Munday,Septemb.9. 1666.
Observations made in several places (atLondon,MadridandParis,) of the lateEclipse of the Sun, which hapnedJune22. 1666. Some Enquiries and Directions, concerningTides, proposed byDr. Wallis. Considerations and Enquiries touching the same Argument, suggested by SirRobert Moray. An Account of several Books lately publish't: Vid. 1.Johannis Hevelii Descriptio Cometæ,A. 1665. exorti; una cumMantissa Prodromi Cometici. 2.Isaacus Vossius de Nili & aliorum Fluminum Origine. 3.Le Discernement du Corps & de l'Ame, par Monsieur deCordemoy.
Observations made in several places (atLondon,MadridandParis,) of the lateEclipse of the Sun, which hapnedJune22. 1666. Some Enquiries and Directions, concerningTides, proposed byDr. Wallis. Considerations and Enquiries touching the same Argument, suggested by SirRobert Moray. An Account of several Books lately publish't: Vid. 1.Johannis Hevelii Descriptio Cometæ,A. 1665. exorti; una cumMantissa Prodromi Cometici. 2.Isaacus Vossius de Nili & aliorum Fluminum Origine. 3.Le Discernement du Corps & de l'Ame, par Monsieur deCordemoy.
The Observations that were made atLondonby Mr.Willughby, Dr.Pope, Mr.Hook, and Mr.Philips, are these:
ItsDurationhence appears to have been one hour and 54 m. Itsgreatest Obscuritysomewhat more than 7. digits. About the middle, between the Perpendicular and Westward HorizontalRadiusthe Sun, viewing it through Mr.Boyle's 60. foot-Telescope, there was perceived a little of the Limb of the Moon without the Diske of the Sun: which seemed to some of the Observers to come from some shiningAtmosphereabout the Body either of the Sun or Moon.
They affirm to have observ'd theFigureof thisEclipse, and measured theDigits, by casting theFigurethrough a 5 footTelescope, on an extended paper, fix't at a certain distance from the Eye-glasse, and having a round figure; all whoseDiameterswere divided, by 6ConcentrickCircles, into 12Digits.
The Observations made atMadridby a Noble Member of theRoyal Society, His Excellence the Earle ofSandwich, as they were sent to the Right Honourable, the Lord Vice-CountBrounker, are these;
The EclipsebeganatMadridabout 5 of the Clock in the morning, at 5 h. 15′, the SunsAltitudewas 6 deg. 55′.
TheMiddleof it was at 6 h. 2′, the SunsAltitude, 15. deg. 5′.
TheEndwas exactly at 7 h. 5′; the SunsAltitude, 25. deg. 24′.
TheDuration, 2h. 4′.
37. Parts of the Suns diameter remained light.
63. Parts of the same were darkened.
The Observations made atParisby MonsieurPayen, assisted by severalAstronomers, as they were printed inFrench, and addressed to Monsieur deMontmor, are these;
TheEclipsebegan there, at 5 h. 44′. 52″.mane. It ended at 7 h. 43′. 6″. So that itswhole Durationwas 1 h. 58′. 14″. Thegreatest Obscurationthey assign to have been 7. dig. 50. m. but they adde, that it seem'd to have been greater by 3 minuts; which M.Payenimputes to a particular motion oflibrationof the Suns Globe, which entertain'd that Luminary in the samePhasisfor the space of 8.min.and someseconds, as if it had been stopped in the midst of its Course; rather than to a tremulous Motion of theAtmosphere, asScheinerwould have it.
They intimate that they took the time of eachPhasisfrom halfdigitto halfdigit, as well by aPendulum, as by theAltitudesof theSuns Centerabove theHorizon, corrected by theVerticall ParalaxesandÆstivall Refractions, by which they judged, that though the Time by thePendulummay be sufficient forMechanicallOperations, yet 'tis not exact enough for establishing theGrounds of true Astronomy.
They further conceive that the apparentDiameterswere almost equal; seeing that in thePhasisof 6.Digits, theCircumferenceof theMoons diskpassed through theCenterof that of theSun, so as that two Lines drawn through the twoHornsof the Sun, made with theCommon Semi-diametertwoEquilateral Triangles.
