the ejection upwards of Heavy Bodies from a Wind-Gun 12 The cause of the ascent of Water in a Weather-glass 13 The cause of motion upwards in Living Creatures 14 That there is in Nature a kind of Body Heavier then Aire which nevertheless is not by Sense distinguishable from it 15 Of the cause of Magnetical vertue 1 IN the 21 Chapter I have defined Thick and Thinne as that place required so as that by Thick was signified a more Resisting Body and by Thinne a Body less Resisting following the custome of those that have before me discoursed of Refraction Now if we consider the true and vulgar signification of those words we shall find them to be Names Collective that is to say Names of Multitude as Thick to be that which takes up more parts of a space given Thinne that which contains fewer parts of the same magnitude in the same space or in a space equal to it Thick therefore is the same with Frequent as a Thick Troop And Thinne the same with Unfrequent as a Thinne Rank Thinne of Houses not that there is more matter in one place then in another equal place but a greater quantity of some named Body For there is not less matter or Body indefinitely taken in a Desert then there is in a City but fewer Houses or fewer Men. Nor is there in a Thick Rank a greater quantity of Body but a greater number of Souldiers then in a Thinne Wherefore the multitude paucity of the parts contained within the same space do constitute Density and Rarity whether those parts be separated by Vacuum or by Aire But the consideration of this is not of any great moment in Philosophy and therefore I let
to be setled any where as at H. If now the heat of the aire be augmented the water will descend below H and if the heat be diminished it will ascend above it Which though it be certainely known to be true by experience the cause neverthelesse hath not as yet been discovered In the 6 and 7 articles of the 27th chapter where I consider the cause of Cold I have shewne that fluid Bodies are made colder by the pressure of the aire that is to say by a constant Wind that presseth them For the same cause it is that the Superficies of the water is pressed at F and having no place to which it may retire from this pressure besides the cavity of the Cylinder between H and E it is therefore necessarily forced thither by the Cold and consequently it ascendeth more or lesse according as the Cold is more or lesse encreased And againe as the Heat is more intense or the Cold more remisse the same water will be depressed more or lesse by its own Gravity that is to say by the cause of Gravity above explicated 13 Also Living creatures though they be Heavy can by Leaping Swimming Flying raise themselvs to a certain degree of height But they cannot do this except they be supported by some resisting Body as the Earth the Water and the Aire For these motions have their beginning from the contraction by the helpe of the Muscles of the Body animate For to this contraction there succeedeth a distension of their whole Bodies by which distension the Earth the Water or the Aire which supporteth them is pressed and from hence by the reaction of those pressed Bodies Living Creatures acquire an endeavour upwards but such as by reason of the Gravity of their Bodies is presently lost againe By this endeavour therefore it is that Living creatures rayse themselues up a little way by Leaping but to no great purpose but by Swimming Flying they raise themselves to a greater height because before the effect of their endeavour is quite extinguished by the Gravity of their bodies they can renew the same endeavour againe That by the power of the Soule without any antecedent contraction of the Muscles or the helpe of something to support him any man can be able to raise his Body upwards is a childish conceipt For if it were true a man might raise himselfe to what height he pleased 14 The diaphanous Medium which surrounds the Eie on all fides is invisible Nor is Aire to be seen in Aire nor Water in Water nor any thing but that which is more opacous But in the confines of two diaphanous Bodies one of them may be distinguished from the other It is not therefore a thing so very ridiculous for ordinary people to think all that Space empty in which we say is Aire it being the worke of Reason to make us conceive that the Aire is any thing For by which of our Senses is it that we take notice of the Aire seeing we neither See nor Hear nor Tast nor Smell nor Feel it to be any thing When we feel Heat we do not impute it to the Air but to the Fire nor do we say the aire is Cold but we our selves are Cold and when we feel the Wind we rather think something is comming then that any thing is already come Also we do not at al feel the waight of water in water much less of air in air That we come to know that to be a Body which we call Aire it is by Reasoning but it is from one Reason onely namely because it is impossible for remote Bodies to work upon our Organs of Sense but by the help of Bodies intermediate without which we could have no sense of them till they came to be contiguous Wherefore from the Senses alone without reasoning from effects we cannot have sufficient evidence of the nature of Bodies For there is under-ground in some Mines of Coles a certain matter of a middle nature between Water and Aire which nevertheless cannot by Sense be distinguished from aire for it is as Diaphanous as the purest aire and as farre as Sense can judge equally penetrable But if we look upon the effect it is like that of water For when that matter breaks out of the Earth into one of those Pits it fils the same either totally or to some degree and if a Man or Fire be then let down into it it extinguishes them in almost as little time as water would do But for the better understanding of this Phaenomenon I shall describe the 6th figure In which let A B represent the pit of the Mine and let part thereof namely C B be supposed to be filled with that matter If now a lighted Cādle be let down into it below C it wil as suddenly be extinguished as if it were thrust into water Also if a grate filled with coles throughly kindled and burning never so brightly be let down as soon as ever it is below C the fire will begin to grow pale and shortly after losing its light be extinguished no otherwise then if it were quenched in water But if the grate be drawn up again presently whilest the coles are still very hot the fire will by little and little be kindled again and shine as before There is indeed between this matter water this considerable difference that it neither wetteth nor sticketh to such things as are put down into it as water doth which by the moisture it leaveth hindereth the kindling again of the matter once extinguished In like manner if a Man be let down below C he will presently fall into a great difficulty of breathing and immediately after into a swoun and die unless he be suddenly drawn up again They therefore that go down into these pits have this custome that as soon as ever they feel themselves sick they shake the rope by which they were let down to signifie they are not well and to the end that they may speedily be pulled up again For if a man be drawn out too late void of sense and motion they digg up a Turff and put his face and mouth into the fresh earth by which means unless he be quite dead he comes to himself again by little and little and recovers life by the breathing out as it were of that suffocating matter which he had sucked in whilest he was in the pit almost in the same manner as they that are drowned come to themselves again by vomiting up the water But this doth not happen in all Mines but in some onely and in those not alwayes but often In such Pits as are subject to it they use this remedy They dig another pit as DE close by it of equal depth and joyning them both together with one common channel EF they make a Fire in the bottom E which carries out at D the aire contained in the pit DE and this draws with it the aire contained in the channel EF which
