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~— Mifcelanea Curiofa. g CONT A INING A
COLLECTION
Of fome of the Principal
| PHENOMENA NATURE
Accounted for by the Greateft Phi- lofophers of this Age; BEING THE Moft Valuable Discourses, Read and
Delivered to the Royay Socirt x, for the Advancement of Phyfical and Ma- _ thematical Knowledge. » . As alfo a Collection of Curious Travels, Voyages,
Antiquities, and Natural Hiftories of Countries ; Prefented to the fame Society.
In Three VOLUMES. |
The Second Edition ; To which is added, A Difcourfe of the in- ye of the Sun and Moon on Hunawe Boties, &c. By » MEAD, M.D°F.R.S. And alfo Fontenelle’s Preface of te Ufefulnefs of Mathematical Learning. %
VO 1. a
LONDON:
SP riited by 7. M. for R. Smith, at the Bible under the core of the ‘a oe in Cornhill. 1708.
wih
oT O THE
$1
READER.
‘OM E of the Principal Dif y coveriesand Enquiries, both inPhyfical and. Mathematical Learn- ‘ing, being regifter’d in the Volu- minous Journals of the Royal Socie- ty, are: amongft a multitude of lefsufeful Matters, fo Obfcurely hid, that but very few inquifi- tive Gentlemen ever fo much as heard of them. © ‘The Defign therefore of the enfuing Collection, is to digeft _ ima convenient Method, all the moft curious Philofopbical kod Ma- thematical Difcoveries, as they are tobe met with, which may any way tend to the Ufe of Life or Ad- vancement of Arts and Sciences. wn i, ee And
The Preface.
And on this Occafion, it will be conventent to intimate to the Reader ;
First, That the Theories and - Difcourfes here colleGted, have already paft the Cenfure of the Learned World: Who have ac- knowleg’d them the moft fatis- fa€tory Accounts of Nature’s Pro- ceedings, wherein fome of her ereateft Depthsare fathom’d, and a Foundation laid for Pofterity to build an infinite Superftructure.
Secondly, That they are related (Verbatim) juft as they were delive-. red in, or read before the Royal Society: For it has been the Opi- nion of the moft Judicious among thofe Honourable Members, that it is impoflible fo to abridge them, (which are but Abridgments themfelves) as not to render them obfcure and unintelligible.
A
A
BARLE
Difcourfes contain’d in this Volume.
N Effimate of the Quantity of Vapours A raifed out of the Sea, as derived from — | Experiment: Together with an Account of the Circulation of the wat’ry Vapours of the Sea, and of the Caufe of Springs. Prefented to the Royal Society by Mr.E. Halley, F. R. S. Pag. 1- The True Theory ef the Tides, extraéted from that admired Treatife of Mr. Iaac Newton, Intituled ‘philofophiz Naturalis Principia Mathematica; being 4 Difcourfe prefented with that Bock to the
late King James, by Mr. E. Halley. 12 A Theory F the Variation of the Magnetical Com- pals, by Mr. E. Halley. 27
An Account & the Caufe of the Change of the Va- tiation of the Magnetical Needle. with an Hypothefis of the Strufture of the cue
a arts
The TABL et
Parts of the Earth ; as it was prefented to the Royal Society in one — their late Meetings, by Mr. E. Halley. Pp. 43 An Hiftorical Account of the ‘Trade-Winds and Monfoons, obfervable in the Seas between and near the Tropicks’; with an Attempt to affign the Phyfical Caufe of the faid Winds, by Mra E. Halley. 61 A .Difcourfe of the Rule of the. Decreafe. of the Heighth of the Mercury in the Barometer, according as Places ave elevated above the Stre face of the Earth 3 with an Attempt to difco- ver the true Reafon of the rifing and falling of the Mercury, upon Change of Weather, by Mr. E.. Halley. ot A Letter from Mr. Ifaac Newton, while Profef= for of the Mathematicks in the Univerfity of Gambridge ; containing his new Theory. about Light and Colours: Sent from Cambridge, Feb. 6. 1673. in order to be- communicated to the Royal Society. 97 A farther Explanation of the shee Theory.) 3.05 A Demonjlration concerning the Motion of Light, communicated from Paris. 118 An Introduttory. Effay to the Dotrine of Sounds, containing fome Propofals for the Improvement of ‘Agoutunle 5 as it was prefented to the Dub- lin Society, by the Right Reverend Father in God Narciflus, Lord Bifbop of Ferns and Leighlin. 121 A Difcourfe concerning the Modern ‘Theor y of ‘Generation, Jy Dr. Geo. Garden, of Aber= deen, being part 2 a Letter to Dr. William Mufgrave, L.L. BD. Reg. Soc. S. and by him c-mmunicated to the Ryal Saciefy, 24 4... 142 4
A foort Difcourfe concerning Conco€tion — Read at a Meeting of the Royal Society, by Clope- ton Havers, M. D: Fellow of the Royal So- etety. Page 155 A Difcourfe concerning fome Influence of Refpi- ration on the Motion of the Heart hitherto un- - obferved. By). Drake, M.D. F. R.S. 173 Some Thoughts and Experiments concerning Vege- ‘tation. By John Woodward, M. D. of the College of Phyficians and Royal Society, and Profeffor of Phyfick in Grefham-College. 205 | An Account of the Meafure of Gold upon Gilt. _ Wire 3 together with a Demonftration of the exceeding Minutenefs of the Atoms, or confti- tuent Parts of Gold; as it was read before the Royal Society, by Mr. E. Halley. = 245 An Account of Dr. Robert Hook’s Invention of the Marine Barometer, with it’s Defcription and Ufes. Publifbed by Order of. the Royal Soeiety by Mr. E. Halley. ot ‘A Difcourfe concerning the Proportional Heat of the Sun in all Latitudes; with the Method of collesting the fame, a it was read before the Royal Society in one of their late Meetings, by Mr. E. Halley. 258 Concerning the Diftance of the Fixed Stars, by the Honourable Fran. Roberts, Ef7; F. R. S. pes 27 Mr, Ifaac Newton’s Theory of the Moon. ad An Eftimate of the Degrees of the Mortality of ~ Mankind, drawn from Curious Tables of Births and Eunerals at the City of Breflaw; with an Attempt to afcertain the Price of Annuities _» upon Lives, by Mr. E. Halley: 282 | wes 4
i
f ua
; ‘
The TABLED
A Difcourfe concerning Gravity, and its Propere ties, wherein the Defcent of Heavy Bodies, and the Motion of Projects x briefly, but fully
handled : Together with the Solution of a Pro-
~ blem of great Ufe in Gunnery, by Mr. E. Hal-
ley. Pag. 304
A Propofition of General Ufe in the Art of Gunnery,
flewing the Rule of laying a Mortar to pafs, in order to ftrike any Objett above or below the Hor:- zon, by Mr. E. Halley. 326 'A Difcourfe concerning the Meafure of the Air’s Re- fiftance to Bodies moved init. By the Learned _ John Wallis, $.T. D. andFsR:Se . 33 ‘An Inflance of the Excellency of the Modern Alge- bra, in the Refolution of the Problem of finding the Foci of Optick Glaffes univerfally. By Mr. E. Halley, SRS. 350
APPENDIX.
An Analytical Refolution of certain Equations of
the 3d, §th, 7th, 9th Powers, and fo on ad Infinitum, in finite Terms, after the man- ‘ner of Cardan’s Rules for Cubicks. By Mr: A. Moivre, F. R. S. 265 A Difcourfe concerning the A&ion of the Sun and Moon on Animal Bodies 5 and the Influence which this may have in many Difeafes. By Richard Mead, 44D, F.R.S. 371
A
A Tranflation of Part of Mon- fieur Fontenelle’s Preface to the Memoirs of the Royal Acade- my at Paris, in the Year 1699.
treating of the Ufefulnefs of Mathematical Learning. — |
PD U T to what purpofe fhould People become
| fond of the Mathematicks and Natural Phi- lofophy. Of what ufe are the TranfaGtions of the Academy ? Thefe are common Queltion, which moft do not barely propofe'as Queftions ; and ir will not be improper to clear them.
People very readily call ufelefs, what they do not underftand. It is a fort of Revenge ; and as the Mathematicks and Natural Philofophy are known but by few, they are generally look’d up- onas ufelefs. ‘The reafon of this is ; becaufe they are crabbed and not eafily learat.
We have a Moon to light us in the Night ; What is it to us, fay they, whether Fupicer hath four ? Why fo many laborious Obfervations, fo many tedious Calculations to know exaétly their Courfe ? They’il not afiord us the more Light for it ; and Nature, which hath plac’d thefe little Planets without the reach of our Eyes, doth not - feem to have made them for.us. According to - this plaufible Argument they ought not to have . | been
—
Fontenelle, of the Ufefulnefs been obferv’d with a 'Telefcope, nor ftudy’d. But it is certain, that we had been confiderable Loo- —
fers by it: For thofe who have fome infight into
the Principles of Geography and Navigation know, that fince thefe four Moons about Fupiter have been difcover’d, they have been more ufeful to thofe Sciences than our own Moon ; and that they ferve, and fhall more and more ferve to: make ~ new Sea-Charts, infinitely more exad&t than the Old; and are likely to fave the Lives of a vaft many Seamen. Did we reap no other advantage
_from Aftronomy than this from thefe Satellites of
Fupiter, that wou'd be fufficient to juftifie thofe prodigious Calculations, thofe afliduous and nice Obfervations, this great number of elaborate In- ftruments, and this Noble Edifice built only for this Science. However the greateft part of Man- kind know nothing of thefe Satellites of Fupiter, unlefs perhaps by hear-fay, and that too confu- fedly ; or elfe they are ignorant of what Af- finity they have with Navigation, or of the great Improvements which have been lately made in it.
This is the Fate of Sciences, which are ftudy’d and improv'd by few. Moft People are not fene fible of their Progrefs, and efpecially when made in fome mean Callings. But what doth it figni- fie, that we can nowmoreeafily direét the Courfe of Rivers, cut out Ganals, and fettle new Navi gations ; becaufe our Method of taking the Level and making Sluces is infinitely better than heres tofore ? Some Mafons and Seamen have thereby found their Bufinefs eafier, but they themfelves were not fenfible of the Skill of the Geometrician who dire€ted them. ‘They were movd, as the Body by a Soul, it doth not know. Others are
yet
- of Mathematical Learning. yet lefs fenfible of the Genius that prefided over _ the Undertaking ; and the World is the better for its fuccerding well, but not altogether free from Ingraticude. _ Anatomy, which is fome time fince fo carefully ftudy’d, can’t become more exact, but Chyrurgi- cal Operations muft alfo be more fure. Surgeons _ know this; but thofe who receive the Benefit of their Art know nothing of it. And indeed how fhould they? They would be oblig’d to’ compare Old with Modern Surgery ; and this wou’d take too much Time, and go again{t the Grain: Sa that fince the Operation hath fucceeded well, they do not thiak it material to know whether it had fucceeded as weli in another Century. ~~ It is ftrange that fo many things are before our Eyes, and that we do not fee them. Your Han- dycraft Shops are full of ingenious Works ; but yet we hardly mind them: And very uféful and well contrivd Inftruments and Experi- ments want Spectators, who wou’d be won- derfully pleas, wou’d they take the pains to admire. them. ve - If aLearned Society have made fome Improve- ments in Geometry, Anatomy, Mechanicks, or any other ufeful Science, it muft not be expected, that the World will go back to fo remotea Sprin to thank and applaud them for the Ufefulnefs of their Produ€tions: For it will be more eafie to enjoy the Benefit of their Difcoveries and [m- provements than to know them. ‘The Determi- nation of Longitude by the Satellites, the Difco- very ofthe Duétus Thoracicus, amore convenient, and more exact Level, are not Novelties fo fit to make a noife asa pleafant Poem, or a handfome Piece-of Oratory. © )
a2 Altho?
Fontenelle, of the Ufefulnefs
~Altho’ the Ufefulnefs of Mathematicks and Na- tural Philofophy is obfcure, yet it is real. To confider Mankind in their Natural State, nothing is more ufeful to them, than what may preferve their Lives, and produce thofe Arts, which are both great Helps and Ornaments to Publick So- Cietics. : , ~ As for what concerns the Prefervation of Life, it peculiarly belongs to Phyfick ; which for that reafon is divided in the Academy into three Branches, which make three different forts of Members of this Society, Anatomy, Chymiftry, and Botanicks. Every Body knows of what Im- portance it is to have an exact Knowledge of Hu- man Body, and of what Medicines may be extra- &ted from Minerals and Plants. . | As for Arts, too tedious to be reckon’d, they depend fome upon Natural Philofophy , others upon Mathematicks. ae | One wou'd think at firft, that if the Mathema- ~ ticks were to be confin’d to what is ufeful inthem, they ought only to be improv’d in thofe things, which have an immediate and fenfible. afhnity
with Arts, and the reft ought to be negktted as
a Vain Theory. But thiswou’d be a very wrong Notion. As for Inftance, the Art of Navigation hath a neceflary Connexion with Aftronomy, and Aftronomy can never be too’much improv’d for the Benefit of Navigation. Aftronomy cannot be without Opticks by reafon of Perfpeétive Glaffes ; and both, as all other Parts of Mathe- maticks, are grounded upon Geometry, and to go as far as you can, even upon Algebra.
Geometry
of Mathematical Learning.
Geometry, and efpecially Algebra, are the Keys of all the Inquiries, that can be made con- cerning Magnitude. Thefe Sciences which are only converfant about abftrufe Relations, and fimple Ideas. may feem dry and barrén, whilft _ they keep within the Verge of the IntelleGtual World ; but mixt Mathematicks, which ftoop to Matter, and confider the Motion of the Stars; the Augmentation of moving Forces, the difle- rent Paflages of the Rays of Light through different Mediums ;the different Effe&ts of Sound by the Vibration of Things ; co conclude all thofe ‘Sciences, which difcover the particular Relations of Senfible Magnitudes go on farther and more fecurely, when the Art of difcovering Relations in General is more perfect. The Univerfal In- {trument cannot be too extenfive, too handy, or too eafily apply'd : It is ufeful to all the Sciences, and they cannot be without it: And therefore a- mong the Mathematicians of the Academy, who are defign’d to be ufefulto the Publick, the Geo- metricians and Algebrifts make a Clafs, as well as
the Aftronomers and Mechanicks. | ; rageesers it is certain, that Speculations pure- ly of Geometry, or of Algebra, are not about ufeful things: But it is certain too, that thofe that are not, either lead or belong to thofe that are. Itisinit felf a very barren thing to know, _ that in a Parabola a Subtengant is double the correfponding Ab‘ciffe ; but yet it is a Degree of Knowledge neceflary to the Art of throwing Bombs, fo exactly asthey can do now. ‘There are not by far fo many evident Ufes as Propofiti- ens or Truths in the Mathematicks: Yet it ts
enough if the Concourfe of feveral Truths is ge- nerally of fome-ufe. ; | a 3 Farther
Fontenelle, of the Ufefulnefs Farther , a Geometrical Speculation, which was not at firft applicable to any ufe, becomes fo — afterwards. When the greateft Geometricians in the Seventeenth Century fet about to ftudya - mew Curve, which they call’d a Gycloide, they only engag’d themfelves in a meer Speculation out of Vanity, ftriving to outdo one another by the Difcovery of difficule Theorems. They did not even pretend that this was for the Publick Good ; however by diving into the Nature of the Cycloide it was found, that it was deftin’d to make Pendulums as perfeGt as may be, and carry the Meafure of Time as far as it can go. oy It is the fame thing with Natural Philofophy as
with Geometry. The Anatomy of Animals feems infignificant ; and it only concerns us to know that of Human Body. But yet fome Parts of it, which are of fo nice, or fo confus’d a Make, that they are invifible, are fenfible and manifeft in the Body of an Animal. Hence it is, that Monfters themfelves are not to be neglected. ‘The Me- chanifm conceal’d in a particular Kind or in a common Make, is unfolded in another kind, or in an extraordinary Make ; and one wou’d be e. apt to fay,that Nature by multiplying and varying fo much her Works, can’t jometimes forbear be- traying her Secrets. All that the Antients knew of the Load-ftone, was, that it attraéts Iron. But whether they did not value a Curiofity, which promis‘d them nothing ; or that their Genius did — not lead them to make Experiments, they have not examin’d this Stene as carefully asthey might. One Experiment taught them, that it turns of its felf towards the Poles of,the World, and did put into their Hands the ineftimable Treafure of the Mariners Compafs. They might eafily ose | : | ‘made
of Mathematical Learning. made this Difcovery important, and yet they did not doit; and if they had fpent a little more time upon aCuriofity which feem’d ufelefs to them, the Latent ufe of ichad foon appear’d. Let us always make a Collection of Mathema- tical and Phyfical Truths; happen what it will we can’t hazard much by it. It is certain, that they fhall be drawn from Springs, whence agreat many ufeful ones have already at drawn. We have reafon to prefume, that we fhall draw from thence, fome that fhall fhine as foon as they are difcoverd, and convince us of their Ufefulnefs. Other Truths fhall ftay fomé time tiil a piercing Meditation, or fome happy Accident difcovers their Ufe. Some Truths being confider’d by them- felves fhall be barren, till they are confider’d with reference to one another.Laftly,let the worfe come to the worfe, fome fhall be eternally ufelefs, I mean ufelefs with reference to fenfible and egrofs Ufes ; for otherwife they fhall not be fo. An Objeé& upon which alone you caft your Eyes is the clearer and brighter, when the neighbouring - Objects, which however you do not look upon, are alfo enlighten’d ; becaufe it hath the Benefit of the Rays, which are reflected from them. Thus thofe Difcoveries,which are palpably ufeful,and de- ferve our chiefeft Attention, are in fome meafure enlighten’d by thofe, which may be call’d ufelefs. For all Truths make one another more lucid. It is always ufeful to have right Notions, even of ufelefs Subjefts, And tho” we cou’d reap na benefit by the Knowledge of Numbers and Sines, yet ic woud ftill be the only certain Knowledge berated to our Natural Light, and they wou’d erveto give ourReafon the firft Habit of and Incli- + Bane" | Bhacd nation
Fontenelle, of the Ufefulnefs Nation to Truth. They wou’d teach us too - Perate upon Truths; to take the. Thread of . them, which is generally very fine and al- moft imperpeceptible ; and to follow it as far as it reaches: In a word, they woud make Truth fo familiar, that we might on other Occafions know it at firft fight, and almoft by . Initinct. : _ A Geometrical Genius is not fo confind to Geometry, but that it may be capable of lear- ning other Sciences. A Traét of Morality, Po- Jiticks, or Criticifm, and even a Piece of Ora- tory, fuppofing the Author qualify’d otherwife for thofe Performances, fhall be the better for being compos’d by a Geometriciane That Or- der, Perfpicuity, Precifion and Exactne(s, which fome time fince are found in good Books, may originally proceed from that Geometrical Genius, which is now more common than ever, and in fome manner is communicated. by one Relation to another, nay even to thofe that do not underftand Geometry. Sometimes a Great Man draws all his Cotemporaries after him ; and he who hath the jufteft Claim to to the Glory of having fertled a new Art of Arguing, was an Excellent Geome- trician.