Next, they affirm, That there was so great a Variation in theParallaxes, by reason as well of the Refractions of the Air, which environs the Earth, as of the Alteration of the Air, which encompasses the Moon, that theHornsof the Sun, there formed by the Shaddow of the Moon, appeared in all kinds ofFigures; Sometimes inclined to theVertical, sometimesPerpendicularto theHorizon, and at lastParallel; theConvexepart respecting theHeaven, and theConcave, theHorizon. By the crossing (so they go on) of theHornswith theAngles of Inclination, it will be easie to those, that have exactly observed them, and that are skill'd in the higherAstronomicalCalculations, to compute thetrue Placeof theMoonin herOrbite, that so it may be compared with that of theTables, and with that, which has been observ'd in other places, for the more precise determinating of theDifferenceofMeridians(that being the way, esteem'd byKeplerthe most certain) and for making a good Judgment of the defect or exactnesse of the CelestialTables.
Then they observe, That theBeginningand theMiddleof thisEclipsehapned to be in theNorth Eastern Hemisphere, and theEnd, in theSouth-Eastern. Thefirst Contact(as 'twere) of the two Disks was observ'd in theSuperior Limbof theSuns Diskin respect to theVertical Line, and in theInferiorin respect to theEcliptick: But theMiddle, and theEndwere seen in theSuperior Limb, in respect both to theVerticaland theEcliptick: And (what to this Author seems extraordinary) both theBeginningand theEndof thisEclipsehapned to be in theOrientalpart of the Suns Disk.
Lastly, they take notice, that by their Observations it appears, that there is but little exactness in all theAstronomical Tables, predicting theQuantity,BeginningandDurationof this Eclipse; Those ofLansbergiusimporting, That the Obscuration should be of 10. dig. 48′; those ofRicciolo, of 9. dig. 1′; and those ofKepler, of 7. dig. 30′. 16″: Again, that theDurationshould be of 2h. 2′. Lastly, TheBeginningdid anticipate theRicciolan Tablesby 5minuts, theEndby 23; and theMiddle, almost by 11. In the mean time the Author notes, that theRudolphin Tablescome nearest to the Truth; and withal assures theReaderof the goodnesse of theInstrumentsemployed in hisObservations, and of the singular care, he, together with his skilful Assistants, took in making them.
The Inquisitive Dr.Wallis, having in his lately printedHypothesisof Tides intimated, that he had reason to believe, that theAnnual Spring-tideshappen to be rather about the beginnings ofFebr.andNov.than the twoÆquinoxes, doth in a late Letter to thePublisher, written fromOxfordinAug.last, desire,thatsome understanding Persons atLondon, orGreenwich, but rather nearer theSea,or upon the Sea-shore, would makeparticularObservation of all theSpring-Tides(New-MoonandFull-Moon) between this and the End ofNovember; and take account of theHour, and of thePerpendicular height: that we may see, whether those inSeptember, or those ofNovemberbe highest: And it were not amiss, the Low waters were observed too. Which may be easily done by a mark made upon any standing Post in the Water, by anyWater-man, or other understanding Person, who dwells by the Water-side.
It would also deserve (thinks he) to be inquired into, whether, when the Tides be highest, the Ebbs be ever lowest, &contra; (which is generally affirmed, and almost put out of question) or rather (which sutes best with thisHypothesis) whether, when the Tides are highest, both in theAnnualandMenstrualPeriods, the Low waters be not also highest; and at Neap Tides, the Ebbes also very low.
He adds, that he should expect, that the Spring Tides now coming, and those at the beginning ofSeptember, should not be so high, as those at themiddleofSeptember; and then lower again at thebeginningofOctober, and after that, higher at themiddleofOctober, and higher yet about thebeginningofNovember(at the usual times ofSpring-tidesafter theNewandFull.)
In regard that the High and Low waters are observed to increase, and decrease regularly at several seasons, according to the Moons age, so as, about theNewandFull Moon, or within two or three daies after, in the Western parts ofEurope, theTidesare at thehighest, and about theQuarter-Moons, at thelowest, (the former call'dSpring-tides, the otherNeap-tides;) and that according to the height and excesses of theTides, theEbbesin opposition are answerable to them, the heighest Tide having the lowest Ebbe, and the lowest Ebbe, the highest Tide; the Tides from theQuarterto thehighest Spring-tideincreasing in a certain proportion; and from theSpring tideto theQuarter-tidedecreasing in like proportion, as is supposed: And also theEbbesrising and falling constantly after the same manner: It is wished, that it may be inquired, in what proportion these Increases and Decreases, Risings and Fallings happen to be in regard of one another?