in like manner is followed by the noxious matter contained in CB by this means the pit is for that time made healthful Out of this History which I write onely to such as have had experience of the truth of it without any designe to support my Philosophy with Stories of doubtful credit may be collected the following possible cause of this Phaenomenon namely that there is a certain matter fluid most transparent and not much lighter then water which breaking out of the Earth fills the Pit to C and that in this matter as in water both Fire and Living creatures are extinguished 15 About the nature of Heavy Bodies the greatest difficulty ariseth from the contemplation of those things which make other Heavy Bodies ascend to them such are Jet Amber and the Loadstone But that which troubles men most is the Loadstone which is also called Lapis Herculeus a stone though otherwise despicable yet of so great power that it taketh up Iron from the Earth and holds it suspended in the aire as Hercules did Antaeus Nevertheless we wonder at it somewhat the less because we see Jet draw up Straws which are Heavy Bodies though not so Heavy as Iron But as for Jet it must first be excited by rubbing that is to say by motion to and fro whereas the Loadstone hath sufficient excitation from its own nature that is to say from some internal principle of motion peculiar to it self Now whatsoever is moved is moved by some contiguous and moved Body as hath been formerly demonstrated And from hence it follows evidently that the first endeavour which Iron hath towards the Loadstone is caused by the motion of that aire which is contiguous to the Iron Also that this motion is generated by the motion of the next aire and so on successively till by this succession we find that the motion of all the intermediate air taketh its beginning from some motion which is in the Loadstone it self which motion because the Loadstone seems to be at rest is invisible It is therefore certain that the attractive power of the Loadstone is nothing else but some motiō of the smallest particles thereof Supposing therefore that those small Bodies of which the Loadstone is in the bowels of the Earth composed have by nature such motion or endeavour as was above attributed to Jet namely a reciprocal motiō in a line too short to be seen both those stones wil have one the same cause of attraction Now in what manner and in what order of working this cause produceth the effect of attraction is the thing to be enquired And first we know that when the string of a Lute or Viol is stricken the Vibration that is the reciprocal motion of that string in the same straight Line causeth like Vibration in another string which has like tension We know also that the dregs or small sands which sink to the bottom of a Vessel will be raised up from the bottom by any strong and reciprocal agitation of the water stirred with the hand or with a staff Why therefore should not reciprocal motion of the parts of the Loadstone contribute as much towards the moving of Iron For if in the Loadstone there be supposed such reciprocal motion or motion of the parts forwards and backwards it will follow that the like motion will be propagated by the aire to the Iron and consequently that there will be in all the parts of the Iron the same reciprocations or motions forwards and backwards And from hence also it will follow that the intermediate aire between the Stone and the Iron will by little and little be thrust away and the aire being thrust away the Bodies of the Loadstone and the Iron will necessarily come together The possible cause therefore why the Loadstone and Jet draw to them the one Iron the other Strawes may be this that those attracting Bodies have reciprocal motion either in a straight line or in an Elliptical line when there is nothing in the nature of the attracted Bodies which is repugnant to such a motion But why the Loadstone if with the help of Cork it float at liberty upon the top of the water should from any position whatsoever so place it self in the plain of the Meridian as that the same points which at one time of its being at rest respect the Poles of the Earth should at all other times respect the same Poles the cause may be this That the reciprocal motion which I supposed to be in the parts of the Stone is made in a line parallel to the Axis of the Earth and has been in those parts ever since the Stone was generated Seeing therefore the Stone whilest it remains in the Mine and is carried about together with the Earth by its diurnal motion doth by length of time get a habit of being moved in a line which is perpendicular to the line of its reciprocal motion it will afterwards though its axis be removed from the parallel situation it had with the axis of the Earth retain its endeavour of returning to that situation again and all endeavour being the beginning of motion and nothing intervening that may hinder the same the Loadstone will therefore return to its former situation For any piece of Iron that has for a long time rested in the plain of the Meridian whensoever it is forced from that situation and afterwards left to its own liberty again will of it self return to lie in the Meridian again which return is caused by the endeavour it acquired from the diurnal motion of the Earth in the parallel circles which are perpendicular to the Meridians If Iron be rubbed by the Loadstone drawn from one Pole to the other two things will happen one that the Iron will acquire the same direction with the Loadstone that is to say that it will lie in the Meridian and have its Axis and Poles in the same position with those of the Stone the other that the like Poles of the Stone and of the Iron will avoid one another and the unlike Poles approach one another And the cause of the former may be this that Iron being touched by motion which is not reciprocal but drawn the same way from Pole to Pole there will be imprinted in the Iron also an endeavour from the same Pole to the same Pole For seeing the Loadstone differs from Iron no otherwise then as Ore from Metal there will be no repugnance at all in the Iron to receive the same motion which is in the Stone From whence it follows that seeing they are both affected alike by the diurnal motion of the Earth they will both equally return to their situation in the Meridian whensoever they are put frō the same Also of the later this may be the cause that as the Loadstone in touching the Irō doth by its action imprint in the Iron an endeavour towards one of the Poles suppose towards the North Pole so reciprocally the