Laftly, whatever raifes us to Great and Noble . Reflexions, tho’ they be purely Speculative, af- ford a Spiritual and Philofophical Usility. The. Wants of the Mind are perhaps as many as thofe of the Body. She defires to extend her Know- > ledge: All that can be known, is neceflary to >) her, and there can be no better Proof than this, + that fhe is defign’d for Truth. Nothing perhaps +> can'redound more to her Glory, than the Pleas): fure that is felt fometimes, in fpight of ones
feif,
of Mathematical Learning. felf, in the dry and crabbed Queftions of Alge- At 3 :
But without running counter to the common Notions, and recurring to Advantages which may feem too far fetch’d and refin’d, it may fairly be ownd, that the Mathematicks and Natural Philo- fophy have fome things which are only fubfervi- ent to Curiofity ; and fo have thole Sciences — which are moft generally acknowledg’d to be ufe- ful, as Hiftory, &c.
Hiftory doth not in every Part of it fupply us with Examples of Vertue and Rules for our Be- | haviour. For befides thefe, therein you have a View of the perpetual Revolutions of Human Af- fairs, of the Beginning and Fall of Empires, of Manners, Cuftoms, and Opinions which conti- nually fucceed one another; and in a word, of all that rapid, tho’ infenfible, Motion that carries all before it, and inceffantly alters the Face of the Earth. |
Had wea mind to oppofe Curiofity to Curiofity, we fhou’d find that inftead of the Motion, which agitates Nations, and gives birth to, and deftroys States ; Natural Philofophy confiders that Great and Univerfal Motion, which hath put the whole Frame of Nature in Order, and fufpended che Coeleftial Bodies in feveral Spheres, and which | illuminates and extinguifhes fome Stars ; and by following always unalterable Laws, diverfifes its effects “ad infinitum. TE. the furprifing difference of Manners and Opinions: of >Mankind is {0 en- tertaining; there is too a great deal of Pleafure | to ftudy the prodigious diverfity of the Stru@ure of the different Species of Animals, with refe- rence to their different Fun@tions, to the Ele- ments they live in, to the Climates they inhabit, : and
Fontenelle, of the Ufefulnefs and the Aliments they are to take, €Jc. The moft curious ftrokes of Hiftory fhall hardly’ be more- curious than the Phofphorus, the cold Liquors which being mixt together, break out into a flame ; Silver ‘Trees, the al- moft Magical Operations of the Load-Stone, and a vaft number of Secrets, which Art hath difcover’d by a near and diligent Scrutiny of Nature. | a
Laftly, Natural Philofophy doth as much as it is poflible unravel the Footfteps of that ~ Infinite Intelleét and Wifdom, whe hath made all things: Whereas the Object of Hiftory are the diforderly Effects of the Paffion, and of Humane Caprices; and fo odd a Series of T’vents, that tiie formerly faney’d that a Bing and Senfelefs Deity had the Dire€tion of - them.
We mutt not look upon the Sublime Reflexi- ons which Natural Philofophy Jeads us to make - concerning the Author of the Univerfe, as meer Curiofities. For this ftupendous Work, which appears always more wonderful the more we _ know it, gives us fuch exalted Notions of its Maker, that they fill our Minds with Admirati- on and Refpeé&t. But above all, Aftronomy and Anatomy are the two Sciences which more pal- pably lay before us two grand Attributes of our Creator; one his Immenfity by the diftance, Mag- nitude and Number of Coeleftial Bodies ; the o- ther his Infinite Knowledge by the Mechanifm of Animals. ‘True Natural Philofophy is a kind. of Theology. Ny aghog
eo
of Mathematical Learning. The different views of Humane Underftand- ing are almoft infinite; and Nature is really fo. So that we may every day expect fome Difco- veries, either in Mathematicks or Natural Phi- lofophy, which fhall be of a new fort of Utility or Curiofity. Make a Colletion of all the diffe- rent Advantages which the Mathematicks afford- ed a Hundred Years ago, and you'll find no- thing to be compar’d to the Perfpective Glaffes they have furnifh’d fince that time, and which. are a new Organ to the Sight, and cou’d not be expected from Art. How furpriz’d had the Ans ' cients been, if they had been told that their Po- fterity, by the help of fome Inftruments, fhoud one day fee a vaft number of Objects which they did not fee; a Heaven that was unknown to them ; and Plants and Animals they did not even fufpect it was poffible to exift. Naturalifts had al- ready a great many curicusExperiments; but with- in about half a Century, the Air-Pump hath pro- duced a prodigious quantity ofthem wholly new, and which by fhewing Bodies in a Space void of Air, fhews them as tranfported in a World dif- ferent from ours, where they undergo Alterations whereof we had no Notion. The Excellency of Geometrical Methods, which are every day in- vented and improv’d, may perhaps at laft ex- hauft Geometry ; that is, The Art of ma- _ king Geometrical Difcoveries, and that is all: _ Whereas Natural Philofophy, which contemplates an Object of an unlimited Variety, and Fecundity, fhall always find room for new Obfervations, and opportunities to increafe its vaft Stock, and fhall have the Advantage of never being a compleat
‘Science. - There
Fontenelle, of the Ufefulnefs
There are fo many things to be difcover’d, : whereof a great part, in all likelyhood fhall ne- ver be known ; that they give an opportunity to thofe who will not encounter with the Thorns and Difficulties of Natural Philofophy, to affe& a fort of Difcouragement. A great many to vilify this Natural Science, pretend a mighty venerati- on for the works of Nature, and that they are abfolutely incomprehenfiblee However, Nature is never fo admirable, nor fo admir’d as when known. ‘True it is, that what is known is in- confiderable in comparifon of what is not yet known. Nay, Sometimes what is not known, is exactly what feems fhou’d be the fooneft known. As for inftance, it is not at leaft cer- tainly known, why a Stone thrown up into the Air falls down again ; but we certainly know the. caufe of the Rainbow, why it doth not exceed a certain height ; why its breadth is always the fame; why when there are two Rainbews at the: fame time, the Colours of the one are overfet with reference to the Colours of the other; and. yet the fail of a Stone in the Air appears a more fimple Phzenomenon, than the Rainbow. But in a word, altho’ we do not know every thing, we. are not neither ignorant of every thing. And altho’ we are ignorant of the moft fimple Events, yet we have a knowledge of what feems the moft Complex. So that if we have on the one hand __ reafon to fear, left our Vanity fhoud flatter uz with the hopes of attaining to the knowledge of. things above our reach; on the other we ought, © to dread, left our Slothfulnefs fhould alfo flat- ter us that we are condemn’d to a greater degree’ of Ignorance than really we are. ‘og
People |
Rc! y be
of Mathematical Learning. _ People may think that the Sciences do not be- gin to exert themfelves, either becaufe they cou’d be but imperfe€&t among the Ancients; or becaufe we have almoft loft the Footfteps of them du- ring the gloomy Darknefs of Barbarity; or be. caufe a better method hath been taken about 100 Years ago, Was the Progrefs Hiftorically examin d, they have already made in {0 fhort a time, notwithftanding the ftrong, but falfe Pre- judices they had long to encounter with, even - fometimes the foreign Obftacles they have met with from Authority and Power ; the want of Zeal for Sciences fo remote from common ule, thofe few who apply’d themfelves to this Work, and the weak Motives which engag’d them in it; a Man would wonder at the Greatnefg and Rapidity of the Progrefs of the Sciences, and even we might obferve fome new ones to ftart out of nothing, and perhaps be. tempted to have too great hopes of future Impcove- ments. | The greater reafon we have of future Succefs, the greater we have to look upon the Sciences as in their Cradles, at leaft Natural Philofophy. ‘And therefore the Academy is only now employ’d to make an ample Provifion of Obfervations, and Faéts well attefted, which may one day be the foundation of a Syftem. For before the Syftematical Natural Philofophy can raife {o- lid Edifices ; Experimental Natural Philofophy muft be in a condition to fupply it with good Materials. |
- None
Fontenelle, of the Ujefulnefs —
None but Societies, of thofe too countenanc’d ~ and encourag’d by the Prince, can fuccefsfully make and prepare this Colle€tion of Materials. All the Learning, Care, Life and Wealth of one Private Man can never anfwer this Defign. There are too many different Experiments to be made, which are to be too much varyd, and a long time frofecuted with the fame ‘Temper and Mind. ‘The Caufeof the leaft Effect is fo wrapd up, that unlefs you very carefully open all the various Foldings, you cannot come © at it.
Hitherto the Academy of Sciences hath con- fider’d Nature but by parcels: They have fix’d upon no general Syftem, for fear of falling into the inconveniency of hafty Syftems, which are very grateful to the impatience of Humane Un-- derftanding ; and being once fettled, are Obfta- cles to what Truths are afterwards difcover’d. This day we are fure of a Fat, to morrow we fhall be fure of another that hath no relation with the former. However fome Conjectures are venturd at upon Caufes; but they are only ConjeGtures. So that this ColleGion, which - the Academy gives to the Publick, is compos’d of feparate Fragments, independant of one anos ther; whereof every one who is the Author, warrants the Facts and Experiments ; and whofe Arguments are approv’d by the Academy, but with Reftri€tions becoming Wife and Wary Scepticks. ie | |
‘Time perhaps will come, when thefe fcat- ter’d Fragments fhall be united into one regu- Jar Body; and if they be fuch as they are wifh’d, they may of themfelves Unite. A great many Truths, when their Numbers is confide-
rable,
of Mathematical Learning. rable, fhew fo near a Relation to, and fo mu- tial a Dependance upon one another, that ie feems, that notwithftanding their violent Se- | paration, they have a natural Tendency to be _ re-united.
Mifcellanea
ee eee ie
MiscELLANEA Curiosa.
An Eftimate of the Quantity of the
_ Vapours raifed out of the Sea de- rived from Experiment: Toge- ther with an Account of the Cir- culation of the-watry Vapours of the Sea, and of the Caufe of Springs, -prefented to the Royal Society. a
By Mr. E. Halley, F. B.S.
HAT the Quantity of Aqueous Vas _ pouts contain’d in the Medium of the Air, is very confiderable, feenis moft
evident from the great Rains and
Snows which are fometimes obferv’d to fall, to that degree, that the Water thus dif- charg’d out of the Interftices of the Particles of Air, is in weight a very fenfible part of the in+ cumbent Atmofphere: But in what proportion thefe Vapours rife, which ave the Sources not only of Rains, but alfo of Springs or Fountains {as I defign to prove) has not, that 1 know of, Deen any where well examin’d, tho’ it feem ta
be one of the moft neceflary Ingredients of a js . : B Rea!
2 Mifcellanea Curiofa. Real and Philofophical Meteorolegy, and, as fuch; to deferve the Confideration of this Honourable Society. I thought ic might not be unacceptable to attempt by Experiment to determine the Quan- tity, of the Evaporations of Water, as far as they arife from Heat, which upon ‘Trial fuecceeded as - follows. We took a Pan of Water, adout 4 Inches deep, and 7 Inches 7% D’ameter, in which we — placed a Thermometer, and by means of a Pan of Coals, we brought the Water to the fame de- grce of Heat, which is obferved to be that ofthe Air in our hotteft Summer; the. Thermometer nicely fhewing it: This done, we afhxed the Pan of Water, with the Thermometer in it, to one end of the Beam of a Pair of Scales, and. ex- aétly counterpois’d it with weights in the other Scale ; and by the application or removal of the Pan of Coals, we found it very eafie to. main- tain the Water in the fame degree of Heat pre- cifely. Doing thus we found the weight of, the Water fenfibly to decreafe ; and at the end of two hours we obferved that there wanted half an Ounce Troy, all but 7 grains, or 223 grains of Water, which in that time had gone off in Va- — pour ; tho’ one could hardly perceive it fmoke, and the Water were not fenfibly warm. ‘This Quantity in fo fhort a time feend very confide- rable, being little tefschan 6 ounces in 24, hours, from fo {mall a Surface as a Circle of 8 Inches Diameter. ‘To reduce this Experiment to an ex- a&t Calculus, and determine the thicknefs of the ‘Skin of Water thathad {0 evaporated, I aflume the Experimentalledg'd by Dr. Edward Bernard to. have been made in the Oxford Society, viz. That the Cube-foot Englifp of Water weighs exaétly 76 a Pounds
PERE TOPE CL UMERAL TAN Je oh a AT Nee fk Bn j
Mifcellanea Curiofé. gh Pounds Troy ; this divided by 1728, the number of Inches ina Foot, will give 253} grains, or 2 ounce 133 grains for the weight of a Cube-inch of Water ; wherefore the weight of 233 grains is 237 or 35 Parts of 38 ofa Cube-inch cf Was ter. Now the Area of the Circle whofe Diameter 18 7%5 Inches, is 49 {quare Inches: by which dit viding the Quantity of Water evaporated, Vizs $3 Of an Inch, the Quote $3.5 or ts fhews that the thicknefs of the Water evaporated was the _§3d part of an Inch ; but we will fuppofe it only the 6oth part, for the Facility of Calculation. If therefore Water as warm as the Air in Summer, -exhales the thicknefs of a 6cth part of an Inch in » two hours from its whole Surface, in ra hours it will exhale the x5 of an Inch; which Quantity will be found abundantly fufficient to férve for. all the Rains, Springs, and Dews ; and account for the Ca/pian Sea, being always at a ftand, heitaer wafting nor overflowing ; as likewile for the Current faid to fet always in at the Streights of Gibraleer, tho’ thofe Meditterranean Seas re= ceive fo many and fo confiderable Rivers. To eftimate the Quantity of Water arifing in Vapours out of the Sea, I think I ought to cons | fider it only for the time the Sun is up, for that the Dews return in the Night, as much if not more Vapours than are then emitted ; and in Summer the Days being no longer than 12 hours, this Excefs is ballanc'd by the weaker A€tion of the Sun, efpecially when rifing before the Water be warmed : So that if I allow 4, af amInchof the Surface of the Sea, to be raifed per diem in Va- pours; it may not be animprobable Conjecture,
B 4 Ups
4 ——— Mifcellanea Curiofa. :
Upon this Suppofition, every 10 fquare Inches.
of the Surface of the Water, yields in Vapour
per diem a Cube-inch of Water ; and each fquare ©
Foot half a Wine-pint ; every Space of 4 Foot fquare, a Gallon ;.a Milefquare, 6914. Tons; a
fquare Degree fuppofe of 69 Englifh Miles, will |
evaporate 22 Millions of Tons: And if the Me- -diterranean be eftimated at forty degrees long and
four broad, allowances being made for the Places where itis broader, by thofe where it is narrower
(and I am fure I guefs at the leaft) there will be
1€0 Square degrees of Sea; and confequently, —
the whoie Mediterranean muft lofe in Vapour,
in a Summer’s day, at leaft 5280 Millons of
Tons, And this Quantity of Vapour, tho’ very’
great, is as little as can be concluded from the lixperiment prodticed: And yet there-remains
_.another Caufe, which cannot be reduced to Rule, “I mean the Winds, whereby the Surface ‘of the Water is licked up fome times fafter than it ‘ex-
hales by the heat of the Sun; as is well known to thofe that have confiderd thofe drying Winds which blow fometimes. Panes Se To eftimate the Quantity. of Water, the’ Medi- terranean Sea receives from the Rivers that. fall isto it, is.a very hard Task, unlefs one had ‘the
Opportunity to meafure their Chanels and Veloci-
ty; and therefore we can only do it'by allowing more than enough; that is, by affuming thefe' Rivers greater than in ail probabilicy they bey
and then comparing rhe Quantity of Water void=
ded by the “Thames, with that of thofe Rivers,’ whofe Waters we delire to compute. Rates The Mediterranean ‘receives thefe confidera-’
ble Rivers; the Iberus, the Rhone, the Trber,~ the Po, the Danube, the Neifter, the Boryftenesy | the
BP De ee a Gee Ne dt ry “Se Beale f ri) Kor
— —— Mifcellanea Curiofa. 5 _ the Tanais, and the Nile ; al! the reft being of no _ great Note, and their Quantity of Water incon- fiderable: Thefe nine Rivers, we wil! fuppofe each of them to bring down ten times as much Water asthe River Thames ; not that any of them is great in reality, but to comprehend with them all the {mall Rivulets that fall into the Sea, which otherwife I know not how to allow Eitore: 3 | erie! . To calculate the Water of the Thames, I af- fume that at Kington Bridge where the Flood ne- ver reaches, and the Water always runs down, the breadth of the Chanel is 100 Yards, and its Depth 3, it being reduced to an Equality (in both which Suppofitions I am fure I take with the moft) hence the Profil of the Water in this Place is 200 fquare Yards: This multitplied by 48 Miles (which I allow the Water to run in 24 hours, at 2 Miles an hour) or. 84480 Yards, gives 25344000 Cubick-yards of Water to be evacuated every Day; that is, 20300000 Tons per diem; and I doubt not, but in the excefs of of my Meafures of the Chanel of the River, I have made more than fufficient allowance for the Waters of the Brent, the Wandel, the Lea, and Darwent, which are all worth notice, that fall in- to the Thames below Kingfton.. : _. Now if each of the aforefaid 9 Rivers yield 10 _ times as much Water as the Thames doth, "twill follow that each of them yields but 202 Milli- ons of ‘Ton per diem, andthe whole 9, but 1827 Millions of Tons in a day ; which is but little more than } of what is proved to be raifed in vapour out of the Mediterranean in 12 hours time. Now what becomes of this Vapour when rais’d, and how it comes to pafs és . B 3 that
* ? . a ah i Tre sande
6 Mifcellanea Curiofa. | that the Current always fets in at the Mouth, of the Streights of Gibralter, fhall immediately be fhew’d : Bur firft it is neceflary to advertife the Reader, that in making the Experiment herein mention’d, the Water ufed had been’ falted to the fame degree as is the common Sea-water, by the Solution of abouta 4oth partof Sale
HA thus fhew’d by Expetiment the Quan-° : tity of Water raifed in Vapour from the Surface of the Sea in a Days time, which was fo far approv'd of by fome Honourable Members of this Society, that I receiv’d their Commands to profecute thefe Enquiries; and particularly, in relation to the Method ufed by Nature, to re- curn the faid Vapours again into the Sea; which is fo juftly perform’d, that in many hundred of Years we are fufficiently aflured that the Sea has not fenfibly decreafed by the lofs in Vapour; _ nor yet abounded by the immenfe Quantity of frefh it receives continually from the Rivers. — To'demonftrate this Equilibre of Receipt and Expence in the whole Sea, is a Task too hard for me to undertake, yet in obedience to thofé whom I have the Honour to ferve, I fhall here offer, what to me has hitherto feenyd the moft fatisfactory Account of this grand Phenomenon : J have in another place attempted to explain the manner of the rifing of Vapour by Warmth, by fhewing, that if an Atom of Water ‘were expanded into a Shell or Bubble, fo as to be ten times as big in Diameter as when it was Wa- ter; fuch an Atom would become fpecitically lighter than Air, and rife fo long as that Flatus or warm Spirit that firft feparated it from the Mafs of Water, fhall continue to diftend it to the fame yal ey ey ward * ne Re hy 2 eae eae: Degree 5
Mifcellanea Curiofa, 7 Degree; and that Warmth declining, and the
_ Air growing cooler and alfo fpecifically ligh-
ter, the Vapours confequently fhall {top at a
certain Region of the Air, or elfe defcend, which
wie re
may happen upon feveral accounts, as I fhall by and by endeavour to make out; yet I undertake not that this is the only principal of rhe rife of Vapours, and that there may not be a certain fort
of Matter, whofe Conatus may be contrary tothat
of Gravity ; as is evident in Vegitation, where in the Tendency of the Sprouts is dire&tly up- wards, or again{t the Perpendicular. But what ever is the true Caufe, it is in Fact certain, that warmth does feparate the Particles of Water, and emit them with a greater and greater Velocity, as the heat is more and more intenfe ; as is evi- dent in the Steam of a boiling Cauldron, where- in likewife the Velocity of the afcent of the Va-
- pours does vifibly decreafe till they difappear, be.