And 'tis supposed, upon some Observations, made in fit places, by the above-mentioned Gentleman, though, (as himself acknowledges) not thoroughly and exactly performed, that the Increase of the Tides is made in theProportionofSines; the first Increase exceeding the lowest in a small proportion; the next in a greater; the third greater than that; and so on to the mid-most, whereof the excess is greatest, diminishing again from that, to the highest Spring-Tide; so as the proportions, before and after theMiddle, do greatly answer one another, or seem to do so. And likewise, from thehighest Spring-tide, to thelowest Neap-tide, theDecreasesseem to keep the like proportions; theEbbesrising and falling in like manner and in like proportions. All which is supposed to fall out, when no Wind or other Accident causes an alteration.
And whereas 'tis observed, that upon the main Sea-shore the Current of the Ebbings and Flowings is sometimes swifter, and sometimes slacker, than at others, so as in the beginning of the Floud the Tide moves faster but in a small degree, increasing its swiftness constantly till towards theMiddleof the Floud; and then decreasing in velocity again from theMiddletill to the top of the High water; it is supposed, that in Equal spaces of Time, the Increase and Decrease of velocity, and consequently the degrees of the Risings and Fallings of the same, in Equal spaces of time, are performed according to theProportionofSines.
But 'tis withall conceived, that the saidProportioncannot holdexactlyandprecisely, in regard of theInequalities, that fall out in thePeriodsof theTides, which are commonly observed and believed to follow certainPositionsof theMoonin regard of theEquinox, which are known not to keep apreciseandconstantCourse: so that, there not intervening equal portions of Time between one New Moon and another, the Moons return to the sameMeridian, cannot be alwaies perform'd in the same Time; and consequently there must be a like Variation of the Tides in the Velocity, and in the Risings and Fallings of the Tides, as to equal spaces of time. And the Tides from New-moon to New-moon being not alwaies the same in number, as sometimes but 57, sometimes 58, and sometimes 59, (without any certain order of succession) is another evidence of the difficulty of reducing this to any great exactness. Yet, because 'tis worth while, to learn as much of it, as may be, theProposerand many others do desire, That Observations be constantly made of all these Particulars for some Months, and, if it may be, years together. And because such Observations will be the more easily and exactly made, where the Tides rise highest, it is presumed, that a fitApparatusbeing made for the purpose, they may be made aboutBristolorCheap-stow, best of any places inEngland, because the Tides are said thereabout to rise to ten or twelve fathoms; as upon the coast ofBritannyinFrance, they do to thirteen and fourteen.
In order to which, this followingApparatusis proposed to be made use of. In some convenient place upon a Wall, Rock, or Bridge, &c. let there be anObservatorystanding, as neer as may be to the brink of the Sea, or upon some wall; and if it cannot be well placed just where the Low water is, there may be a Channel cut from the Low water to the bottom of the Wall, Rock, &c. The Observatory is to be raised above the High water 18. or 20. foot; and a Pump, of any reasonable dimension, placed perpendicularly by the Wall, reaching above the High water as high as conveniently may be. Upon the top of the Pump a Pulley is to be fastned, for letting down into the Pump a piece of floating wood, which, as the water comes in, may rise and fall with it. And because the rising and falling of the water amounts to 60. or 70. foot, the Counterpoise of the weight, that goes into the Pump, is to hang upon as many Pulleys, as may serve to make it rise & fall within the space, by which the height of the Pump exceeds the height of the Water. And because bythis means the Counterpoise will rise and fall slower; and consequently by less proportions, than the weight it self, the first Pulley may have upon it a Wheele or two, to turnIndexesat any proportion required, so as to give the minute parts of the motion, and degrees of risings and fallings. All which is to be observed byPendulum-watches, that haveMinutesandSeconds, withChecks, according to Mr.Hugens'sway.
And because if the Hole, by which the water is let into the Pump, be as large as the Bore of the Pump it self, the weight that is raised by the water, will rise and fall with an Undulalation, according to the inequality of the Sea's Surface, 'twill therefore be fit, that the Hole, by which the water enters, be less than half as bigg as the Bore of the Pump; any inconvenience that may follow thereupon, as to the Periods and Stations of the Floud and Ebb, not being considerable.
And to the end, that it may appear the better; what are theparticularObservations, desired to be made, nearBristolorCheap-stowbridg, it was thought not amiss, to set them down distinctly by themselves.
1. The degrees of the Rising and Falling of the water every quarter of an hour (or as often as conveniently may be) from the Periods of the Tides and Ebbs; to be observed night and day, for 2 or 3 months.
2. The degrees of the velocity of the Motion of the Water every quarter of an hour for some whole Tides together; to be observed by a secondPendul-watch: and a logg fastened to a line of some 50 fathoms, wound about a wheel.
3. The exact measures of the Heights of every utmost High-water and Low-water, from one Spring-tide to another, for some Months or rather Years.
4. The exact Heights of Spring-tides and Spring-Ebbs for some Years together.
5. The Position of the Wind at every observation of the Tides; and the times of its Changes; and the degrees of its Strength.
6. The State of the Weather, as to Rain, Hail, Mist, Haziness, &c, and the times of its Changes.
7. At the times of observation of the Tides, the height of theThermometer; the height of theBaroscope; the height of theHygroscope; the Age of the Moon, and herAzimuths; and her place in all respects; And lastly theSun'splace; all these tominutes.
And it would be convenient, to keepJournal Tables, for all these Observations, each answering to its day of the Month.
For theApparatusof all these observations, there will be particularly necessary.
A goodPendulum-watch.
AVaneshewingAzimuthsto minute parts.
AnIntrumentto measure the Strength of the Winde.
A large and goodneedleshewingAzimuthsto degrees.
Thermometers,Barometers,Hygroscopes.
These Observations being thought very considerable as well as curious, 'tis hoped, that those who have conveniency, will give encouragement and assistance for the making of them; and withall oblige the publick by imparting, what they shall have observed of this kind: ThePublisherintending, that when ever such observations shall be communicated to him, he will give notice of it to thepublick, and take care of the improvement thereof to the best use and advantage. APatternof theTable, proposed to be made for observing theTides, is intended to be published the next opportunity, God permitting.
I.Johannis Hevelii DESCRIPTIO COMETÆ, Anno Æræ Christianæ MDCLXV. exorti; unà cum MANTISSA Prodromi Cometici, Observationes omnes prioris COMETÆ MDCLIV, ex iisque genuinum motum accuratè deductum, cum Notis & Animadversionibus, exhibens.
This Book (as the Title it self intimates) undertakes two things.First, To give an Account of theSecondof the two late Comets, which appeared, when theotherwas scarce extinct; Concerning which, the Author doth, from the Observations made by himself with aSextantof 6 foot, and divided intominutesandseconds, assignbothits true place (as well in respect of theEcliptickas theÆquator)andits proper motion; Adding a fair Delineation of its Course, together with the genuine Representations of itsHeadandTrain, in each day of its apparition; and subjoyning a General Description and Discourse of some of the more notablePhenomenathereof. It was first seen atDantzickby the Watchmen, the 5th ofAprilst. n. 1665. and then observed by theAuthorfromApril6, about 1½ of the Clock in the morning, tillApril20 at 3. in the morning. During which time, it went with a reasonable velocity; making 46 deg. in its Orb,according to the Order of the Signs, moving from theBreastofPegasus, towards theHeadofAndromeda, and theLeft HornofAries; having, as 'tis presumed, taken its rise from aboveSagittary, and run through theBreastofAntinous, underAquilaand theDolphin, to the saidPegasus; and so on, as is already expressed.
TheHeadof it is in the Book described of a Colour like that ofJupiter, all along much brighter than that of the former Comet, though of a somewhat less magnitude; having in its middle onelyoneround, but very bright and bigKernelor Speck, resplendent like Gold, and encompassed with another more dilute and seemingly uniform matter: itsTailbeing at first, about 17. deg. and afterwards 20. and sometimes 25 deg. long, and divaricated towards the End.
Next, it is observed, that though this Star did afterwards slacken its pace, yet it retained the vividness of its Colour, both of theHeadandTrain; theHeadespecially, keeping at the time as well of the last observations, as of thefirst, the brightness of its singlekernel, though the environing more dilute matter were then almost all lost; it being, according to the Author, more and more attenuated, and grown narrow, the nearer the Star approached to the Sun.
Thirdly, 'tis noted, That thisCometdid very much digress from theHypothesis, delivered byM. Auzout, in regard that, whereas according to thatHypothesis, this Star should not arrive to theEclipticktill after the space of 3 months, it arrived there the 28 ofApril. And then, that its first Conjunction with the Sun hapned between the 19 and 20 ofApril, and the second, the last ofApril, not (asM. Auzout, would have it) the 15 ofMay. So that he concludes, that this Comet never came down to thePleiadsand theEye of Taurus, as the Hypothesis ofM. Auzoutrequires, but that fromApril20. it did immediately take its course towards the Ecliptick, deflecting every day more and more from theSectionof aGreat Circle, to theLucidaofAries, arriving at theEcliptickthe last ofApril, about the 8th or 10th deg. ofTaurus; not inJulyabout the 8th ofGemini, and theEye of Taurus.