ing difperfed into and ailimulated with the Am- bient Air. Vapours being thus raifed by warmth, Jet us for a firft Suppofition put, that the whole Surface of the Globe were all Water very deep, or tather that the whole Body of the Earth were Water, and that the Sun had its diurnal courfe about it: I take it, thatit would follow, that the Air of it felf would imbibe a cercain Quantity of
aqueous Vapours, and retain them like Salts dif. folved in Water; thar the Sun warming the Air, and raifing a more plentiful Vapour from the Water in the day-time, the Air would fuftain a greater proportion of Vapour, as warm Water
_ willhold more diffolved Salts, which upon the ab-
fence of the Sun in the Nights would be all again difcharged in Dews, analogous to the Precipita- tion of Salts on the cooling of the Liquors ; nor
B 4 ae
+
8 — Mifcellanea Curiofa. is it to be believed that in fuch Cafe there would be any diverfity of Weather, other than periodi- — cally, every Year alike; the mixture of all ter- -reftrious, faline, heterogenious Vapours being — taken away, which as they are varioufly com- — pounded and brought by the Winds, feem to be the Caufes of thofe various Seafons which we now find. Inthis cafe the Aiery Regions every where, at the fame height, would be equally replenifh- — ed withthe Proportion of Water it could contain, regard being only tq be had to the different de- gree of warmth, from the nearnefs or diftance of the Sun ; and an eternal Eaft-wind would blow all round the Globe, inclining only tothe fame fide —
of the Ea/?, as the Latitude doth from the Equator 5 as is obferved in the Ocean between the ‘Tropicks. Next let us fuppofe this Ocean interfperfed with wide and fpacious ‘Tracts of Land, with high Ridges of Mountains, fuch as the Pyrenean, — the Alps, the Apennine, the Carpathian in Europes Taurus, Caucafus, Imaus, and feveral others in Afia; Atlas. and the Montes Luna, with other unknown Ridges in Africa, whence came the Nile, the Nigre, and the Zaire: And in Ame- rica, the Andes and the Apalatean Mountains ; each of which far furpafs the ufual height to ~ which the Aqueous Vapours of themfelves afcend, and on the tops of. which the Air is fo cold and rarified, as to retain but a fmall part of thofe Vapours, that fha!l be brought thither by Winds, Thefe Vapoursthercfore that are raifed copioufly in the Sea, and by the Wind, are carried over the low Land to thofe Ridges of Mountains, are there compelled by the Stream of the Air ro mount up with it to the tops of the Moun- | tains, where the Water prefently precipitates, gleeting
MifcellaneaCuriofa. 9
gleeting down by the Crannies of the Stone ; and part of the Vapour entering into the Ca- verns of the Hills, the Water thereof gathers as in an Alembick into the Bafons of Stone it finds ; which being once fill’d, all the overplus of Wa- — ter that comes thither runs over by the loweft place, and breaking out by the fides of the Hills, forms fingle Springs, Many of thefe running down by the Valleys or Guts between the Ridges ofthe Hills, and coming to unite, form little Ri- -vulets, or Brooks: Many of thefe again, meet- ing inone common Valley and gaining the plain
_ Ground, being grown lefs rapid, become a River 5 and many of thefe being united in one common Channel, make fuch Streams as the Rhine, the Rhone, the Danube ; which latter, one would hard- ly think the Colle&tion of Water condenfed out of Vapour, unlefs we confider how vaft a Tra& of Ground that River drains, and-that it istheSum | of all thofe Springs which break out on the South fide of the Carpathian Mountains, and on the North fide of the immenfe Ridge of the Alps, which is one continued Chain of Mountains from Switzerland, tothe Black-Sea And it may almoft
_ pafs for a Rule, that the magnitude of a River, * or the quantity of Water it evacuates, is propore - tionable to the length and height of the Ridges from whence its Fountains arife. Nowthis The- ory of Springs is not a bare Hypothefis, but found- ed on Experience, which it was my luck to gain in my abode at St. Helena, where in the Night- time, on the tops of the Hills, about 800 Yards above the Sea, there was fo {trange a conden- ~ fation, or rather precipitation of the Vapours, that it was a great Impediment to my Cceleftial Obfervations ; for in the clear Sky, the Dew bs | would
10 Mifcellanea Cuviofa would fall fo faft, as to cover,each half quarter of an Hour, my Glaffes with little drops; fo that I was neceflitated to wipe them fo often, and my Paper on which I wrote my Obfervations would immediately be fo wet with Dew, that it would not bear Ink: By which it may be fuppos’d how faft the Water gathers in thofe mighty high Ridges I but now nam’d. cow, Thus is one part of the Vapours blown upon the Land return’d by the Rivers into the Sea, from. whence they came; another part by the cool of the Night falls in Dews, or elfe in Rains, again into the Sea before it reaches the Land, which is by much the greateft part of the whole Vapours, becaufe of the great extent of the O- cean, which the motion of the Wind does not traverfe in a very long {pace of Time; and this is the Reafon why the Rivers do not return fo much into the Mediterranean, as is extracted in- ro Vapour. A third part falls on the Low. Lands, and is the Pabulum of Plants, where yet it does not reft, but is again exhaled in Vapour by the action of the Sun, and is either carried by the Winds to the Sea to fall in Rain or Dew there, or elfe to the Mountains to be there turn’d into Springs; and tho’ this does not im- mediately come to pafs, yet after feveral Vicife fitudes of rifing in Vapour, and falling in Rain or Dews, each Particle of the Water is at length return’d to the Sea from whence it came. Add to this, that the Rain=waters after the Earth is fully fated with moifture, does, by the Vallies ot lower parts of the Earth, find its way into the Rivers, and fo is compendioufly fent back | to the Sea, After this manner is the Circula- tion perform’d, and I doubt not but this Aypo- ae | a ee, thefis
Mifcellanea Curcofa. 41
thefis is more reafonable than that of thofe who
derive all Springs from the Rain-waters, which
yet are perpetual and without diminution, even
when no Rain falls for a long {pace of time 5 or
that derive them from a-Filtration or Percola-
tion of the Sea-waters, thro’ certain imaginary Tubes or Paflages within the Earth wherein they lofe their Saltnefs. This, befides many others, labouring under this principal Abfur- dity, that the: preateft Rivers have their moft copious Fountains fartheft from the Sea,. and whether fo great quantities of frelh Water can- not reafonably be deriv’d any other way than in Vapour. ‘This, if we may allow final Caufes, feems to be the defign of the Hills, that their Ridges being plac’d thro’ the midft of the Cons tinents, might ferve, as it were, for Alem- bicks to diftil frefh Water for the ufe of Man and Beaft, and their heights to give a defcent
to thofe Streams to run gently, like fo many
Veins, of the Macrocofm to be the more benefie
cial to the Creation. “If the difference be- _ tween Rain and Dew, and the caufe why fome-
times “tis Cloudy, at other times Serene, be inquir’d, I can offer nothing like a proper So-
_ lution thereof, only with fubmiffion to _propofe
Conjectures, which are the beft I can find, viz. ‘That the Air being heaped up by the meeting
_ of two contrary Winds, when the Mercury 1s
high, the Vapours are the better fuftain’d and kept from Co-agulating or Condenfing into
_ Drops, whereby Clouds are not fo eafily gene- _ ated, and the Night the Vapours fall down fingle, as they rofe in imperceptible Atoms
and the Air rarified by the Exhauftion there-
of Water : Whereas, when the Mercury is low,
of,
pacer i cae Mates BL) picts Gea ye aR ee Bye) a i Meme E on
12 Mifcellanea Curiofa. of, by two contrary Winds blowing from the place; the Atoms of Air keep the Vapours not~ fo well feparated, and they coalefce into vifible Drops in the Clouds, and from thence are: eafily drawn into greater Drops of Rain ; to which ’tis poffible and not improbable, that fome fort of Sa- line or Angular Particles of Terreftrial Vapour | being immix’d with the Aqueous, which I take to be Bubbles, may cut: or break their Skins or Coats, and fo contribute to their more fpeedy — Condenfation into Rain. |
The
— Mifcellanea Curiofa.
The Tie Theory af the Tides, ex- tratbed from that admired Trea- ’ tife of Mr. Mfaac Newton, Inti-
tled, Philofophie Naturalis | Principia Mathematica ; Being
a Difcourfe prefented with that
Book to the late King James, by
Mr. Edmund Halley.
WT ma), perbaps, feem ftrangey that this Papery being no other than a particular Account of a Book long fince publifhed, fhould now appear here; but the Defires of feveral honourable Perfons, which could not be withftood, have obliged us to infert it here, forthe Sake of fuch, who being le{s knowing in Mathematical Matters, and therefore not daring to adventure on the Author himfelf, are notwith{tanding, very curious to be inform’d of the Caufes of Things; particularly of fo general and extraordinary Phenomena, as ave thofe of the Tides. Now this Paper having been drawn up for the late King James's Ufe, (in whofe Reign the Book was publifh 4) and having given good Satisfattion to thofe that got Copies of it 5 it is. hop- ed the Savans of the higher. Form will indulge us this Liberty we take to gratifie their Inferiours in point of Science; and not be offended, that we here " infift more largely upon Mr. Newton’s Theory of the Tides, which, how plain’ and eafie focver we find, is very little pig by the common: Reas
aer. E H E
Ag Rie Baio ek
14 Mifcellanea Curiofa. =
FOHE fole Principle upon which this Autho? © T proceeds to explain moft of the great and © furprizing Appearances of Nature, is no other than that of Gravity, whereby in the Earth all Bodies have a tendency towards its Centre; as is moft evident: And from undoubted Arguments it’s. proved, that there is fuch a Gravitation to- wards the Centre of the Sun, Moon, ard all the Planets. : | bi toee
From: this Principle, as a. neceffary Confe- quence, follows the Sphrerical Figure of the Earth and Sea, and of all the other Coeleftial Bo- dies: And tho’ the tenacity and firmnefs of the Solid Parts, ftipport the Inequalities of the Land above the Level; yet the Fluids, preiling equal- ly and eafily yielding to each other, foon reftore _ the 4quilibrium, if difturbed, and maintain the
exact Figure of the Globe. Meret
Now this force of Defcent of Bodies towards the Centre, is not in all places alike, but is’ ftill lefs and lefs, as the diftance from the Center en- creafes: And in this Book it is demonftrated, that this Force decreafes as the Square of the diftance increafes ; that is, the weight of Bos dies, and the Force of their Fall is. lefs, in parts more removed from the Center, in the propor tion of the Squares of the Diftance. So as for Example, a T'on weight on the Surface of the -Harth, if it were raifed to, the height of 4000 Miles, which I fuppofe the Semidiameter of the Earth, would weigh but 3 of a Ton, or ¢ Huns dred weight: If to 12000 Miles, or 3 Semidi- © ameters from the Surface, that is 4 from the — Genter, it would weigh but yy part of the Weight on the Surface, or a Hundred and Quarter: So that it would be as eafie for the
Strength
; Mifcellanea Curiofa. 15 Strength of a Man at that height to carry a Ton weight, as here on the Surface a 100g. And in the fame Proportion does the Velocities of the fall of Bodies decreafe: For whereas on the Surface of the Earth all things fall 16 Foot in a fecond ; at one Semidiameter above, this fall’ is but four Foot; and at three Semidiame- ters, or four from the Centre, ic is but gg of the Fall at the Surface, or but one Foot in a ‘fecond: And ar greater Diftances both Weight and Fall become very fmall, but yet at all given Diftances is ftill fome thiag, tho’ the Effect be- come infenfibie. At the diftance of the Moon (which I will fuppofe 60 Semidiameters of the Earth) 2600 Pounds weigh but one Pound, and the fall of Bodies is but +455 of a Foot in a fe- cond, or 16 Foot in a Minute ; that is, a Body. fo far off defcends in 2 Minute no more than _ the fame at the Surface of the Earth would do in a Second of Time. i ___ As was {aid before, the fame force decreafing after the fame manner is evidently found in the Sun, Moon, and all the Planets; but more e fpecially in the Sun, whofe Force is prodigious 5 _ becoming fenfible even in the immenfe diltance of Saturn: This gives room to fufpect, ‘that the force of Gravity is in the Coeleftial Globes pro- portional to the quantity of Matter in each of them: And the Sun being at leaft ten Thoufand times as big as, the Earth, its Gravitation or at- _ tracting Force, is found to be at leat ten Thou- fand times as much as that of the Earth, ating on. Bodies at the fame diftance. _ This Law of the decreafe of Gravity being ' demonftratively proved, and put paft contra- diétion ; the Author with great Sagacity, in- quires into the. neceflary Confequences phistis up-
16 Mifcellanea Curiofa.
Suppofition ; whereby he finds the gehuine
Gaufe of the feveral Appearances in the Theo-
ry of the Moon and Planets, and difcovers the —
hitherto unknown Laws of the Motion of Co-
mets, and of the Ebbing and flowing of the Sea. — Each of which are Subje&ts that have hitherto — taken up much larger Volumes ; but Truth — being uniform, and always the fame, it is admi-
rable to obferve how eafily we are enabled to make out very abftrufe and difficult Matters, when
once true and genuine Principles are obtain’d : ; And on the other hand it may be wondred,
that, notwithftanding the great facility of truth,
and the perplexity and nonconfequences that ale
ways attend erroneous Suppofitions, thefe great
Difcoveries fhould have efcaped the acute Dif
-quifitions of the beft Philofophical Heads of all paft Ages, and be referv’d to thefe our Times. But that wonder will foon ceafe, if it be con-
fider’>d how great improvements Geometry
has receiv’d in our Memory, and particularly
from the profound Difcoveries of our incompa-_
rable Author,
The Theory of the Motion of the pritary—
Planets is here fhewn to be nothing elfe, but the. contemplation of the Curve Lines which Bodies
caft with a given Velocity, in a given Dire@tion, ©
and at the fame time drawn towards the Sun
by its gravitating Power, would defcribe. Or, which is all one, that the Orbs of the Planets
are fuch Curve Lines as a Shot from a Gun de-
fcribes in the Air, being caft according to the dire€tion of the Piece, but bent in a crooked Line by the fupervening Tendency towards the
Earths Centre: And the Planets being fuppofed
to be projected with a given Force, and at-
tracted towards the Sun, after. the. aforefaid mane :
a
ry me ts
— Mifcellanea Curiofa. 1 7
manner, are here proved to defcribe fuch Figures,
® as anfwer punétually to all that the Induftry of this and the laft Age has obferved in the P'ane-
tary Motions. So that it appears, thar there is no need’ of folid’Orbs and Intelligences, as the Antients imagin’d, nor yet of Voreices or Whirl- pools of the Cocieftial Matter, as Des Cartes {up-
" pofes ; but the whole Affair is fimply and me-
chanically performed, upon the fole Suppofition of a Gravitation towards the Sun ; which cannot be denied. | ne ;
~The Motion: of ‘Comets is here fhewn to be
compounded of the fame Elements, and not to _ differ from Planets, but in their greater iwiftnefs,
whereby overpowering the Gravity that fhould hold them to the Sun, as it doth the Planets, they flie off again, ‘and diftance themfelves from the Sun and Earth, fo that they foon are out of our fight. And the imperfect Accounts and Ob-'
_. fervations Antiquity has left us, are not fufiicient
to determine whether the fame Comet ever re-
turn again. But this Author has fhewn how | Geometrically to determine the Orb of a Comet
from Obfervations, and to find his Diftance from
the Earth ‘and Sun, which ‘was never befoie
done. 1%
~The third thing here done is the Theory of the Moon, all the Inequalities of whofe Motion are’ proved io arife from the fame Principles, only here the effect of two Centers operating on, or attracting a projécted Body, comes to be
confidered ; for the Moon, though principally at- _ tratted by the Earth, and moving round it, does
together with the Earth, move round the Sun once a Year, and is, according as fhe is nearer
or farther from the Sun, drawa by him more or lefg than the Center of the Earth, about. ins? ® which
13. Mifcellanea Curiofa. which fhe moves; whence arife féveral Irregu- larities in her Motion, of all which, the Author in this Book, with no lefs Subtility than Indu- ftry, has given a full account... And though by reafon of the great Complication of the Pro- blem, he has not yet been able to make it pure- ly Geometrical, ’tis to be hoped, that in fome farther Eflay he may furmoune the difficulty : And having perfeéted the Theory of the Moon, the long defir’d Difcovery of the: Longitude (which at Sea is only pradticable this way) may at length be brought to light, to the great Ho-. nour of your Majefty, and Advantage of your — Subjeés. | mapa agte!
All the furprifing Phenomena of the Flux and Reflux of the Sea, are in like manner fhewn to proceed. from the fame Principle ; which I defign more largely tovinfitt om, fince the Matter of Faé& is in this Café much bet- ter known to your Majefty than in the fore- . goin . BLE: |
If the Earth were alone, that is to fay, not aflected by the Actions of the Sun and Moen, it is not to be doubred, bur the Ocean, being equally prefsd by, the force of Gravity towards the Center, would continue in a perfect Stagnae tion, always at the fame height, without either Ebbing or Flowing; but it being here demon- {trated, that the Sun and Moon have a like Prin- ciple of Gravitation towards their Centers, and that the Earth is within the Aivity of their At- tractions, ic will plainly follow, that the Equali- ty of the preflure of Gravity towards the Cen- ter will thereby-be difturb’d; and though the fmal!nefs of thefe Forces, in refpeét of the Gravita- _ tion towards the Earth’s Center, renders them al- together imperceptible by any Experiments we
- can
‘
| wget ™
Mifcellanea Curiofa. = 19 can devife, yet the Ocean being fluid and yield- ing to the leaft force, by its rifing fhews where
- itis lefs prefi'd, and where it is more prefs’d by its finking. | |
Now if we fuppofe the force of the Moon’s
Atta€tion to decreafe as the Square of the Di- ftance from its Center increafes (as in the Earth and other Geeleftial Bodies) we fhall find, that where the Moon 1s perpendiculazly either above or below the Horizon, either in- Zenith or Na- dir, there the force of Gravity is moft of all di- minifhed, and confequently that rhere the Ocean ‘mult neceffarily fwell by the coming in of the Water from thofe parts where the Preffure is _ greateft, wiz. in thofe places where the Moon is near the Horizon: But that this may be the bet- - ter underftood, I thought it needful to add the following Figure, (Vide Fig. 1. Plate 1.) where M is the Moon, E the Farth, C its Center, and % the place where the Moon is in the Zenith, N where in the Nadir. |
Now by the Hypothefis it is evident, that the
Water in Z, being nearer, is more drawn by the Moon, than the Center of the Earth Cc, and that again more than the Water in N ; where- fore the Water in Z hath a tendency towards the Moon, contrary to that of Gravity, being equal to the excefs of the Gravitation in Z, a- bove that in C ; And in the other cafe, the Was ter in N, tending lefs towards the Moon than the Center C, will be lefs preffed, by as ‘much as is the difference of the Gravitation towards the Moon inc and N. This rightly underftocd, it follows plainly, that the Sea, which otherwife _ would be Spherical, upon the Preffure of the ‘ Moon, muft form it felf into a Spheroidal or Oval Figure, whofe longeft Diameter is where
hd Cre. the
20 Mifcellanea Curiofa. pis
the Moon is vertical, and fhorteft where fhe iS
in the Horizon ; and that the Moon fhifting her Pofition. as fhe turns round the Earth once a
Day, this Cvalof Water fhifts with her, occa-.
fioning thereby the twe Floods and Ebbs_ obfer- vable in each 25 Hours. " And this may fuffice, as to the general Caufe of
the Tides; it remains now to {Rew how natu-
rally this Motion accounts for all the Particulars that have been obferv’d about them; fo-that there can be no room left to doubt, but that this is the true caufe thereof, :
The Spring Tides upon the New and Fall
Moons, and Neap Tides on the Quarters, are
occafiond by the attractive Force of the Sun in ©
the New and Full, confpiring with the Attracti-
on of the Moon, and producing a Tide by their united Forces: Whereas in the Quarters, the
Sun raifes the Water where the Moon deprefifes ir, and the contrary ; fo as the ‘Tides are made only by the difference of their Attraétions. ‘That the force of the Sun is no greater in this Ca‘e, pro- ceeds from the very fmall Proportion the Senui- diameter of the Earth bears to the vait diftance of the Sun. — | ;
It is-alfo obferv’'d, that ceteris paribus, the fiquinodtial. Spring Tides in March and Sep-
Wr fetus ‘ tes
rember, or near them, are the Higheft, and the
Neap Tides the loweft ; which. proceeds from the greater Agitations of the Waters, when the - Guid Spheroid revolves about a great ‘Circle of the Earth, than when it turns about in a leffer
Circle ; it being plain,*that if the Moon. were
conftituted in the Pole, and there ftocd, that rhe Sphercid would have a fix'd Pofition, and that it would be always high Water under the Poles,
and low Water every where under the AXqui- noétial ;
#
4
a
eg ee Ne ee oe
| Mifcellanea Curiofa. a1
= notial : And therefore the nearer the Moon ap- proaches the Poles, the lefs is the agitation of the
Ocean, which is of all the greatelt, when the
~ Moon is in the Afquinoétial, or farthelt diftant
from the Poles. Whence the Sun and Moon,
being either conjoined or oppofite in the Aiqui-
noctial, produce the greateft Spring Tides ; and
- the fubfequent Neap Tides, being produc’d by
the ‘Tropical Moon in the Quarters, are always the leaft Tides; whereas in Fune and December, the Spring ‘Tides are made by the Tropical Sun
and Moon, and therefore lefs vigorous ; and the
Neap Tides by the A’quinoétial Moon, which
therefore are the ftronger: Hence it happens, that the ditference between the Spring and Neap
Tides in thefe Months, is much le‘$ confiderable
than in March and September. And the reafon why the very higheft Spring Tides are found to be rather before the Vernal and after the Autum-
~ nal Equinox, . viz. in February and Ofober, than _ precifely upon them, is, becaufe the Sun is near-
er the Earth in the Winter Months, and fo comes
to have a greater effect in producing the Tides. » Hitherto we have confider’d fuch Affections
_ of the Tides as are Univerfl, without relation to -
particular Cafes ; what follows from the differing Latitudes of places, will be eafily underftood by | the following Fig. (Vide Fig. 2. Plare 1.) ; Let Ap EP be the Earth cover’d over with very deep Waters, C its Center, P, p, iss Poles,
AE the fequinodtial, F, f, the parallel of La-
titude of a Place, D, d, andther“Parallel-ar equal
diftance on the other fide of the Alquinoétial,
H, hb, the two Points where the Moon is verti- cal, and let K, k, be the great Circle, wherein
the Moon appears Horizontal. It: is evident, , that a Spheroid defcrib’d upon ih, and K ky
C 3 : thal}
29 Mifcellanea Curiofa.
fhall nearly reprefent the Figure of the Sea, and Cf, CD, C.F, Cd, fhall be the heighths of the Sea in the places f, D, F, d, in all which ic is High-water: And leeing that in twelve Hours time, by the diurnal Rotation of the Earth, the Point F is transferr’d tof, and d to D: The height of the Sea CF will be that of the High- water when the Moon is prefent, and Cf that of the other High-water, when the Moon is un- der the Earth: Which in the cafe of this Fi- gure is lefs than the former CF. And in the oppofite Parallel D d, the contrary happens. The Rifing of the Water being always alternately greater and lefs in each place, when it is pro- duc’'d by the Moon declining fenfibly from the fEquinoGtial ; that being the greateft of the two High-waters in each diurnal Revolution of the Moon, wherein fhe approaches neareft either to the Zenith or Nadir of the place : Whence it is, that the Moon in the Northern Signs, in this part of the World, makes the greateft Tides — when above the Earth, and in Southern Signs, when under the Earth ; the Effect being always — the greateft where the Moon is fartheft from the Horizon, either above or below it. And this al- ternate Increafe and Decreafe of the Vides has been obferv’d to hold true on the Coaft of En- gland, at Briftel by Captain Sturmy, and at Ply- mouth by Mr. Colepreffe. |
But the Motions hitherto mentioned are fome-.
what alter’d by the Libration of the Water, — whereby, though the Action of the Luminaries fhould ceafe, the Flux and Reflux of the Sea would for fome time continue : This Conferva- tion of the imprefs’d Motion diminifhes the dif- ferences that otherwife would be between two confequent Tides, and is the reafon why the ; Wesel by cai hae Wbciitone higheft
-—— Mifcellanea Curiofa. 23 highelt Spring-Tides are not precifely on the New and Full Moons, nor the Neaps on the Quar- ters; but generaliy they are the third ‘Tides at. ter them, and fometimes later.
- All thefe things would regularly come to pafs, if the whole Earth were cover’d with Sea very ‘deep; but by reafon of the fhoalnefs of fome places, and the narrownefs of the Streights, by which the Tides are in many cafes propagated, ‘there arifés a» great diverfity in the Effect, and “not to’ be accounted for, without an exact Kaow- ledge of all the Circumftances of the Places, as of the Pofition of the Land, and the Breadth and ‘Depth of the Channels by which the Tide flows ; for avery flow and imperceptible Motion of the wholé Body of the Water, where it is (for Ex- amplé) 2 Miles deep, will fuftice to raifle its Surface vo or 12 Feet in a Tides time; where- as; ifithe fame quantity of Water were to be convey'd up a Channel of 40 Fathoms deep, it would require a very great Stream to effect ir, in fo large Inlets as are the Channel of England, and the. German Ocean; whence the Tide is found to fer ftrongeft in thofe places where the Sea grows narrowelt ; the fame quantity of Wa- ter being to pafs: through a fmaller Paffage : This is moft evident in the Srreights, between Portland and Cape de Hague in Normandy, where the Tide runs like’a Sluce 5 and would be yet more betweén Dover and Ca/ais, if the Tide com- ing about the Ifland from the North did not check: it. And this’ force being once imprets’'d upon the Water, continues to carry it above the level of the erdinary height in the Ocean, par- ticularly where the’ Water meets a direct Ob- ftacle, as it isat St. Malo’s; and where it enters tntova long Channel, which running far ‘into i C 4 the
Sie gt. nee eae | 9540 Be chi
24 Mifiellanes Curiofa.
‘ the Land, grows very ftreight at its Extre- } mity > as it is in the Severn-Sza: at cheatin and \
Briftol. : This fhoalnefs of the Bee, and eas intercurrent _ ; Continents are the reafon,, that in the open Ocean — the ume of High water isnot at ithe Moons ap- — pulfe to the Meridian , but always fonie Hours — after it;.as it is obferv’d upon all the Weft — \Coatt of, ee and Africa, from Ireland to the “Cape of Good-Hope: In all which a.S.W.: Moon — “makes High- al and the fame is reported to. -be on the .Weft fide of America.» But. it would. “be end/efs to account all the particular Solutions, — which are eafie Corollaries of this Hypothefis ; as — why the Lakes, fuch as the Cafpian Sea, and Mediterranean Seas, fuch as the Black Seay. the Streights and, Baltick, haye. no. fenfible ‘Vides.: For Lakes having no ,Comthunication; with the - Ocean, can neither increafe ;nor -diminifh) their ‘Water, whereby to rife and fall; and Seas that communicate by fuch narrow Inkets, and are of fo immenfe an Extent, cannot in a few ‘Hours © lime receive or empty Water enough, to» walle or fink their Surface any thing fenfibly. ; _ Laftly, to demonftrate ” thie Excellency. Fe shis DoGtrine, the Example of the Tidesin the Port of Tunking in China, which are fo extraordinary, and differing from all others we have yet heard of, may fuffice. In this Port’ there is but one — Flood and Ebb in 24, Hours ; and twice imeach Month, viz. When the Moon is near the, FEqui- | noctial there is no Tide at all, but the Water, is ftagnant ; bur with the Moons Declination there begins a Tide, which is greateft when “fhe is. in the Tropical. Signs: Only, with this difference, that when.the Moon. is to the. Northward.of the Aequinodtial, it Flows when) fhe «is “oe the
‘.
— Mifcellanea Curiofa. 25 _the Earth, and Ebbs when fhe is under, fo as to -make High-water at Moons-fetting, and Low- water at’ Moons-rifing: But on the. contrary,
the Moon being to the Southward, makes High-
water at rifing, and Low-water at feiting ; it Ebbing all the time fhe is above the Horizon. As may be feen more 4t large in the Philofophical
Tranfaétions, Numb. 162.
The Caufe of this odd Appearance 1s propos’d
| by Mr. Newzon, to be from the concurrence of two - Tides ; the one propagated in fix Hours out of the great South-Sea aiong the Coalt of China ;
the other. out of the Indian-Sea, from between - the Iflands in twelve Hours, along the. Coaft of Malacca and Cambodia. The one of thefe Tides, being produe’d in North Latitude, is, as has been faid, greater, when the Moon being to the North of the Equator is- above the Earth, and lefs when fhe is under the Earth. ‘The other of them, which is propagated from the Indian Sea, being yaifed in South-Latitude, is greater when the ‘Moon declining to the South, is above the Earth, _and lefs when fhe is under the Earth: So that of thefe Tides alternately greater and leffer, there
comes always fucceflively two of the greater and two of the lefler together every Day; and the
High-water falls always between the times of the arrival of the two greater Floods; and the Low-water between the arrival of the two lef- fer Floods. And the Moon coming to the fEquinottial, and the alternate Floods becoming equal, the Tide ceafes, and the Water flag nates: But when fhe has pafs’d to the other fide
of the Equator, thofe Floods which in the for-
mer Order were the leaft, now becoming the preateft, that “That before was the time of Bigh-watr, naw becomes the Low-water, and
the
26 © Mifcellanea Curiofa. the Converfe. So that the whole appearance of thefe ftrange Tides, is without any forcing — naturally deduced fom thefe Principles, and is a great Argument of the Certainty of the
whole Theory.
bs
| Mifcellanea Curiofa. = 297
> + il: 7 Bi
A Theory of the Variation of
_ the Magnetical Compafs. By
_ Mr. Ed, Halley, Fellow of the Royal Society. | de
wi HE Variation of the Compas. (by which & 1 mean the DefleGion of the Magnetical Needle from the true Meridian) is of that great Concernment in the Art of Navigation, that the neglect thereof, does little lefs than render ufe- lefs cne of the nobleft Inventions Mankind ever yet attained to. And for. this caufe all, Ships of Confequence (efpecially thofe bound beyond. the _ Equator) carry with them Inftruments on pur- pofe to obierve this Variation: ‘That fo the Courle iteer’d by the Compafs, may be reduc’d to the true Courfe in refpect of the Meridian. _. Now although the great utility that a. perfect Knowledge of the Theory of the Magnetical Direétion. would afford to Mankind in. general, and efpecially to thofe concern’d in Sea Affairs, feems as fufficient incitement to all Philofophical and Mathematical Heads, to take under ferious Confideration the feveral Phenomena, and to ene _deayour to reconcile them by fome general Rule : Yet {0 it is; that almoft all the Authors, from whom a Difcourfe of this kind ought to have been expected, pafs by in filence the Difficuliies they here Encounter. And thofe that mention this Variation: By affirming it to proceed from ‘Caufes altogether uncertain (as are the cafual ly-
ing
28 Mifceilanea Curiofa, | ing of Iron Mines and Load{ftones in the Earth) put a ftop to all further Contemplation ; and give difcouragement to thofe that would other- wife undertake this Enquiry. Tis true, that not long fince one Mr. Bond, an old Teacher of Na- vigation, put forth a fmall Treatife, wherein he pretends to calculate the Variation: But he li- mits his Hypothefis to the City of London, affir- ming himfelf (as he had a great deal of reafon) that the fame Calculus is not fufficient for other Places; whereby it appears that this Rule is far fhort of the fo much defir'd general one.
Now although (through want of fafficient Ob- fervations, and fome other Difficulties, which I fhall anon fhew) I cannot pretend perfe&tly to eftablifh the Numbers and Rules of a Calculus, which fhall precifely anfwer to the Variations of all parts of the World: Yet I fuppofe it will noe be unacceptable to the Curious to propofe fome- thing of a Light into this abftrufe Myftery ; which, if no other, may have this good Effect, to ftir up the Philofophical Genii of the Age to apply themfelves more attentively to this ufeful Speculation. But before I proceed, twill be ne- ceffary to lay down the Grounds upon which I raife my Conclufions; and at once to give a Sy- nopfis of thofe Variations, which I have reafon to look upon as fure, being moftly the Obfervations of Perfons of good Skill and Integrity,
peliance saaiah ag
TABLE VARIATIONS.
Names of . |Longitude | Latitude. Ato Varittion Places, from Lon. Dom.\Obferv'd. [4s dm jdm dm
a @.0° 16%.32 NN sv 111s E | . 22}60 E Sik 4.5 E “Oe dat 16721 220 W Paris ae 223 El48 51 N/!683| 430 W “f 1640 ie E
1s 1666 0° oi : | 1681] 220 W Uraniburg 19. o Elgg 54 Nj1672 beg W TE ee eS Cote Copenbagen 12 53 Ejsg gt Nfr649] 1 30 E dee A | 41972] 335 W Dantzick 19 O E54 23 NIi6791 7oOOW Mompelier . 4 0 ae 37 41674] r10 W Brel? 7 4 25 Wi48 23 1680 143 W Rome b 4 13. fe) Eiqr 50 NI 1684) 3 ow Bayonne — 1 20 Wl43 30 N 1680) 120W Fiudfon's Bay 79 40 Wist oo Ni16681915 W
fa Aud. Straights 57 00 WISt 00 Ni1668.29 20 W Ta Baffin’s Bag at ‘Sir Thomas Smith's
So 90 Wi78 Ooo N eed. 00 W Sound |
i
20 Mifcellanea. Curiofa. ‘ 7
Names of Places. Longitude. |Latitude.|Annc Variation.
Dom | a | Coe eae dm: At Sea 50 0 W)38 4o N168:1 7 30 W At Sea + 434 30 Wi43 $0 N'1622] 5 30 W At Sea ‘420 Wht o N167%] 0 40 E Cape St. 4ug.of Brazile 35 30 Wi g 0 $167c] 5 30 EB Cape Frio 44 10 Wle2 49 $167¢h12 Io Be Sea off of theMou. : i 2 | Meh the River Plate $53 °° W39 30 $|x67e|20 33 B At the Baft Entrance of MageDan =e ot 68 00 Wi52 30 S|1670]17 00 EB At theW.Entrance of Milly J the Magellan Straits 75. 90:0N hag 0° ° re oe Baldivia 173,00 Wi40 00 S!1670] 8 Io E At Cape d’ Agulbas [16 30 E34 50 3|1622] 2 co W oe | , 1675| 8 co W At Sea I o E}34 30 $1675) 0 08 At Sea 20 o Wi34 © S|167s|110 30 E At Sea 32 o Wh24 © S}167s110 30 EB At St. Helena 6 0 W{16 00 $1677 0 40 BE At Afcenfion (4 30 WI 7 50 S|1678)| 1 00 :62B At fobanna 44 00 Eii2 15 S!1675|119 30 W At Moubafa 40 00. EB] 4 00 $11675|116 co W At Zocatra ” 56 00 E\i2 30 N!1674]17 co W> Re ln MOBI 50, hg eod|isrdis co W At Diego Roiz 61 © Elo 0 $|1676\20 30 W At Sea 64 30 Elo 6 ]:676l15 30 W At Sea | 35 © EBl27 © $}1676|24 co W At Bombay he 72 30 B19 o N41676]12 00 W At Cape Comorin 76 00 B| 8 15 NPi68c] 8 48 W At Ballafore 87 CO Bl21 30 Nil68&c| 8 20 W
At Fort St. George 80 00 BIF3 15 N4i68c} 8 10 W At theW. Point of Favijtc4 CO EL 6 go 16764 3 10 W
. Mifcellanea Curiofa. 21 Names of Places. |Longitude|Latitude.| Anuo\Variation. Re “ | Dom.
[> ie ee 158 00 Ei39 «0 $11677127 30 W At the Mle of St. Paul |} 72 0 EI38 0 S|\1677|23 30 W At Yan Dimen’s Land |142 © Ef42 25 S1642] 0 0. At New Zealand Avy] U7o..e El4go $0 Si642} 9 o B
A Poe Re Boy 20 the 5 Si6u] # «28
At the ifle Rotterdam 3
_ din the South Sea On theCoaft of N-Guin. Atthe W.P. of N.Guin.
§
184 00 El20 Ig S}1642| 6 20 E
149 00 EB) 4 30 Sj1643 845 8 [26 00 EB] O 26 Si1643) § 30 EB
Tho’ I could with we could obtain from the Spa- miards what Variations they find in their Voyages from the Manilhas towards Acapulco, thorough the North part of the South Sea; as likewife what it is at Fapan from the Dutch: Yet (confidering the num- ber. of thefe Obfervations I have collected, and that they are made in parts of the World fo remote from Europe, and from one another) I fuppofeé that the Theory that anfwers thefe will {cCarce fail in thofe Regions from whence we have as yet no account. But firft we muft make fome Remarks upon the fore- going ‘Table: And, Firft, |
_ That in all Europe the Variation at. this time is Weft, and more in the Eaftern Parts thereof than the-Weftern: As likewife, that it feems throughout ‘to be upon the increafe that way.