Fourthly, He intimates, that if this Comet had appeared some weeks sooner, it would have confronted the former Comet, being yet in its vigour and of a conspicuous bigness, in the same place, where that was, viz. theHead of Aries.
Fifthly, He observes, that this Star in progress of time becameRetrograde, whence it came to pass, that in the Months ofJuneandJulyit did not appear again before the Rising of the Sun, though the Sun left it far behind: whereas, if it had proceeded toward theEye of Taurus, it would have appeared again in the morning.
Sixthly, He maintains, that this Comet was not the same with the former; which he thinks may be demonstrated, onely by a due Delineation of both their Course upon theGlobe; where he saith it to be evident, that the former could never come to theHeadofPegasus, as moving already inFebruaryin a streight Course about theHeadofAries; Besides, that theformerwent in the very beginning in aRetrogrademotion; butthisperpetually in a direct one:that, about the end, very slow, its Head lessning and growing dark;thisswift enough, with its head conspicuous and bright. To which he adds, that the whole Course of the former was made under a quite differentAngleof theOrbiteandEcliptick, and a different Motion of theNodesfrom the latter: As also that theirFacesdiffered very much from one another; thefirstexhibiting all along a matter, which as to its density and rarity, altered from day to day exceedingly, whereas thesecondretained (to the Authors admiration, who affirms, never to have observed the like) all the time he saw it, one and the same round, dense and bright Speck or Kernel.
All which he concludes 1, With an Intimation of his sense concerning two other Comets, pretended to have been lately seen,OneatRome, about theGirdle of Andromeda, in the Months ofFebruaryandMarch, 1664. the other inGermanyinCapricorne, aboutSaturnein the head ofSagittary, during the Months ofSeptemberandOctober, 1665. 2ly, With an Advertisement of what he has done in that important Work for the Advancement ofAstronomy, the dueRestitution of the Fixt Stars, vid.That he has almost finish't it; himself alone, without trusting to any other mans labour, that was not directed by him.
TheSecondPart of this Book (theMantissato theProdromus Cometicus) endeavours to justifie the Authors Observations touching the former Comet, excepted against by M.Auzout, in several particulars; as 1. That it had not pass'd to theFirst, butSecondStar inAries, and had mov'd in quite another Line, than He had described. 2. That itsproper motionabout the end ofJanuaryand the beginning ofFebruary, 1665. had not been rightly assigned. 3. That theBignesseof itsDiameterhad not been truly delivered; Nor 4. TheFacesof itsHeadin due manner represented.
To all which the Author endeavors to answer: 1. By delivering all his Observations of that Comet, thereby to shew, what care and diligence he had used,particularlyto make out, how great itsDiurnal motionhad been; in what proportion, and how far, it decreased, and where and in what degree it increased again: Which being, as he conceives, duly and exactly deduced, and demonstrated, he esteems it afterwards to be easie for every one, versed in these matters, certainly to collect and to judge, what way the Comet, after it became invisible to the naked Eye, and could be no longer observed withSextantsandQuadrants, had taken, and what Line it had described. 2, By subjecting all those Observations, with great diligence and labour, to a rigidCalculus, thereby to obtain, for every day, theLongitudes,Latitudes,Right Ascensions, Declinations,Proper motion,Angleof theEcliptickand theÆquator, and theNodesof that Comet; for the construction of anEphemeridesof its whole Motion. From all which he pretends to prove, that he has not erred in his Observation ofFebruary18, nor been prepossest by anyHypothesis, nor deluded by anyFixt Star, as M.Auzoutthinketh; but that near theFirst StarofAriestherethenappear'd aPhænomenon, most like to that Comet, that was seen some dayes before, if compared with the Observations make thereofFebr.12, 13, 14. Though he will not hitherto positively determine, whether thatPhænomenon, which appear'd to himFebruary18. wasindeed that very Comet, which he saw with his naked Eye, and observed with his Geometrical Instruments, the said 12, 13, and 14. dayes ofFebruary; or whether it was another, and whether he had lost that Comet, which moved towards theSecond StarinAries: but leaves it to the Learned World, and particularly to theRoyal Society, after they shall have well examined and considered all his Observations, and theCalculusraised therefrom, to judge of this, and the other particulars in controversie.