. Secondly, That on the Coalt of America, about Virginia, | New-England and New-Foundland, the Vari- ation is likewife Wefterly ; and that it increafes all the way as you go Northerly along the Coaft, fo as ro ‘be above 20 Degrees at New-Found-Land, nearly 30 gr. in Hudfon’s Straights, and not lefs than 57 De- grees in Baffin’s Bay; alfo, that as you Sail Eaft-
ward
32 Mifcellanea Curiofa. ward from this Coaft, the Variation diminifhes. From thefe two it is a Legitimate Corollary: ‘That Somewhere between Europe, and the North part of A- merica, there ought te be an Eafterly Variations or at leaft no Wefterly. And - fovl conjecture it is about the Eaftermoft of the ‘Tercera Ilands. 3 0
re B] BA Laan A satal 2a
Thirdly, That on the Coaft of Brafile there is Eaft Variation, which increafés’ very’ notably: as you go to the Southward, fo as to be 12 Degrees’ at Cape Frio, and over againft the River of P/ate 20% Degrees: And from thence- Sailing South- wefterly to the Straits of Magellan it decreafes 17 Degrees, and at the Weft Entrance bur 14 De-
rees. FS) ¢ ; ; a
Fourthly, That at the Eaftward of Brafile, pros perly fo call’d, this Eafterly Variation decreafes, {6 as to be very little at St. Helena and <Afcenfion, ant to be quite gone, and the Compafs Point true about 18 Degrees of Longitude Welt from:the Cape’ of Good- hope. | eae
Fifthly, That to the Eaftward of the afore+ faid Places a Weltward Variation begins, which Reigns in» the whole Indian Sea, and arifes to no lefs than Eighteen Degrees under the Equa- tor it felf, about the Meridian of the Northera part of Madagafcar; and near the fame. Meri-" dian, but in 39 Degrees South Latitude it is found full.27 4 Degrees: From thence Hafter- ly. the Weft Variation decreafes, fo as to be lit~ tle more than eight Degrees at Cape Comoriny and than three Degrees upon the Coaft of Fe ea; and to be quite extinét about the Melucca
Ifands, as alfo a little to the Weltwards of Van | | } Dimens:
Re RES
aid +, os Pe ack fines!) Sint: Sintet NARA ha
Mifcellanea Curiofa. 33
Diemens ‘Land found out by the Dutch in 1642,
Sixthly, That tothe Eaftward of the Molucca’s _and Van Diemens Land in South Latitude there arifes another Eafterly Variation, which feems . not fo great as the former, nor of fo large Extent ; ~ for that at the Ifland Roererdam it is fenfibly lefs _ than upon the Eaft Coaft of New Guinea; and, at the rate it decreafes, it may well be fuppos’d, that _ about 20 Degrees farther Eaft, or 229 Degrees Eaft Longitude from Londox, in the Latitude of 20 DegreesSouth, a Wetlerly Variation begins.
Seventhly, ‘T’hat the Variations obferv’d by the Honourable Sir Fohn Norborough at Baldivia, and at the Weft Entrance of the Straights of Magellan do plainly thew, that hat Eait Variation, no- ted in our third Remark, is decreafing apace ; and that it cannot reafonably extend many De, grees into the South Sea from the Coaft of Pery and Chili, leaving room for a fimall Wefterly
- Variation, in that Traé&t of the unknown World
that lies in the mid-way between Chili and
New-Zealand, and between Hounds-Ifand and Peru...
Eighthly, That in Sailing North- Weft from
St. Helena by Afcenfion, as far as the Equator, the Variation continues very fmall Eaft, and as it were conftantly the fame: So thar in this part of the World the Courfe, wherein there is no Variation, is evidently no Meridian, but rather
North- Weft.
Ninthly , That the Entrance of Hudfon's Straights, and the Mouth of the River of Pilate, being nearly under the fame Meridian, at the | D one
Mg OA ae SY eae
44 Bi Ne Shy rae Re 34 Mifcellanea Curiofa.
one place the Needle varies 292 Degrees to — the Wt; at the other 202 Degrees to the Eajt.
This plainly demonftrates the impoffibility of: — reconciling -thefe Variations by the Theory of — Bond; which is by two Magnetical Poles and an ~ Axis, -inclin’d to the Axis of the Earth; from whence it would follow, That under the fame Meridian the Variation flould be in all places the — fame way. : a
a”
- Thefe things being premifed may ferve as a
fure Foundation to raife the Superftru@ture of a Theory upon. But firft it would not be amifs — to fhew hereby the miftake of Gilbert and Des — Cartes: The firft whereof fuppofes ; that the Earth it felf being in all its parts Magnetical, and the Water not; wherefoever the Land is, thither alfo fbould the Needle turn, as to the greater quan- tity of Magnetical Matter. ° But this in many In- {tances is not true; but moft remarkably up- - on the Coaft of Brazile, where the Needle: is fo far from being attra€ted by the Land, that it turns the quite contrary way, leaving the Meridian to lye N b E, which is juft along the Coaft. As to the Pofition of Des Cartes, that the Tron and Loadftones hid in the Bowels of the Earth and the Bottom of the Seay may be the Caufes that the Needle varies ; if we confider for how great a part of the Earths Surface, ex gr. in the whole Indiaz Sea, the Needle declines the fame way, and that regularly, ’twill follow that the _attracting Subftance that occafions it, muft be very far diftant. Now by Experience we find the little force that Iron Guns have upon the Compafs in Ships (their Vertue, though they be Demiculverin, or greater Cannon, being not ‘perceptible at four or five Yards diftance) a | the
ee Me Mifcellanea Curiofa. - 35 the Experiments now before the Royal Society do plainly fhew, how little a Magnetifm there #8 in moft crude Jron Oars: What quantity _ thereof muft be then fuppos’d to make fo power- ful a Diverfion at two or three Thoufand Miles - diftance ? Yet I cannot deny that in fome places
near the Shoar, or in Shoal-Water, the Needle . _ may be irregularly direéted from the aforefaid - Caufeés, and that not a little, as Gaffendus gives a motable inftance of the Ifland E/ba in the Me- diterranean Sea: But thefé-difierences from the general Direction are always figns of the near- nefs of thofé Magnetical Subftances, for the Pro- dudtion whereof that Ifland E/ba has been famous from all Antiquity. Befides, againft both Des Cartes and Gilberz, the change of the Variation, _ which has been within thefe Hundred Years laft _ paft more than 19 gr. at London, is an‘entire De- monftration ; tho’ Des Cartes does not ftick to fay, that the tranfportation of Iron from place to _ place, and the growth of new Iron within the _ Earth, where there was none before, may be the caufe thereof. The fame holds likewife againft the Hypothefis of Magnetical Fibres, which Kircher
maintains. '
Now to propofe fomething that may anfwer the feveral appearances, and introduce nothing ftrange in Philofophy, after a great many clofe _ Thoughts, I can come to no other Conclufion than that, The whole Globe of the Earth is one great Magnet, having four Magnetical Poles, or Points of Attraétion, near each Pole of the Equator Two; and that, in thofe parts of the World which fie near adjacent to any one of thofe Magnerical
Poles, the Needle is govern'd thereby, the neareft Pole being always predominant over the more re~ _ mote, ‘Yhe parts of the Earth wherein thefe et: | D 2 * Mag-
(360 = Mifcellanea Curiofa.
Magnetical Poles lie, cannot as yet be exactly.
determia’d for want of fufficient Data to pro- ceed Geometrically ; but, as near as Conjecture can reach, I reckon that the Pole, which is at _ prefent neareft to us, lies in or near the Meri- dian of the Lands-end of England, and not a-
bove feven Degrees from the Pole Arétick ; by
this Pole the Variations in all Europe and Tartary, and the North Sea are principally governd, though with regard to the other Nothern Pole,
whofe fituation is in a Meridian pafling about.
the middie of California, and about 15 gr. from the North Pole of the World; to this the
eS. co ali e parahahsz:
Needle has chiefly refpeét in all the North 4- —
merica, and in the two Oceans on either fide thereof, from the Azores Weltward to Fapan, and farther. ‘The two Southern Poles are ra- ther farther diftant from the South Pole of the World: The one about fixteen Degrees there- from, is in a Meridian, fome twenty Degrees to the Weftward of Magellan Straights, or ninety five Degrees Weft from London: This com- mands the Needle in all the Soush-America, in
the Pacifick Sea, and the greateft part of the ~
Ethiopick Ocean. ‘The Fourth and laft Pole feems to have the greate{t Power, and largeft Dominions of all, as it is the moft remote from
the Pole of the World, being little lefs than
20 Degrees diftant therefrom in the Meridian,
which pafles through Hollandia Nova, and the —
Ifland Celebes about one hundred and twenty De- grees Eaft from London this Pole is predomi«
nant in the South part of Africa, in Arabia and —
the Red Sea, in Perfiay Indias and its Iflands, and all over the Indian Sea, from the Cape of
” Good-Hope Eaftwards to the middle of the great South Sea, that divides Af from America. ‘This feems
BAY.
Mifcellanea Curiofa. — 37 feems to be the prefent Difpofition of the Mag- ‘netical Vertue throughout the whole Globe of the Earth; it remains to fhew how this Hypo- thefis makes our all the Variations that have been obferv’d of late; and how it anfwers to our feveral Remarks drawn from the Table. And firft it is plain, that (our European North Pole being in the Meridian of the Lands-end of England) all places more Eafterly than that will have it onthe Welt fide of their Meridian, and confequently the Needle, refpecting it with its Northern’ Point, will have a Welterly Variati- on, which will ftill be greater as you go to the Eaftwards, till you come to fome Meridian of Ruffia, where ’twill be greateft, and from thence decreafe again. “Thus at Bre/? the Variation is but 13 Degrees, at London 4x Degrees; but at Danizick feven Degrees Weft. ‘To the Welt- ward of the Meridian of the Lands-end, the Needle ought to have an Eafterly Variation ; were it not that (by approaching the American Northern Pole, which lies on the Welt fide of _ the Meridian, and feems to be of greater force than this other) the Needle is drawn thereby _ Weftwards, fo as to counterbellance the Di rie€tion given by the European Pele, and to make — a fmall Weft Variation in the Meridian of the Lands-end it felf. Yet I fuppofe that about the - Meridian of the Ifle Tercera, our neareft Pole _ may fo far prevail as to give the Needle a litte
turn to the Eaft, though but fot a very {mall {pace : The Counterballance of thofe two Pol-s _ permitting no confiderable Variation in all the _ Eaftern Parts of the Atlantick Ocean; nor up- on the Weft Coatts of England and Treland, France, Spain and Barbary. But to the Weft-
wards of the Azores the Power of the American eae D 3 [ Pole
: 2 : ne byte 2 tk eee i yy Mifcellanea Curtofa, =
Pole overcoming that of the European, the Needle — has chiefly. refpect thereto, and turns ftill more f and more towards it as you approach it. Whence — it comes to pafs, that on the Coaft of Virginia, — New-Eng! and, New-found-Land, and in Hudfon’s« ‘ , Straights the Variation is Weftward ; that it de- — creafes as you go from thence towards Europe, — and that ic is lefs in Virginia and New-England, — than in New-found-Land, and Hudfon’s-Straights. — This Wefterly Variation again decreafes, asyou pafs over the North America; and about the — Meridian of the middle of California the Needle - again points due North; and from thence Welt- ward to Yedzo and Fapan, Imake no doubt but ~ the Variation is Eafterly, and half the Sea over — no lef than fifteen Degrees, if there be any © truth in this Hypothefis of mine. Therefore I — propofe this as a Trial, that the whole may be © {cann’d thereby ; and I conceive it will not be © hard to know of the Spaniards how it is, who fo — frequently. fail through that Ocean, in their re- — turn from the Manilba Ifles. "This Eaft Variation — extends over Japan, Yedzo, Eajft-Tartary, and part of China, till it meet with the Weftere — ly, which -is govern’d by the European North | Pole, and which 1 faid was greateft fome where — in Ruffia. : : ae cn "Towards the Southern Pole the effect is much — the fame, only that here the South Point. of © the Needle is attraéted. Hence it will follow, — that the Variation on the Coalt, of Bragile, at — the River of Plate, and fo. on to the Straights — of Magellan, fhould be Eafterly (as in our third — Remark) ; if we fuppofe a Magneticul Pole fitu- — ate about twenty Degrees more Welterly than
the Straights of Magellan. And this Eafterly Va- — ‘riation doth extend Eaftward over the greatelt — | | | ‘part
ir .
a cis tana a ta
Mifcellanea Curiofa: 39, part of the Erhiopick Sea, till it be counterpor fed by the Vertue of the other Southern Pole 3
as it is about mid-way between the Cape of Good- .
wx:
Hope, and the Ifles of Triftan d Acuntia. From
_- thence Eaftwards, the <Afien South Pele (as I ~ muft take the liberty to call it) becoming pre=
valent, and the South point of the Needle be- ing attracted: thereby, there arifesa Welt Vari-
ation, very great in quantity and extent, be-
caufe of the great diftance of this Magnetical
~ Pole of the World. Hence it is, that in allthe Indian Sea as far as Hollandia Nova, and farther,
there is conftantly Weft Variation ; at that un- der the Equator it felf it arifes to no Jefs than eighteen Degrees, where “tis moft. About the Meridian of the Ifland Celebes, being likewife that of this Pole, this Wefterly Variation ceafés, and an Eafterly begins; which reaches, accor- ding to my Hypothefis, to the middie of the © South-Sea, between Xelandia Nova, and Chili, leaving room for a fmall Wt Variation govern’d
by the American South Pole, which I fhew’d to be in the Pacifick Sea, in the fixth and feventh Remark. :
_ What I have now faid, does plainly fhew the
fufficiency of this Hypothefis for folving the Va-
_ riations that are at this time obferv’d in the tem-
perate and frigid Zones, where the Direétion of
_the Needle chiefly depends upon the Counterpoife of the forces of two Magnetical Poles of the
fame Nature; and I fuppofe I have fhewn how
it comes to pafs, that under the fame Meridian the Variation fhould be in one place 291 Welt,
and another 202 Eaft ; as I have noted in my
_ ninth Remark. |
In the Torrid Zone, and particularly under the Equinodtial, refpect muft be had to all four ‘gee -D 4 Poles,
40 Mifcellanea Curiofa. ~ Poles, and their Pofitions well confider’d, others wife it will not be eafie to determine what the
Variations fhall be ; the neareft Pole being al- ways the ftrongeft; yet not fo, as not to be
-counterballanc’d fometimes by the united forces —
of two more remote ; a notable Inftance where- of is in. our eighth Remark, where I took
notice, that in failing from St: Helena by the
Ile of <Afcenfion, to the Equator, on a N. WM Courfe, the Variation is very little Eafterly,
EN THe SY
and in that whole Traé& unalterable ; for which
I give this Reafon, That the South American Pole ee is confiderably the neareft in the aforefaid Places) requiring a great Eafterly Va- - fiation, 1s counterpoifed by the contrary At- traction of the North-American and the Afian- South*Pole; each whereof fingly are ia thefé Parts, weaker than the American-South-Pole ; and upon the North Weft Courfé, the Diftance from this latter is very little varied ; and as you re- cede from the Afian-South-Pole, the Ballance is ftill preferv’d by the accefs towards the North- American-Pole. I mention not in this Cafe the European-North-Pole, its Meridian being little re-
Pe
mov'd from thofe of thefé places; and of it felf .
requiring the fame Variations we here find.
After the fame manner we tight proceed to —
conclude the Variations in other places under
and near the Equator ; but I purpofely leave it for an Exercife to the Thoughts of the ferious — Reader, who is defir'd to help his Imagination,
by having before him a Map or Globe of the
Earth: And ta mark thereon the Magnetical Poles in the Longitudes and Latitudes | aflign them. (Vide Plate 2.) wears es ee
Thus
SiR eine RE
™ ‘9
Mifeellanea Curiofa. 4
Thus, I hope, I have not loft my Pains and Study in this difficule Subje&t ; believing that I have put it paft doubt, That there are ix the Earth four fuch Magnetical Points nr Poles, which occafion the great variety and feeming ivregit- larity which is obferv’d in the Variations of tke Compafs. But to calculate exactly what it is,
“in any place affign’d, is what I dare not yet
pretend to, though I could wifh it were my hap- pinefs to be able to oblige the World with fo
ufeful a piece of Knowledge ; there are Difi- culties that occur, that render the thing as yet.
not feafible; for firft there are a great many
_ Obfervations requifite, which ought to be made
at the fame time ; not at Sea, but afhore, with greater Care and Attention than the generali-
ty of Sailors apply. And befides, it remains
undetermin'd in what proportion the attractive Power decreafes, as you remove fronf the Pole of a Magnet, without which it were a vain
attempt to go about to calculate. There is yet a further Difficulty, which is the Change of the
Variation, one of the Difcoveries of this laft Century ; which fhews, that it will require {ome hundreds of Years to eftablifh a compleat De- &trine of the Magnetical Syftem. From the
foregoing Table ic fhould feem, that all the _ Magnetical Poles had’ a motion Weltward :
ns
But if it be fo, ’tis evident, that it is not a Ro-
tation about the Axis of the Earth ; for then the Variations would continue the fame, in the fame parallel of Latitude (the Longitude only
_ chang’d) as much as is the motion of the Mag-
_ Variation of eleven Degrees Eaft at this time ;
netical Poles, but the contrary is found by Ex-
perience ; for-there is no where in the Latitude
of 15z North between England and America, a
as
\
x i. Tee at oy
4.2 Mifcellaniea Curiofas ~ 4 as it was once here at London ; it feems therefore, that our European Pole is grown nearer the Pole | Arfick than it was heretofore, or elfe that it has loft part of its Vertue. But whether thefe Mag- netical Poles move altogether with one motion, or with feveral ; whether equally or unequally a whether Circular or Libratory : If Circular, a-— bout what Center ; if Libratory, after what man-— ner; are Secrets as yet utterly unknown to Man-— kind, and are referv'd for the Induftry of future | Ages. 4 9 = 7 4a
iad m EOE AA ee OK A TE ate
: , ) )itite ee ee a ee
Pry hey Oar
Mifcellanea Curiofa. | 42
‘An Account of the Caufe of the Change
© of the Variation of the Magne-
tical Needle, with an Flypothefis of the Structure of the Internal _ Parts of the Earth ; as it was pro- pofed to the Royal Society in one of their late Meetings, By Mr. Edmund Halley. T Aving in, the precedent Difcourfe deli- vered a Theory of the Variation of the
~Magnetical Compafs, wherein I did colle& as
many Obfervations as at that time I could procure, and having carefully compar’d them
‘together, I came at length to this general
conclufion, That the Globe of the Earth might be fuppofed to be one great Magnet, having four
Magnetical Poles or Paints of Attraétion, near
each Pole of the Equator two 5 and that in thofe parts of the World which lie near adjacent to any one of thofe Magnetical Poles, the Needle .is chiefly govern d thereby 5 the neareft Pole being al- ways predominant over the more remote. And I there have endeavour’d to ftate and limit the prefent Pofition of thofe Poles in the Surface of
our Globle, .which the Reader pleafing to con-
fult, will fave us the pains of repeating. Buc
after all, tho’ that Difcourfe was favourably
‘receiv'd both at home and abroad, as feeming to render a tolerable account of the obferv’d Hn Variations ©
PEARS: let
Ad Mifcellanea Curiofa. Variations, yet I found two Difficulties not eafie to furmount; the one was, that no Magnet 1 had ever feen or heard of, had more than two” oppofite Poles, whereas the Earth had vifibly ; four, and perhaps more. And fecondly, it was _ plain that thefe Poles were not, at leaft all of them, fixt in the Earth, but fhifted from place to place, as appear’d by the great Changes in the Needles Direétion within this laft Century of — Years, not only at London, (where this great Difcovery was firft made) but almoft all over the Globe of Earth; whereas it is not known or obferv’d that the Poles of a Load-ftone ever — fhifted their place in the Stone, nor (confider-— ing the compaé hardnefs of that Subftance) can, it eafily be fuppos’d; though the Matter of F ack be too notorious and univerfal, not to be ac- — counted for. a Thefe Difficulties had wholly made me de- fpond, and I had long fince given over an In-— quiry I had fo little hopes of, when in accidental — Difcourfe, and leaft expe&ting it, I ftumbl’d on — the following Hypothefis ; in delivering where- of, if I fhall feem to advance any thing that looks like Extravagant or Romantick, the Rea- der is defir’d to fufpend his Cenfure, till he have — confider’d thé force and number of the many — Arguments which concur to make good fo new — and fo bold a Suppofition. 203 te ae ~ ‘Though it be fufficiently known and allow’d, — that the Needles Variation changes, it will be neceffary however to give a few Inftances, whereby it may appear that this Change is gra~ dual and univerfal, and the effeét of a great and “permanent motion : For which take the follow. —
ing Examples. / | ap
ne ae Seis om ; e eds
aan
bs Ure 2 i
ay
— — Mifcellanea Curiofa. 45 At London, in the Year 1§80, the Variation was obferv'd by Mr. Burrows to be 119 15! Eaft. In Anno 1622, the fame was found by Mr, Gun- ter to be but 6° of Eaft, Inthe Year 1634, Mr. Gellibrand found it 4° 5! Eaft. In 1657, Mr. Bond obferv’d that there was no Variation at London. Anno 1672, my felf obferv’d it 2° 30! to the Weft; and in the Year 1692, I again found it 6° oof Weft. So that in 112 Years the Directi- on of the Needle has chang’d no lef than feven- teen Degrees, i | At Party Orontius Fineus about the Year 150, did account it about eight or nine Degrees Eaft Variation. _ Anno 1640, it was found three De- trees Eaft. Anno 1660, there was no Variati- there, and Anno 1681, I found it to be 2° 30° to the Weft. | :
At Cape d@’ Agulba, the moft Southerly Pro- montary of Africa, about the Year 1600, the Needle pointed due North and South without Va- -Yiation, whence the Portugueze gave its name. Anno 1622, there was two Degrees Weft. Vari- ation. Anno 1675, it was 8° 50! Welt ; andin the Year 1691, it wascurioufly obfery’d not lefs than eleven Degrees Welt.