II.Isaacus Vossius de NILI et ALIORUM FLUMINUM ORIGINE. It wasNumb.14. of theseTransactions, that gave an account of theCauseof theInundation of the Nile, as it was rendred by Monsieurde la Chambre:Thisis to give you another, not only of theInundation, but also of theOrigineof that, and ofother Rivers, as it is delivered by MonsieurIsaac Vossius, who undertakes in this Book to shew;
1. That thoseSubterraneous Channels, through which severalPhilosophersteach, that the Sea discharges it self into the Rivers, are not only imaginary, but useless, in regard 'tis impossible for the water to rise from the Subterraneous places up to the Mountains, where commonly the Sources of Rivers are.
2. He explicates, why, if a Pipe be put into a Bason full of Water, the water is seen more raised in the Pipe, than in the Bason, and rises higher according as the Pipe is narrower; On the contrary, if the same Pipe be put into a Bason full of Quicksilver, the Quicksilver stayes lower in the Pipe, than in the Bason. The reason, which he renders hereof, is, That as the Water sticks easily to all it touches, it is sustain'd by the sides of the narrow Pipe wherein it is included: And indeed, if the Pipe be quite drawn out of the Water, the Water doth not all fall out, but so much of it remains, as the sides of the Pipe could sustaine: Whence it is, that the Water which is kept up by the Walls of the Tube, weighing no longer upon that which is in the Bason, is thrust upwards, and keeps it self raised above its Levell; but the Quicksilver not adhering so easily, as Water, to Bodies it touches, is not sustained by the sides of the Tube, and so mounts not above its Levell, but rather descends below it, because the Pipe, which is streight, hinders the endeavor that is in theMercuryto rise to its Level. He adds, that this Observation makes nothing for the Explication of theOrigine of Rivers; because, though it be true, that the Waterby this means rises above its Levell, yet it does never run out at the top of the Pipe. Having said this, he answers to the other Arguments, commonly alledged to maintain this Opinion.
3. He pretends, that all Rivers proceed from aColluviesorRendevousof Rain-waters, and that, as the Water, that falls uponHills, gathers more easily together, than that which falls inPlaines, therefore it is, that Rivers ordinarily take their Source fromHills. Thence also comes it (saies he) that there are moreRivers, thanTorrents, in theTemperate Zones; and, on the contrary, moreTorrents, thanRivers, in theTorrid Zone: For, as in hot Climats the Mountains are far higher, the Water, that descends from them with impetuosity, runs away in a little while, and formes such Collections of Water, as soon dry up, but in cold Climats, the Waters do not run away but slowly, and are renew'd and recruited by Rain, before they are quite dryed up; because the Hills are there lower, and so the Bed of Rivers hath lesse declivity.
Having thus discoursed ofRiversinGeneral, he treats of theNileinparticular; and there
1. Observes, That the Order of the Seasons of the Year is quite inverted under theTorrid Zone. For, whereas it should be then Summer, when the Sun is near; and Winter, when the Sun is farther off: Under theTorrid Zone'tis never lesse hot, than when the Sun is nearest; nor more hot, than when the Sun is farthest off: So that to the people that live between theÆquinoctialand theTropicks, Summer begins aboutChristmass, and their Winter, about St.Johnsday. The reason whereof is, (saith he) that when the Sun is directly over their Heads, it raises abundance of vapors, and draws them so high, that they are presently converted into Water by the coldnesse of the Air; whence it comes to passe, that then it rains continually, which does refresh the Air; but when the Sun is farther off, there falls no more rain, and so the Heat becomes insupportable.
2. He proves by many recent Relations, that theSourcesof theNileare on this side of theÆquinoctialinÆthiopia, of which he gives a very accurateMappe, correcting many faults whichGeographersare wont to commit in the Description of the Kingdom of theAbyssins, which they believe to be much greater than indeed it is.
3. This supposed, he easily gives an account, why theNileyearly overflows about the end ofJune: For, as at that time there falls much rain inÆthiopia, it must needs be, that theNile, whose source is in that Country, should then overflow, when those rains begin, and subside, when they cease.
There are besides, in this Book, two otherTracts. In thefirst, M.Vossinsendeavours to maintain the Doctrine, he had deliver'd in his BookDe Lumine, and to shew, that theSoulof Animals is nothing butFire, that there are no invisible Atoms; nor so much as any Pores, even in the Skin of man. Here he treats also ofRefractions, and alledges the Examples of several persons, who have then seen the Sun by the means of Refraction, when really He was under theHorizon.
In thesecond, He discourses of some points of theMechanicks; and relates among other things, that theArrowsandbattering Rams (Aries)of the Antients did as much execution, as ourMusketsandCanons; and then, that the Vehemence of the percussion depends as much upon the Length of the percutient Body, as upon the velocity of the Motion. He adds, that the Length of a Canon ought not to exceed 13 foot, and that a greater length is not onely useless, but hinders also the effect of the Gun, not because the Bullet is thrown out of the Gun, before all the powder is fired (as some believe;) but because the Bullet is then beaten back into the Gun by the Air, re-entring into it with impetuosity, when the flame is extinct.