At St. Helena, about the Year 1600, the Needle declin’d eight Degrees to the Eaft. An- no 1622, it was but 6° of Eaft. Anno 1677, when I was there, I obferv’d it accurately on Shoar to be 0°. go! Eaft ; and in 1692 it was found about 1° to the Weftward of the North.
__ At Cape Comorine in India, in the Year 1620, there was 14.° 20! Weft Variation. Inthe Year 1680, there was 8° 48!, but now lately in the Year 1688, it was no more than 7° 30/, fo that here the Needle has return’d to the Fatt about (e- ven Degrees in feventy Years.
5 Io
46 Mifcellanea Curiofa. — i In all the other Examples the Needle has gra- dually mov’d towards the Welt, and the places — are too far afunder to be influencd by the re-_ moval of any Magnetical Matter, which may by accident be tranfplac’d within the Bowels, or "on the Surface of the Earth. If more Examples are defir’d, the Reader may be furnifh’d with them in the Portugueze Routier of Aletko de Mot- ra (written about the Year 1600) and in the Voyage of Beaulieu, both publifh’d’ in Mr. The- venot’s firft ColleGtion of curious Voyages, Prin- ted at Paris, Anno 1662 ; which he isto com- pare with the Journals of our late Eaf? India Voyagers, and I am affur'd, that it will be there- by evident, that the Dire€tion of the Needle is in no place fix’d and conftant, ‘tho’ in fome it change fafter than in others: And where for a long time’ it has continu’d as it were unalter’d, it is there to be underftood, that the Needle has its grea- teft Deflection, and is become Stationary in or- der to return, like the Sun, in the Tropick. This, at prefént, is in’ the Indian-Sea, about the Ifland! Mauritius, where is the higheft Weft Variation, and in a Tract tending from thence into the N. N. W. towards the Red-Sea and Egypt. And in all Places to the Weftward of this T'ra&t, all over Africa and the Seas adjoin- ing, the Weft Variation will be found to have encreas'd ; and to the Eaftwards thereof, as in the Example of Cape Comorine, to have decreas | fed, viz. all over the Ea/t-Indies, and the Iflands near ite + Mea : After the like manner in that Space of Eat. Variation, which, beginning near St. Helena, is found all over the South America, and which at prefent is higheft about the’ Mouth of Rio de la Platay-it has been obferv’d, that in the Eaftern Parts.
Mifcellanea Curiofa. 47 Parts thereof, the Variation of the Needle gra~ dually decreafes; but whether on the contrary it increafes in thofe places which lie more We- ‘fterly than that Tra wherein the higheft Eaft Variation is found ; or how it may be in the valt Pacifick Sea, we have not Experience e= nough to afcertain, yonly wemay by Analogy in- fer, that both the Fait and Weft Variations there- in do gradually increafe and decreafe after the fame Rule.
Thefle Phenomena being well underftood and duly confider’d, do fufltciently evince, ‘That the whole Magnetical Sy{tem is by one, or perhaps more motions tranflated, whether Eaftwards or Weftwards, I fhall anon difcufs ; that this mo- ving thing is very great, as extending its effects from Pole to Pole, and that the motion thereof is not per faltum, but a gradual and regular motion. | | te
Now confidering the Structure of our Terra- queows Globe, it cannot be well fuppos’d that a very great part thereof can move within it, without notably changing its Center of Gravi- ‘ty and the Equilibre of its Parts, which would produce very wonderful Effects in changing the Axis of diurnal Rotation, and occafion ftrange alteration in the Seas Surface, by Inundations and Recefles thereof, {uch as Hiftory never yet mentiond. Befides, the folid parts of the | Earth are not, to be granted permeably by any other than fluid Subftances, of which we know
mone that are any ways Magnetical. So that the only way to render this motion intelligible and poffible, is to fuppofe it to turn about the Center of the Globe, having its Center of Gra- vity fix’d and immoveable in the fame common Center of the Earth: And there is yet requir’d, Gi | | : that
Se tr ae " Sean
of by Tee Gag as 4
48 Mifceilanea Curiofa. 4q that this moving internal Subftance be loofe and detached from the external Parts of the Earth whereon we live ; for otherwife, were it affhix’d thereto, the whole muft neceffarily move together. ..
.
So then the External Parts of the Globe may well be reckon’d as the Shell, and the Inter-— nal as a Nucleus or inner Globe, included with-" in ours, with aluid Medium between, which having the fame Common Center and Axis of — diurnal Rotation, may turn about with our Earth — each twenty four Hours; only this outer Sphere having its turbicating motion fome fmall matter either fwifter or flower than the internal Ball: And a very minute Difference in length of time, — by many Repetitions becoming fenfible, the In- ternal Parts will by degrees recede from the External, and not keeping pace with one ano- ther, will appear gradually to move either Eaft- wards or Weftwards by the difference’ of their motions. | .
Now fuppofing fuch an Internal Sphere hae ving fuch a motion, we fhall folve the two great Diffculties we encounterd in my former Hy- thefis: For if this exteriour Shell of Earth be a Magnet, having its Poles at a diftancefromthe — Poles of diurnal Rotation; and if the Internal Nucleus be likewife a Magnet, having its Poles in two other places, diftant alfo from the Axis; and thefe latter by a gradual and flow motion change their place in refpect of the External ; we may then give a reafonable account of the four Magnetical Poles I prefume to have demon- {trated before ; as likewifejof the Changes of the Needles Variations, which tat now hath been un- attempted. ; | ji
Mifcellanea Curiofa. 49 ~» The Period of this Motion being wonderful ‘great, and there being hardly an hundred Years fince thefe Variations have been duly obferv’d, dt will be very hard to bring this Hypothefis to
a Calculus, efpecially fince, though the Varia- stions do increafe and decreafe regularly in the fame place, yet in differing places, at no great _ diftance, there are found fuch cafual Changes thereof as can no ways be accounted for by a regular Hypothefis; as depending upon the un- ‘equal and irregular diftribution of the Mag- “netical, Matter within the Subftance of the Ex- ‘ternal Shell or Coat of the Earth, which de- ‘fle& the Needle from the Pofttion it would ac- quire from the effect of the general Magnetifm of the'whole. Of this the Variations at Lendon ‘and Paris give a notable Inftance, for the Needle bas ‘been conftantly about 1° more Eafterly at Paré than at London; though it be certain that according to the general effect, the Difference ought to be the contrary way : Notwithftanding which, the Variations in both places do change alike. 3 : Hence, and from fome other of like Nature, A conclude, That the two Poles of the External Globe are fixt in the Earth, and that if the _ Needle were wholly govern’d by them, the Va- ‘riations thereof would be always the fame, with ‘fome littleMrregularities upon the account I but syuft now mention’d: But the Internal Sphere “having fuch a gradual tranflation of its Poles, does influence the Needle, and direct it vari- oufly, according to the refule of the attractive or directive Power of each Pole ; and confe- quently there muft be a Period of the Revolu- -tion of this Internal Ball, after which the Va- -Fiations will retura again as before, But if. it ae vans GL E fall
50 Mifcellanea. Curiofa. fhall in future Ages be obferv’d otheiwifé, we muft then conclude that there are more of thefe Internal Spheres, and more Magnetical Poles — than Four, which at prefent we have not a fuf- ficient number of Obfervations to determine, - and particularly in that vaft Mar del-Zur, which — occupies fo great a part of the whole Surface of the Earth. : 4 CORE yt 2 of If then two of the Poles be fixt and two. move-— able, it remains to afcertain which:they are that keep their place ; and though I :could wifh we had the Experience of another Century, of Years to found our Conclufions upen, yet I think we -may fafely determine, That our European North Pole (which in the precedent Difcourfe I fuppos’d near the Meridian of the Lands-end of England, and about feven Degrees therefrom) is that That is moveable of the two Northern Poles, and that That has chiefly influenc’d the Variations in thefe parts of the World: For in Hudfon’s Bay, which is under the DireCtion of ‘the American Pole, the Change isttot obferv’d to be near fo faft.as in thefe parts of Europe, though that Pole be much farther rremov'd from the Axis, 1 bop .ogart am As to the South Poles, I take: the Afian Pole, which '1 place about the Meridian of the Ifland Celcbes to be the fixt, and confequently the Aimee rican Pole to move ; from the like Obfervation of the flow Decreafe of the Variation on the Coaft of Fava, and near the Meridian of the Afian - Pole ; thovgh I muft confefsto have no-account of the effects of the other, beyond Magellan’s’ wBtreients. 17, a, * . dot Tiivole If this be allow’d me, ’tis plain that the fixe Poles are the Poles of this- &xternal Shell or Cortew of the Earth, and the other two the Poles of a Magnetical Nucleus included’ and moveable
Mifcellanea Curiofa. 51 moveable within the other. It likewife follows, that this Motion is Weitwards, and by confe- quence that the aforefaid Nucleus has not precife- ly attained the fame degree of Velocity with the extertour Parts in their diurnal Revolution ; but fovery nearly equals it, that in 365 Revolves the the difference is fcarce fenfible. ‘This I conceive’ to arifé from the Impufe whereby this diuraal Motion was impreft on the Earth, being given to the External Parts, and from thence in time com- municated to the Internal ;. but not {0 as perfe&- ly to equal the Velocity of the firft Motion im- prefsd on, and ftill conferv’d by the fuperficial Parts of the Globe. As to the quantity of this Motion it is al- moft impoffible to define it, both from the’ Na- ture of this kind of Obfervation, which can- not be very accurately perform’d, as alfo from the fmall time thefe Variations have been ob- ferv’d, and their Change difcover’d. It appears by all Circumftances, that its Period is of ma- ny Centuries of Years, and as far as may be col- leG&ted from the Change of the Place, where there was no Variation, by reafon of the Equi- libre of the two Southern Magnetical Poles, viz, from Cape d’ Agulhas to the Meridian of St. Hele- na (which is about 23 degr. in about ninety Years) and of the place where the Wefterly Variation is in its ¢xun or greateft Deflection, being a- bout half fo much, viz. from the Ifle of Diego Roig to the South Weft Parts of Madagafcar. We may with fome Reafon conjecture, that the American Pole has mov’d Weftwards forty fix Degrees in that time, and that the whole Period thereof is perform’d in feven hundred Years, or thereabouts ; fo that the nice Determination of this, and of feveral other Particulars in the
| E 2 -Magnetick
Jiald ee ' Ph wort a
52 Mifcellanea Curiofa. - Magnetick Syftem is referv’d for remote Pofteri- ty ; all that we can hope to do, is to leave be- © hind us Obfervations that may be confided in, ~ and to propofe an Hypothefis which after Ages may examine, amend or refute. Only bere Imuft take leave to recommend to all Mafters of Ships, — and all others, Lovers of Natural Truths, that they ule their utmoft Diligence to make, or pro= cure to be made, Obfervations of thefe Variati- ons in all parts of the World, as well in the North — as South Latitude (after the laudable Cuftom of our Ea/t India Commanders) and that they pleafe to communicate them to the Royal Society, in or-— der to leave as compleat a Hiftory as may be to thofe that are hereafter to compare all together, and to compleat and perfect this abftrufe The- ory. | ‘dy F And by the way it will not be amifs to a-— mend a receivd Error in the Praétice of ob=_ ferving the Variation, which is, to. take it by” the Amplitude of the Rifing and Setting Sun,’ when his Center appears in the vifible Ho= rizon ; whereas he ought to be obferv’d when’ his under Limb is {till above: the Horizon a>: bout 3 of his Diameter, or twenty Minutes,’ upon the {core of the Refra€tion, and the height’ of the Eye of the Obferver above the Surface of the Sea: Or elfe they are to work the Amplitudes as they do the Azimuth, reckon-- ing the Suns Diftance from the Zenith go%! 36! : This, though it be of little confequence nesr the /Eiquinoétial, will make a great Error io high Latituzes, where the Sun rifes and fers obliquely. ae Ee | But to return to our Hypothe&s, In order ta. explain the Change of the Variations, we have adventur’d to make the Earth hollow, and to. : place
-
UP anid Mie le Dia i?
Mifcellanea Curiofa. 52 place another Globe within it; and 1 doubt no® - but this will find Oppofers enough. I know *ewill be Objected, ‘That there is no Inftance in Nature of the like thing ; that if there was fuch a middle Globe it would not keep its place in the Center, but be apt to deviate therefrom, and might poflibiy chock againit the Concave Shell, to the ruin, or at leaft endammaging thereof ; That the Water of the Sea would per- petually leak through, unlefs we fuppofe the Ca- vity full of Water; That were it poflible, yet it does not appear of what ufe fuch an inward Sphere can be of, being fhut up in Eternal Dark- nefs, and therefore unfit for the Produétion of Animals or Plants; with many more Objedti- ons, according to the Fate of all fuch new Pro- -pofitions. | 3 To thefe, and all other that I can forefee, I briefly Anfwer, ‘That the Ring environing the Globe of Saturn is a notable Inftance of this kind, as having the fame common Center, and moving along with the Planet, without fenfibly approaching him on one fide more than the o- ther. And if this Ring were turm’d on one of its Diameters, it would then defcribe fuch a Concave Sphere as I fuppofe our External one to be. And fince the Ring, in any Pofition given, would, in the fame manner, keep the Centre of Saturn in its own, it follows, that fuch a Concave Sphere may move with another included in it, having the fame common Cen- tre. Nor can it well be fuppos’d otherwife, confidering the Nature of Gravity; for fhould thefe Globes be adjufted once to the fame com- mon Centre, the Gravity of the parts of the Concave would prefs equally towards the Cen- tre of the inner Ball, which equality muft necef- 7 E 3 {arily
Sa { 3 kona 0 aes ayye :
54 Mifcellanea Curiofa,° farily continue till fome External Force difturb — it, which is not eafie to imagine in our Cafe. — This perhaps I might more. intelligibly exprefs, by faying that the inner.Globe being pofited in — the Centre of the Exteriour, muft neceffarily af-_ cend which way foever it move; that is, it muft — overcome the force of Gravity prefling towards ;
v4
the common Centre, by an impulfé it muft re-. ceive from {ome outward Agent ; but all outward Efforts being fufficiently fenc’d againft by the Shell that furrounds it, it follows, that this Nu- cleus being once fixt in the common Centre, muft always there remain. 3 ae As to the leaking of the Water through this Shell, when once a paffage fhall be found for it — to run through, I muft confefs it 1s an Obje€ti- on feemingly of weight; but when we confider — how tightly great Beds of Chalk or Clay, and ~ much more Stone do hold Water, and even — Caves archd with Sand; no Man can doubt f but the Wifdom of the Creator has provided © tor the Macrocofm by many more ways than 7; %
i ye i ¢
oy
-can either imagine or exprefs, efpecially fince we — fee the admirable and innumerable Contrivan- — ces wherewith each worthlefs Individual is fur-— nifh’d both to defend it felf, and propagate its — Species. What Curiofity in the Strudture, what — Accuracy in the Mixture: and Compofition of © the parts, cught not we to expect in the Fabrick — of this Globe, made to be the lafting Habita- tion of fo many various Species of Animals, in each of which there want not many Inftances — that manifeft the boundlefs Power and Goodnefs of their Divine Author ; and can we then think ~ it a hard Suppofition, that the Internal Parts of this Bubble of Earth fhould be replete with’ fuch Saline and Vitriolick Particles as may Con= — | tribute —
Mifeellanea,Curiofa. 55. tribute to Petrefaction, and difpofe the tranfuding - Water to fhoot and coagulate into Stone, fo as continually to fortifie, and, if need were, to con- folidate any breach or flaw in the Concave Surface And this perhaps may not without Reafon be fuppos'd to be the final Caule of the admixture of the Magnetical Matter in the Mafs of -the. Terreftrial parts of our Globe, viz. "To make good and maintain the Concave Arch of this. - Shell: For by what the Excellent Mr, Newson, has fhewn in his Principia Philofophie, it will fol- low, that according to the general Principle of Gravity , vifible throughout the whole Uni- verfe, all thofe Particles that by length of time, or otherwife, fhall moulder away, or become. loofe on the Concave Surface of the External Sphere, would fallin, and with great force de- {cend on the Internal, unlefs thofe Particles were of another fort of Matter capable by their ftron- ger tendency to each other, to fufpend the force of Gravity ; but we know no other Subftances capable of fupporting each other by their mutu- al Attraction but the Magnetical, and thele we fee miraculoufly to perform that Office, even where the Power of Gavity has its full effeG, much more within the Globe where it is weaker. Why then may we not fuppofe thefe faid Arches ro be lin’d throughout with a Magnetical Mat- ter, or rather to be one great Concave Mag- net, whofe two Poles are the Poles we have be- fore. obferv’d to be fixt in the Surface of our _ Another Argument, favouring this Hypo- thefis, is drawn from a Propofition of the fame Mr., Newton, where he determines the force wherewith the Moon moves the Sca in produ- ge 4 cing
56 — Mifeellanea Cariofa,
ing the Tides : His Words are, Déenfitas Luna eft — ad denfitatem Terre ut 680 ad 387 feu 9 ad 5 quamproxime. Eft igitur corpus Lune denfius ace i. magis terrefire quam Terra noftra, p. 466, Now a if the Mcon be more folid than. the Earth, as 9 to
5, why may we not reafonably fuppofe the Moon,
being a {mail Body, .and a fecondary Planet, to — be folid Earth, Water, Stone, and this Globe to — confift of the fame Materials, only ‘four Ninths thereof to be Cavity, within and between the — Internal Spheres; which I would render not im- ie
probable.
To thofe that fhall enquire of what ufe thefe
included Globes can be, it muft be allow’d,
_ that they can be of very little fervice to the In
habitants of this outward World, nor can ‘the, - Sun be ferviceable to them, either with his Light or Heat. But fince it is now taken for granted, that the Earth is one of the Planets,
and they all are with Reafon fupposd Habitable,
though we are not able to define by what. fort (
of Animals; and fince we fee all the parts’ of the Creation abound with Animate. Beings, as the Air with Birds and Flies, the Water with the numerous. varieties of Fifth, and the ae f 3
Earth with Reptiles of. fo many forts; all
whofe ways of Living would be to us incredible did not daily Experience teach us. ‘Why then
Should we think it ftrange that the prodigious
Mafs of | ‘Matter, whereof this Globe does con- —
ff, fhould be capable of fome other improve-
ment than barely to ferve to fupport its Sur-
face ?. Why may not we rather fuppofe that the exceeding {mall quantity of folid Matter, in rer
fpe&t of the fluid Aither, is fo difpos'd by the Almighty Wifdom, as to yield as great a Sur 3 face for the ule of living Creatures, as can con- ’
goo “fit
Mifcellanea Curiofa. 59 {sft with the conveniency and fecurity of the whole? We our felves, ‘in Cities where we are preffed for Room, commonly build many Stories one over the _ other,” and thereby accommodate a much greater multitude of Inhabitants. But ftill it will be faid, That without Light there can be no no living, and therefore all this Apparatus of our inward Globes muft be ufelels : To this 1 Anfwer, That there are many ways of producing Light which we are wholly ignorant of; the Medium it feif may be always luminous after the manner of our Ignes fatui. ‘The Con- cave Arches may in feveral places fhine with fucha Subftance as invefts the Surface of the Sun ; mor can we, without a boldnefs unbecoming a Philofopher, adventure to aflert the impoffibility of peculiar Luminaries below, of which we have no fort of Idea... Lam fure the Poets Virgil and Claudian have gone before me in this ‘Thought, inlightning their E/yfian Fields with Sun and Stars proper to thofe infernal, or rather internal Re- gions. Virg. Aneid.6.
| Largior hic compos ther 3 lumine veftit® ~~ Purpureo , Solemque fuum fua Sidera norunt,
And Claudian lib 2. De Raptu Proferping.
> Amiffum ne cirede diem, funt altera nobis Sidera, funt orbes alii, luménque videbis “Pirius, Elsfiumque magis mirabere Solem.
_ And though this be not to be efteem’d as an Ar- gument, yet ] may take the liberty I {ee others do, to quote the Poets when it makes for my
| purpufe, hs :
Laftly,
AVioS. ‘ey > raw COME See
58 — Mifeellanea.Curiofa, =
‘
~ Laftly, To explain yet farther what I mean, I have adventur'd to adjoin the following Scheme, (Tab. 1. Fig. 3) wherein the Earth is reprefented,
of Earth, and all the Arches more. than fufficient-_ ly {trong -to bear their weight..."The Concave’ of each Arch, which is. fhaded differently from the reft, I fuppofe to be made up of Magnetical Matter ; and the whole to, turn about the fame common Axis p, p, only with this difference, that the Outer Sphere ftill moves fomewhat — fafter than’ the Inner. ‘Thus, the, Diameter of — the Earth being about eight thoufand Englifo, Miles, 1 allow five hundred Miles. for the thick- nef of its Shell, and another. fpace of five hun- dred Miles for a Medium between, capable of - an immenfe Atmofphere for the ufe of the Globe of Venus: Venus again I give a Shell of the, fame thicknefs, and leave as great a fpace be-— tween her Concave and Mars ; fo likewife from Mars to Mercury, which latter Ball we will fup-— pofe folid, and about two thoufand Miles Dia-— meter. Thus I have fhew’d a poffibility of a much more ample Creation, than has hitherto been imagin’d ; and if this feem ftrange to thofe that are unacquainted with the Magneti- cal Syftem, it is hop’d thar all fuch will endea-— vour, firft, to inform themfelves of the Mat- ter of Fad, and then try if they can find out a more fimple Hypothefis, at leaft a lefs ab-_ ‘furd, even in their own Opinions. . And where-— as -1 bave adventur’d to make thefe Subterrane- ous Orbs capable of being Inhabited, *twas done _ defignedly for the fake of thofe who will be apt tol
Gp sae
Mifcellanea Curiofa. 59 to ask cui bono, and with whom Arguments drawn from Final Caufes prevail much. If this fhort Effay fhall find a kind Acceptance, I fhall be en- courag’d to enquire farther, and to Polith this ~ rough Draft of a Notion till hitherto not fo much as ftarted in the World, and of which we could have no Intimation from any other of the Phens- mena of Nature. — , | Since this was written, a Difcovery I have made in the Coeleftial Motions, feems to render a farther Account of the Ufe of the Cavity of the Earth, viz. To diminifh the Specifick Gravity thereof, in refpect of the Moon; for I think I can demonftrate that the Oppofition of the Ate ther to the Motions of the Planets in long time becomes fenfible ; and confequently the greater Body mutft receive a lefs Oppofition than the fmaller, unlefs the Specifick Gravity of the fmal- ler do proportionably exceed that of the greater, “gn which cafe only they can move together ; fo thar the Cavity I affign in the Earth, may well - ferve to adjutt its weight to that of the Moon, for otherwife the Earth would leave the Moon behind it, and fhe become another Primary Planet.
An
1 is
ee 43
ee
#
| Mifcellanea Curiofa. 6%
An Hiftorical Account of the ‘Trade _ Winds and Monfoons, obferva- ble in the Seas between and near the Tropicks, with an attempt to affign the Phyfical Caufe of the | faid Winds, by Mr. Ed. Halley.
ALN exaé& Relation of the conftant and pe- riodical Winds, obfervable in feveral Traéts of the Ocean, is a part of Natural Hi- ftory not lefs defireable and ufeful, than ir is difficult to obtain, and its Phenomena hard ,to explicate: I am not ignorant that feveral Wri- ters have undertaken this Subject, and although Varenius (Lib. 1. Chap. 21. Geo. Gen.) feems to have endeavour’d after the beft information from Voyagers, yet cannot his Accounts be ad- mitted for accurate, by thofe that fhall atten- tively confider and compare them together, and fome of them are moft evident Miftakes ; which, as near as I can, I fhall attempt to rectify, having had the opportunity of converfing with | Navigators, acquainted with all parts of In- diay and having liv’d a confiderable time be- tween the Tropicks, and there made my own Re- marks. | : The Subftance of what I have collected is — briefly as follows. - , The Univerfal Ocean may moft properly be divided into three Parts, viz. 1, The <Atlan- tick and LEthiopick-Sea. 2, The Indian Ocean. | 3. [he
pith hry gi
63 Mifcellanea Curiofa. : 3- The Great South Sea, or the Pacifick Ocean ; — -and though thefe Seas do all communicate bythe. South, yet as to our prefent purpofe of the Trade — Winds, they are fufficiently feparated by the ine — terpofition of great Tracts of Land 3 the firft ly- — ing between Africa and America, the fecorid be= tween Africa and the Indian Ilands, and Hollandia — Nova ;,and the laft between the Phillipine Iles, — ' China, Fapan and Hollandia Nova on the Weft, and the Coaft of America on the Ea. Now fol- lowing this natural divifion of the Seas, fo will — we divide our Hiftory into three parts in the © fame order. |
I. In the <Arlantich and Aithiopickh Seas be- — tween the Tropicks, there is a general Eafterly Wind all the Year long, without any confider-— able Variation, excepting that it is fubje& to be deflected therefrom, fome few Points of the Com- pafs towards the North or South, according to the Pofition of the place. ‘The Obfervations which have been made of thefe Deflections, are the following. i 4, That near the Coaft of 4frica, as foon as you have pafs’d the Canary Ifes, you are fureto’ meet a frefh Gale of North Eaft Wind, about the Latitude of 28 Degrees North, which feldom comes to the Eaftwards of the Eaft North-Eaft, or paf- festhe North NortheEaft. ‘This Wind accompa-— nies thofe bound to the Southward, to the Lati- tude of ten North, and abouta hundred Leagues from the Guinea Coaft, where, till the fourth — Degree of North Latitude, they fall into the Calms and ‘Tornadoes; of which more here-— after. Cyt on) ae
a 2. That
Mifcellanea Curtofe. 63 _.2, That thofe bound to the Caribbee Ifes, find, as they approach the American fide, that the afore- faid North-Eaft Wind becomes ftill more and more Eafterly, fo as fometimes to be Ea/t, fome- times Eajt by South, but yet moft commonly to the Northward of the Eaffa Point or two, feldom
more. °Tis likewife obferv'd, that the ftrength tor thefe Winds does gradually decreafe, as you fail to the Wegwards.
' 3. That the limits. of the Trade and vari. able Winds, in this Occan, are farther extend- ed onthe American fide than the African; for. whereas you meet ‘not with this certain Wind till after you have pafsd. the: Latitude of twen- ty eight Degrees on,this fide ; on the American fide it commonly holds to thirty, thirty one, or thirty two Degrees of Latitude; and this is verified likewife to the Southwards of the A- quinoétial, for near the Cape, of Good:Hope the limits of the Trade Winds, are three or four Degrees nearer the Line, than on the Coait of eBraztles, -- : ri
4 That from the Latitude of four Degrees
North, ‘to the aforefaid Limits on the South
of the-AZquator, the Winds are generally and
perpetually between the South and Eaft, and
-moft commonly between the South-Eaft and
Eft, obferving always this Rule, That on the
African fide they are more Southerly, on the
Brazilian more Eafterly, fo as to become almoft
due Eaf, the little defleion they have being iftill to the Southwards.. In this part of the
Ocean it ‘has been my fortune to pafs a full
Year, in an Employment that oblig’d me to ree
—gatd rhore than ordinary the Weather, and I
found the Winds conftantly about the South-
« Eaft, the moft ufual Point S$ £bE; when it
ewod ie Was
64 Mifceilanea Curiofa. was Eafterly, it generally blew hard, and. was gloomy, dark, and fometimes rainy ‘Weather 5 if it came to the Southwards’ it was generally Serene, and a {mall Gale next to a Calm, but this not very common. But I never faw it to the Weftwards of the South, or Northwards of the Eaft. 5. That the Seafon of the Year tas Mote final effet on thefe Trade Winds, for that when the Sun is confiderable to the Northwards of — the /Equator, the South-Eaft Winds, efpecially in the Straight of this’ Ocean (if I'may fo- call it) between Brazile ‘and ‘the Coat of Gui- nea, do vary a Point or two) to’ the Southwards, and the North-Eaft become more Eafterly ; and on the contrary, when the Sun is towards the Tropick of Capricorn the South-Eafterly Winds become miore Eafterly, and the North-Eafterly_ Winds on this fide the, Line veere more to shee Northwards. i
6. That as there is no peitetal: Rule that ade mits not of fome Exception, fo there is in. this Ocein a Tra& of Sea wherein the Southerly and South-Weft Winds are perpetual, wiz. all along the Coaft of Guinea, for above five hun- dred Leagues together, from Sierra Leona to. the Ifle of St. Thomas ; for the South:Eaft Trade Wind having pafs’d the Line, and approach- ing the Coaft of Guinea within eighty or 100 Leagues, inclines towards the Shore, and: be- comes S.S.E. and by Degrees, “as you’ come nearer, it veeres about to South, S.S. W. and Gn with the Land South-Weft, and “fometimes ‘Weft South-Weft; which Variation is better ex- prefs’d in the Mapp hereto annexed, (Vide Plate 2.) than it can well be in Words. - Thete are the Winds which are obferv’d on this Coaft when it
Mifcellanea Curiofa. 68 blows true, but there are frequent Calms, vio- De fudde n Gukts call’d Tornado’s, from all Points of the Compafs, and fometimes. unwholfome fog-
gy Eafterly Winds, call’d Hermitaa by the Na- tives, which too often infeft the Navigation of
thefe parts. ’
7. That to the Northwards of the Line, . be- _ tween four and ten Degrees of Latitude, and be-
tween the Meridians of Cape Virdey and of the
Eafterntoft Ifiands that bear that Name, there is
a Tract of Sea wherein it were improper to fay
there is any Trade Wind, or yet a Variable ;
for it feems condemn’d to perpetual. Calms, at-
_ tended with terrible Thunder and Lightning, and Rains fo frequent, that our Navigators .from thence call this part of the Sea the Rains; the little Winds that are, be only fome fidden un- certain!;Guifts; of very. little Continuance and ~ JefS Extent; fo that fometimes each Hour you fhall have a different Gale, which dies away into a Calm before another fucceed, and ina Fleet “of Ships in fight of one another, each hall have the Wind from a feveral Point of the Compafs;
— with thefe weak Breezes Ships are oblig’d to make ‘the belt of their way to the Southward through the aforefaid fix Degrees, wherein ‘lis repcried fome have been detain’d whole Months for want of Wind.
From the three laft Obfervables is fhewn the -Reafon of two notable Occurents in the Ea/?- India and Guinea Navigations: The one is,
w hy, notwithftanding the narroweft part of the
Sea between Guinea and Brazile be aboot five
‘hundred Leagues over, yet Ships bound to the Southward, fometimes, efpecially in the Months _
of Fuly and Auguft, find a great difficulty to
pals it, This happens becaufe of the Southe ie F | Eatt
ly extending fome Degrees beyond the ordinary
limit of four Degrees North Latitude, and with- al they come fo much Southerly, as to be fome- -
J a
hi:
i
SR
times South, fometimes a Point or two to the
Welt ; there remains then only to ply to Wind-
ward, and if on the one fide they ftand away
W.S. W. they gain the Wind ftill more and
more Eafterly ; but there is danger of not wea-—
thering the Brazilian Shoar, or at leaft the Shoals —
upon that Coaft. But if upon the other Tack
they go away E. S.E. they fall into the Neigh-
bourhood of the Coaft of Guinea, from which there is no departing without running Eafterly,
as far as the Ifle of St. Thomas, which is the con- ftant praétice of all the Guinea Ships, and which
may feem very ftrange, without the confidera- tion of the fixth Remark, which fhews the Rea-
fon of it: For being in with the Coaft, the Wind blows generally at S.W. and W.S. W.
with which Winds they cannot go to the North-
ward for the Land; and on the other T'ack they
can lie no nearer the Wind than S. S. E. or
South ; with thefe Courfes they run off the Shoar, but in fo doing they always find the Winds more and more contrary; fo that when
near the Shoar they could lie South, at a greater _ diftance they can make their way no better than 'S. E. and afterwards E.S. E. with which Courfes they fetch commonly the Ifle of St. Thomas and
Cape Lopez, where finding the Winds to the Faft-_ ward of the South, they keep them favourable, by running away to the Weftward in the South
Latitude, of three or four: Degrees, where the S. E, Winds are perpetual. _ wy For the fake of thefe general Winds, all thofe that ule the 772t-Indian Trade, even thofe | bound
ae Sas ena ae <
| Mifcellanea Curiofa. 67 bound to Virginia, count it their, beft Courfe to get as foon as they can to the Southwards, that fo they may be certain of a fair and frefh Gale to run before it to the Weftwards ; and for the fame Reafon thofe homewards bound from Ame= rica, endeavour to gain the Latitude of thirty Degrees, as foon as poflible, where they firft find the Winds begin to be variable; tho’ the moft ordinary Winds in the Northern part of the Atlantick Ocean come from between the South and Welt. | As to thofe furious Storms call’d Hurricaness which are, as it were, peculiar to the Caribbee Iles; and which fo dreadfully affli& them in the Month of Auguft, or not much before of after, they do not fo properly belong to this place, both by Reafon of their fmall continu- ance and extent, as likewife becaufe they aré not Anniverfary, {ome Years having more than one, and formetimes for feveral Years together there being none at all. But their Violence is fo unconceivable, and. their other Phenomena fo furprifing, that they merit well to be confider’d apart.