III.LE DISCERNEMENT DU CORPS ET DE L'AME, par M.de Cordemoy.
ThisFrenchTreatise (but very lately come to thePublisher'shands) examines the different Operations of the Soul and Body, and the Secret of their Union, pretending to discover to every one, what he is, and what is transacting within him. It consists of six Discourses.
1. In thefirst, the Author examines the Notions, we have ingeneralofBodiesandMatter; ofQuantity; ofQualities; ofPlace; ofRest; ofMotion; ofVacuity; ofForms: to shew what is to be understood by these Terms, which cause all the perplexity that is in the ordinaryPhysicks. He begins with taking notice, that hithertoPhilosophershave had nodistinctnotions ofBodiesandMatter, from the want whereof he conceives, that almost all the Errors in CommonPhysiologyhave*It sounds hard, To say, Anextendedsubstance isindivisible.sprung. To rectify which, he definesBodiesto be *Extended Substances, andMatteranAggregate of Bodies. Whence he inferrs, thatBodiesare Indivisible andMatterdivisible; aBodybeing nothing butoneand thesamesubstance, whose different extremities are inseparable, because they are the extremities of one and the same Extension, and, in a word, of one and the same Substance; butMatterbeing nothing but an Association or Collection of Bodies, 'tis evident, (saith he) it must be divisible. This doctrine he so much insists upon, that he conceives, Nature cannot subsist, if a Body in the sence he takes it, be divisible; and thatMotionandRestcannot be explicated without it. As forQuantity, he makes that to be nothing but More or Less Bodies; not allowing, that each Body should be a Quantity, though it be a part of Quantity; no more than anUniteis a Number, though it make part of a Number: so thatQuantityandExtensionare two distinct things with him, thefirstbelonging properly toMatter, the last to aBody. TouchingVacuity, he conceives, that the Bodies, which compose a mass, are not every where so near one another, as not to leave some interval in several places. Neither does he think it necessary, that those intervals should be fill'd up; nor unconceivable, that there should be no Body between two Bodies; which touch not one another. And when 'tis said, that those intervals cannot be conceived without Extension, and that consequently there are Bodies that replenish them, he frankly pronounces that not to be true; and affirms, that though it may be said, that between two Bodies, which touch not one another, other Bodies may be placed of so or so many feet, &c: yet ought it not to be inferred, that therefore theyarethere, but onely, that they are thus placed, that theremaybe put between them so many Bodies, as joyned together would compose an Extension of so many feet. So that one conceives onely, that Bodiesmaybe placed there, but not that theyarethere: and as we can have anIdeaof many Bodies, though none of them be in being; so we can conceive, that some Bodiesmaybe put between others, where really there are none. And when 'tis alledged, that if all the Bodies, that fill a vessel full, were destroyed, the sides of the vessel would be closed together; He professes, he understands not that ratiocination, nor can conceive, what one Body does to the subsistence of another, more than to sustain themselves mutually, when they are thrust by the neighbouring ones: and therefore sees not, why the sides of the vessel should close, if nothing did thrust them together; but understands clearly, that two Bodies may well subsist so far from one another, that one might place a great many Bodies between them, or none at all, and yet they neither approach to, not recoil from one another.
2. In theSecond, he examines theChanges, which he knows in Matter, and makes it his business to explicate all those that respectQuantity,QualitiesandForms, byLocal Motion, esteeming that needs no other.
3. In thethird, he explains the Motion ofArtificialEngins, and that ofNaturalones, by one and the same Cause; endeavouring among other things to shew, that the Body of an Animal is moved after the same manner with a Watch. That cause of motion he makes theMateria Subtilis; and the finer or subtiler that is, the better and fitter he conceives it to be to preserve Motion.
4. In theFourth, he teaches, that though Experience seems to evince, that the Soul moves the Body, and that one Body moves an other; yet there is nothing but God, that can produce any notion in the World, and all other Agents, which we believe to be theCauseof this or that Motion, are no more but theOccasionthereof. In doing this, he advances certainAxioms, and Conclusions, which are in short,
a. TheAxioms: That no substance has that of it self, which it can loose, without ceasing to be, what it is: That every body may loose of its motion, till it have no more left, without ceasing to be a Body: That we cannot conceive but two sorts of substances,vid.aSpirit(orThat which thinketh) and aBody, wherefore they must be considered as the Causes of all, that happens, and what cannot proceed from the one, must necessarily be adscribed to the other: That toMove, or to cause motion, is an Action: That an Action cannot be continued but by the Agent, who began it.
b. TheConclusions: That noBodyhath Motion of it self: That the First Mover of Bodies not a Body: That it cannot be but aSpirit, that is the First Mover: That it cannot be but the same Spirit, who has begun to move Bodies, that continues to move.
In theFifth, He treats of the Union of the Body and Soul, and the manner, how they act one upon the other; and esteems it not more difficult to conceive the Action of Spirits upon Bodies, and of Bodies upon Spirits, than to conceive the Action of Bodies upon Bodies: the cause of the great difficulty in understanding the two former, arising (according to him) from thence, that we will conceive the one by the other, not considering, that every thing acting according to its own nature, we shall never know the action of one Agent, if we will examine it by the notions we have of another, that is of a quite differing nature. Here he notes, that the Action of Bodies upon Bodies is notmore known to us; than that of Spirits upon Bodies, or of Bodies upon Spirits; and yet most men admire nothing butthis, believing to know theother; whereas he Judges, that all things being well examin'd, the Action of Bodies upon Bodies is no more conceivable, than that of Spirits upon Bodies. Mean while the opinion of the Authour touching this subject, is, That the union of Soul and Body consists onely in this, that certain motions of the Body are followed by certainCogitationsof the Soul, and, on the contrary, that certain Thoughts of the Soul are follow'd by certainMotionsof the Body. And, having supposed, that Bodies are said to act upon one another, when they cause some change suitable to Extension; and Spirits to act upon one another, when they cause some change suitable to a Thought; he infers, that when a Body acts upon a Spirit, that cannot be by causing any change of motion, of figure, or parts, as having none of all these; nor when a Spirit acts upon a Body, that cannot be by producing any change of Thought, as having none: But, when this Body, or its motion, or figure, or other thing, depending upon its nature, can be perceived by a Spirit, so as, upon that occasion, this Spirit has thoughts, it had not before, it may be said, that the Body has acted upon this Spirit, for as much as it has caused all the change in it, whereof it was capable according to its nature.
In theSixth, After he hath shew'd, what is to be understood by what we callSoul, and by what we callBody, he labours to make it out, that we are much more assured of the Existence of the Soul, than of that of the Body, which he conceives he can prove from hence, that we cannot doubt, that we think, because even doubting is thinking; but one may doubt, whether one has a body, for several reasons, which he alledges, and thinks so cogent, that he concludes, it is not evident to him by the light of reason, that he has a Body. But supposing, there be Bodies, he examines, what are the Operations, that belong to the Soul, and what those, that belong to the Body; and lastly, what those, that result from the Union of both: And then explains, how all those operations are perform'd, and particularly,Sensation; where he shews, that the Nerves, holding at one end to the Brain, whereof they are but Allongations, and being at the other end extended to the extremities of the Body; when an Object comes to touch those exterior ends of the Nerves, the interior ones in the Brain are presently shaken; and cause different sensations according to the diversitie of Nerves, and the differing manner, in which they are shaken. And to shew, that 'tis this shaking, that causes Sensation, he notes, that if any thing shakes the interior parts of the Nerves, though the object be absent, the Soul has presently the samesensations, as it would have, if it were present. As, if one should knock on's head forcibly against a wall, the shaking, which the blow gives to the Brain, moving the interior extremities of the Nerve, which causes the sensation of Light, the Soul has the same sensation, which it would have, if it saw a thousand Candles: On the contrary, if the interior extremities of the nerves are not shaken, though the object be present, it causes no sensation; whence it comes, that if a strong Ligature be made upon the middle of the Arm, and the hand be then prickt, no pain is felt, because the shaking of the nerves that are pricked, being stopped by the Ligature, cannot reach to the extremities of the Nerves, that are within the Brain.
The followingErrata, left by thePressinNum.16, theReaderis desired thus to correct.
Page269. lin 27. read,motion of B above the Center; G. is also, with aSemi-colonafter the wordCenter. p.274. l. 13, r.it to do to the. p.277. l. 24. r.natural days. p.281. l. 16. r.of his. ib. l. 27. r.a notion. p.293. l. 4. r.enough without. ib. l. 43. r.to the Sine of. p.294. l. 1. r.to the Sine of.
Printed forJohn MartinandJames Alestry, Printers to the Royal Society. 1666.
Numb.18.