_ What is here faid, is to be underftood of the Sea Winds at fome diftance from the and ; for upon and near the Shoars, the Land and Sea Breezes are almoft every where fenfible ; and the
_ great Variety which happens in their Periods, Force and Direction, from the fituation of the Mountains, Vallies and Woods, and from the various Texture ‘of the Soil, more or lefs capas ble of retaining and reflecting Heat, and of exe haling or condenfing Vapours, is fuch, that it were an endlefs task, to endeavour to account for them. |
68 Mifeellanea Curiofe. ;
‘a IJ. Inthe Indian Ocean, the Winds are part- : ly general, as in the Achiopick Ocean, partly™ Periodical ; that ts, halfthe Year they blow one § way, and the ‘other ‘half near upon the oppo- fite Points; and thefe Points and ‘Times of — fhifting are different in different parts of this Oseuh® ; the limits of each Traét of Sea, fubje& to the fame Change or Monfoon, are certainly” very hard to determine, but the diligence I have _ ufed to be rightly inform’d, and the care I have taken therein, has, in a great meafure, fur-— mounted that Difficulty; and I am perfwaded - that the following Particulars may be relied , upon. : 1. That between the Latitudes of ten De grees and thirry Degrees South, between Ma= dagafcar and Hollandia Nova, the ” general Trade Wind atout the §. E. by E. is found to blow all the Year long, to all Intents and Purpofes_ after the fame manner as in the fame Latitudes in the Zthiopick Ocean, as it is deferib’d i in the fourtty Remark aforegoing. ay Thar'the stored tt, Annies bade to. within two Degrees of the Aquator, during the Months of Sunes Fuly, Augufl, &c. to Novem- ber, at which time between the South Latitudes of three and ten Degrees, being near the Meri- dian of the North end of Madagafcar, and be- tween two and twelve South Latitude, being near Sumatra and Fava, the contrary Winds from the N. W. or between the North and .Weft, fet in and blow for half the Year, viz. from the be- ginning of December till May; and this Monfoon is obferv'd as far as the Molucca Ifles, of whic more anon. ;
a. /1p a
iD) a
oy. 3S
MifcellaneaCwiofa. 69 3. That tothe Northward of three Degrees South Latitude, over the whole Arabian or
Indian-Sea and Gulph of Bengall, from Sumatra to the Coatt of Africa, there is another Mon- foon, blowing from O&sber to April upon. the North Eaft Points; but in the othey half Year, from April to Ofober, upon the oppofite Points of S, W. and W.S. W. and that with rather more force than the other, accompanied with
~dark rainy Weather, whereas the N. E. blows clear ; °tis likewife to be noted, that the Winds are not fo conftant, either in firength or poict in the Gulph of Bengall, as they are in the In- dian-Sea, where a certain and fteady Gale f{carce ever fails. "Tis alforemarkable, that the S$. W. Winds in thefe Seas are generally more Souther- ly on the 4fricgn fide, more Weilerly on the Indian, | :
| 4 That as an Appendix to the laft detcrib’d Monfoon, there is a Tract of Sea to the South- wards of the Aiquator, fubjec&t to the fame Changes of the Winds, viz. near the African= Coaft, between it and the Ifland Madagafcar or St. Lawrence, and from thence Nor:hwards as far asthe Line ; wherein from April to Octcber there is found a conftant frefh §.S. W. Wind, which, as you go more Northerly, becomes
‘ftill more and more Wefterly, fo as to fall in
with the W. S. W. Winds, mention’d before, in, thofe Months of the Year to be certain to the Northward of the Aiquator : What Winds blow in thefe Seas, for the other half Year, from
Oftober to April, 1 have not yet béea able to obtain to my full fatisfaion, for that our
- Navigators always return from India without
Madagafcar, and {fo are little acquainted in this
Matter ; the Account that has teen given me is
| ae ra only
DRY oe oe Be
JO Mifcellanea Curiofa, q only this, that the Winds are much Eafterly here- abouts, and as often to the North of the true Eaft | as to the Southwards thereof. | 5. That to the Eaftward of Sumatra and — Malacca, to the Northwards of the Line, and along the Coaft of Camboia and China, the — Monfoons blow North and South, that is to fay, the N. E. Winds are much Northerly, and the S. W. much Southerly: This Conftitution reaches to the Eaftwards of the Philippine Iles, and as far Northerly as Fapan. ‘The Northern Monfoon fetting in, in thefe Seas, in Oéober or November, and the Southern in May, blowing all the Summer Months: Here it is to be no. ted, That the Points of the Compafs, from — whence the Wind comes in thefe Parts of the World, are not fo fixt as in thofe lately de- {crib’d ; for the Southerly will frequently pafs a Point or two to the Eaftwards of the South, and the Northerly as much to the Weftwards of the © North, which feems occafion’d by the great quantity of Land, which is interfpers’d in thefe Seas. | - 6. That in the fame Meridians, but to the Southwards of the A.quator, being that Tra& — lying between Sumatra and Fava to the Weft, and New Guinea to the Eaft, the fame Norther- — ly Monfoons are obferv'd, but with this diffe- rence, that the inclination of the Northerly is | towards the N. Weft. and of the Southerly to- _ wards the S. E. but the plage venti are not more conftant here than in the.former, viz. variable © five orafix Points ; befidés the times of the Change of thefe Winds, are not the fame as in the Chinefe Seas, but about a Month or fix Weeks — later, hy oe he ‘os hal
“9, That
ae i i Sc SRR, <i. Re oe ee aes fae See SR ames
PIS RIES Nee > OS
ts ee Se
= ites * Se oe SS
BSR Aa
eee ese ee
\ ie
Mifcellanea Curiofa. Ji. 7. That-thefe contrary Winds do not fhift all at once, but in fome places the time of the Change is attended with Calms, in others with variable Winds ; and it is particularly remarkable, that the.end of the Wefterly Monfoon on the Coaft of Coromandel, and the two laft Months of the Southerly Monfoon in the Seas of China, are very fubjeét to be tempeftuous : The violence of thefe Storms is fuch, that they feem to be of the Na- ture of the 7/t-India Hurricanes, and render the Navigation of thefe parts very unfafe about that time of the Year. ‘Thefe Tempefts are by our Seamen ufually term’d, The breaking up of the Monfoons. | By reafon of the fhifting of thefe Winds, all thofe that fail in thefe Seas, are oblig’d to ob- ferve the Seafons proper for their Voyages, and fo doing they fail not of a fair Wind and fpeedy Paffage ; but if fobe they chance to out-ftay their time, till the contrary Monfoon {ets in, as it free quently happens, they are forc’d to give over the
~ hopes of accomplifhing their intended Voyages,
and either. return to the Port from whence they
came, or elfe put in tofome other Habour, there
to {pend the'time till the Winds fhall come fa- vourable, 3 |
+ Ul. The third Ocean call’d Mare Pacificum,
whofe Extent is equal to that of the other two (it being from the Weft Coaft of America to the
Philippine lands, not lefs than 150. Degrees, of
Longitude) is that which is leaft known to our
own or the Neighbour Nations; that. Naviga=
tion that there is on it, is by the Spaniards, who go Yearly from the Coalt of New Spain to the Manilha's, but that but by one beaten track; fo that I cannot be, fo particular here as in the ee ee ge eee
On eS pe
92 = Mifeellanea’ Curiofa.
other two, What the Spanifb Authors fay of the | Winds they find in their Courfes; and’ what is” confirm’d by the old Accounts of Drake and Cans difhs and fince by Schooten, who fail’d the whole — breadth of. this Sea in the Southern Latitude of i fifteen or fixteen Degrees, is,’ that there is a great conformity between the Winds of this Sea, and thofe of the Arlantickh and Atrhiopick ; ‘that 1s to” fay, that to the Northwards of the: FEquator, the predominant Wind is between the Eaft and North-Eaft, and to the Southwards thereof there is a asnitine’ fteady Gale between the Eaft and South-Eaft, and that on ‘both fides the Line” with fo much conftancy, that they fcarce ever _ need to attend the Sails, and Strength, that it~ is rare to fail of crofling this vaft Ocean in ten Weeks time, which is about 120 Miles per | diem ; befides, “tis faid that Storms and’ Tem-. pelts : are never known in thefe parts: So that here is the very beft of Sailing ; no want of a frefh fair Wind, and yet no danger of having too much : Wherefore fome have thought it might be as fhort a Vo rage to Fapan and Chi- na, to go by the Stre ipl of Magellan, as by the Cape of Good Hope. j | ; The Limits of thefe general Winds igi aie ~much the fame as in the Azlantick Sea, viz. about the thirtieth Degree of Latitude on’ both fides; for the Spaniards homewards bound from the Manilha’s, always take’ the els of the Southerly Monfcon,, blowing there int Summer Months, and run up to the North- wards of that Latitude, as high as Fapan, be- fore they mect with variable Winds, to fhape theic Courfe to the Eaftwards. And Schooren and others that have. gone about by ‘the Magel-_ lan —— have found the Limits of S. E. Wines
Mifcellanea Curiofa. 73 Winds, much about the fame Latitude to the
uthwards; befides a farther Analogy between. the Winds of this Ocean, and the 4thiopick, ap= pears in that, upon the Coaft of Peru, they are always much Southerly, like as they are found near the Shoars of Angola. OP te Thus far Matter of Fact, wherein if the in- formation I have receiv’d he not in all parts ‘Accurate, it has not been for want of inquiry
from thofe I conceiv'd beft able to inftru& me ;
and I fhall take it for a very great Kindnefé if any Mafter of a Ship, or orher Perfon, well in-
form’d of the Nature of the Winds, in any of
the aforemeation’d parts of the World, fhall pleafe to communicate their Obfervations thcre- upon’; fo that what I have here Collected may be either confirm’d or amended, or by the ad-
_ dition of fome material Circumftances enlarg’d.
It is not the work of one, nor of few, but of a multitude of Obfervers, to bring together the Experience requifice to compofe a perfect and
-compleat Hiftory of thefe Winds ; however I
am not much doubtful that I have err’d in, or “omitted any of the principal Obfervables, what-
ever leffer Particulars may have efcaped my
Knowledge. _ | To help the Conception of the Reader in a manner of fo much difficulty, I believ’d it necef-
fary toadjoin a Scheme, (Plate x.) fhewing at
‘one view all: the various Traéts and Courfes of thefe Winds ; whereby ‘tis pofliblé the thing may ‘be better under{tood,: than by any verbal Defcrip- tion whatfoever.
- ‘The Limits of thefe feveral ‘Tra@ts are. de-
. fign’d every where by pricke Lines, as well in
‘the Arlantick and Aithiopick, where they are - ‘the boundaries of the Trade and variable Winds,
as
ite
A yy
74 Mifcellanea Curiofa.. as in the Indian Ocean, where they alfo thew the Extent of the feveral Monfoons. I could think of no better way to defign the Courfe of - the Winds on the Map, than by drawing rows — of ftroaks in the fame Line that a Ship would move going always before it; the fharp: end of — each little ftroak pointing out that part of the Horizon, frem whence the Wind continual- ly comes; and where there are Monfoons, the — rows of the ftroaks run alternately backwards _ and forwards, by which means they are thicker there than elfewhere. As to the: great South — Sea, confidering its vaft Extent, and the little Variety there is in its Winds, and the great Analogy between them, and thofe of the Atlan-— tick and thiopick Oceans 3 befides, that the greateft part thereof is wholly unknown to us; Ithought it unneceflary to lengthen the Map therewith. Sho ae Soh a ee In the foregoing Hiftory are contained feve-— ral Problems, that merit well the Confidération © of our acuteft Naturalifts, both by reafon of the — .conftancy of “the Effect, and of the immenfe Extent thereof; near half the Surface” of the Globe ‘being concerned. The chief of thefe Problems are, 1. Why thefe Winds» are’ perpe- fually from the’ Eaft in the Arlantick and Athio= pick, as likewife in the Pacifick Ocean, between the Latitudes of 20 North and South ? 2. Why — the faid’ Winds:extend no farther with conftan- — cy than to the Latitudeof 30 Degrees ?... 35 Why there fhould be a conftann South-wefterly; Wind — upon and nearthe Coaft of Guinea? 4¢ Why — inthe North part of the Indian Oceanythe Winds, — which for one half Year do agree, with thofe of — the cther two Oceans, fhould .change in.\the,.o- ther half. Yéar, and -blow!, from the .eppofie
Points 5
¥
aaa oe
| Mifcellanea,Curiofa. 75
Points ; whilft the Southern part of that Ocean: follows the General Rule, and has perpetual Winds about S, Ee? §. Why in thefe General Trade-
Winds it fhould be always true, that to the Northward of the 4quator it is inclin’d to the Northwards of the Eaft; and in South, Latitudes, to the Southward théreof ? 6. Why in thefe Seas of China there fhould be fo great an Inclination ‘from the Eaftto the North, more than elfewhere ? with many more, which it would be much eafier to propofe than anfwer.
- But left I fhould feem to propofe to others, Difficulties which I have not thought worth my own Time and Pains, take here the refulr of an earneft Endeavour after the true reafon of the aforefaid Phenomena ; wherein if I am not able to account for all Particulars, yet *tis hoped the Thoughts I have fpent thereon, will not be judged wholly loft, by the Curious in Natural Enquiries.
Wind is moft properly defined to be the Stream or Current of the Air, and where fuch. a Current is perpetual and fixt in its Courfe, ’tis neceflary that it proceed from a permanent un- intermitting Caufe, Wherefore fome have been inclin’d to propofe the diurnal Rotation of the Earth upon its Axis, by which, as the Globe turns Eaftwards, the loofe and fluid Particles of the Air, being fo exceeding light as they be, are left behind, fo that in refpe& of the Earths Surface they move Weftwards, and become a conftant Fafterly Wind. ‘This Opinion feems ' confirm’d, for that thefe Winds are found only “neat the 4quinoétial, im thofe Parallels of Lati- » tude where the diurnal Motion is fwiftelt ; and ] fhould readily affent to it, if the conftant Calms in the Arlansick Sea, near the 4quator,
he the
ea
96 Mifcellanea Curiofa.
‘Aiquator in the Indian Seas, did not declare the”
Tote, ae eae 7 }
the Welterly. Winds near the Coaft of Guinea ‘if and the Periodical Wefterly Monfoons under the
infuffiency of that Hypothefis. Befides the Air be- ing kept to the Earth by the-Principle of Gra- wity, would acquire the fame degree of Velocity that the Earths Surface moves with, as well ia refpect of the diurnal Rotation, as of the Annu-— al about the Sun, which is about thirty times fwifter. | ]
It remains the1efore to fubftitute fome other ~ Caufe, capable of producing a like conftant Ef-—
fe&, not liable to the fame Objections, but a- —
agreeable to the known Properties of the Elements § of Air and Water, and the Laws of the Mo- — tion of fluid Bodies. Such ai one is, I conceive,
‘the Adction of the Sun Beams upon the Air and —
Water, as he paffes every Day over the Oceans, — confider’d together with the Nature of the Soil, — and Situation of the adjoining Continents : I. fay therefore, firft, that according to the Laws — of Sraticks, the Air which is lefs rarified orl expanded by heat, and confequently more pon- — derous, muft have a Motion towards thofe
parts thereof, which are more rarified, and lefs ponderous, to bring it to an Aquilibrium 3 and — fecondly, That the Prefence of the Sun conti- nually fhifting to the Weftwards, that part to-— wards which the Air tends, by reafon of the —
ipa
’ RarifaGtion made by his greateft Meridian Heat, —
is with him carried Weftward, and confequently — the tendency of the whole Body of the lower — Air is that way. Sigua a
“Thus a general Eafterly Wind is formed, —
which being imprefled upon all the Air of a vaft Ocean, the Parts impel one the other, and fo — keep moving till the next return of the Sun, —
i. whereby —
= See
— Mifcellanea Curiofa. 77 whereby fo much of the Motion as was loft, is again reftored, and thus the Wefterly Wind is made cay eiitier as : From the fame Principle it follows, that this Eafterly Wind fhould on the North fide of the Equator, be to the Northwards of the Eaft, and in South Latitudes to the Southwards thereof ; for near the Line, the Air is much more rarified, than ata greater diftance from it; becaufe of the Sun twice in a Year Vertical, and at no _time diftant above 23 Degr. and ahalf ; at which diftance the Heat, being as the Sine of the An- gle of Incidence, is but little fhort of that of the perpendicular Ray. VVhereas under the | Tropicks, though the Sun ftay long Vertical, yet he is as long 47 Degr. off ; which is a kind of Winter, wherein the Air fo cools, as that the Summer-heat cannot warm it to the fame de- gree with that under the A‘quator. Wherefore the Air to the Northwards and Southwards, be- _ ing lefs rarified than that in the middle, it fol- lows, that from both fides it ought to tend to- — wards the A‘quator: ‘This Motion compounded with the former Eafterly Wind, anfwers all the Phanomena of the general Trade-winds ; which, if the whole Surface of the Globe were Sea, would undoubtedly blow all round the World, as they are found to do in the Arlantick and Athio- pick Oceans. : But feeing that fo great Continents do inter- pofe, and break the continuity of the Oceans, _ segard muft be had to the Nature of the Soil, and the Pofition of the high Mountains, which T fuppofe the two principal Caufes of the feve- . tal Variations of the Winds, from the former - general Rule: For if a Country lying near the Sun, prove to be flat, fandy, low Land, fuch as
gS SE LE a er rc , eee Mg! Ss RO , Ms
78 Muifcellanea Curiofa. ; as the Defarts of Lybia are ufually reported to be, the Heat occafion’d by the Reflection of the Suns Beams, and the retention thereof ia the Sand, is incredible to thofe that have not felt it; whereby the Air being exceedingly rarified, it 5 neceffary that the cooler and more denfe Air fhoud run thitherwards to reftore the Aguilibrium: This I take to be the caufe, why near the Coaft of Guinea the Wind always fets in upon the Land, blowing Wefterly inftead of Eafterly, there be= ing fufficient Reafon to” believe, that the Inland Parts of Africa are prodigioufly hot, fince the Northern Borders thereof were fo intemperate, as_ to give the Ancients caufe to conclude, that all be- yond the Tropick was made uninhabitable by excefs of Heat: From the fame Caufe it happens, that there are fo conftant Calms in that part of the O- cean, called the Rains, (defcribed in the 7th Remark on the Atlantick Sea) for this Traét being placed in the middle, between the Wefterly Winds blow= ing on the,Coaft of Guinea, and the Eafterly ‘Trade- winds, blowing to the Weftwards thereof, the tendency of the Air here, is indifferent to either, and fo ftands in Aquilibrio between both; and the weight of the incumbent Atmofphere being diminifhed by the. continual contrary Winds blowing from hence, is the reafon that the Air here holds not the copious Vapour it receives, but lets it fallinto frequent Rains. ~ aM _ But as thecool and denfe Air, by reafon of its greater Gravity, prefles upon the hot and rarifi- ed, ’tis demonftrative that this latter muft afcend in a continued Stream as faft it rarifies ; and that being afcended, it muft difperfe it felf to preferve the Aguilibrium: that is, by aconttary Current, the upper Air muft move from thofe Parts where _ the greateft Heat is; So by a kind of city, _ the
ys
Mifcellanea Curiofa. 79 the North-Eaft Trade-Wind below, will be at- rended with a South-Wefterly above, and the jouth-Fafterly with a North-Weft Wind above ;
at this is more than a bare Conjecture, the al- mott inftantaneous Change of the Wind to the oppofite Point, which is frequently found in paf- fing the limits of the Trade-winds, feems to af- fure us; but that which above all confirms this
Hypothefis is the Phenomenon of the Monfoons, by this means moft eafily folved, and without it hard- Piexpicables A 07 10 : |
Suppofing therefore fuch a Circulation, as a- bove, ’tis to be confidered that to the Northward of the Indian Ocean there is every where Land within the ufual limit of the Latitude of 20, viz. Arabia, Perfiay India, €c. which for the fame reafon as the Mediterranean Parts of Africa, are fubject to unfufferable Heats when the Sun is to the North, pafling nearly Vertical; but yet are temperate enough when the Sun is _ re- moved towards the other Tropick; becaule of a ridge of Mountains at fome diftance within the Land, faid to be frequently in Winter cover'd with Snow, over which the Air, as it pafles, mutt needs be much chill’d. Hence it comes to pafs, that the Air coming according to the ge- -neral Rule, out of the N. E. in the Indian Seas, is fometimes hotter, fometimes colder, than that which by this Circulation is return’d out of the S. W. and by confequence, fometimes the under Current or Wind, is from the N. E. fometimes
from the S. W.
That this has no other Caufe, is clear from the. times wherein thefe Winds fet in, viz. in April,
When the Sun begins to warm thofe Countries “to whe North, the S. W. Monfaon begins, and. blows during the Heats till Ofsber ; when the
Sun
80 | Mifeellanee Curiafa
‘Sun being retir’d, and all things growing cooler” Northward, and ce Heat increafing to the South, the North-Eaft Winds enter and blow all the Winter ill Aprél again. And it is undoubtedly from the fame Principle that to the Southwards of the AZquator, in part of the Indian Ocean, the North-Weft Winds fucceed to the South-daft, when the Sun.draws near the Tropick of Caprix corn; but I muft confefs, that in this latter oc- curs a difficulty, not well to be accounted: for, which is, why this Change of the Monfoons'fhould” be any more in this Ocean, than ip the fame’ La-
titudes in the rhopick, where there is “sohingl more certain than aS. E. Wind-all the Year. ©
Tis likewife very hard to: conceive why the limits of the Trade-wind fhould be fixt, about the thirtieth Degree of Latitude all round) the Globe; and that they fhould fo feldom tranfgrels
or fall hort of thofe-bounds « ; as alfo that in the Indian Sea, only the Northern Part fhould be fubje& to the changeable Monfoons, and in the Southern there be a conftant S. E.
Thefe are Particulars that merit to = ont der’d more at large, and furnifh a fufficient Subs je for a juft Volume, which will bea very com> mendable Task for fuch, who being us‘d to Phi- lofophick Contemplation, fhall have leifure to ap- ai their ferious aes 2 about it,
Ls 3 ae :
Ag A ae: me a
eee
IWHOLE WORLD } Hy) Sherving the Variations off COMPA Ss
as they were found Ano1 00 »
with aView af the General }
hd Wa/jling Trade Win
i) ad Monfoons o7-/hifling Tride Winds
by the Direction of
Western
SS SORE ap = HE NORTH POLE
ee | ee
Mifcellanea Curiofa. 81
e tom a oe Fined : kth
A Difcourfe of the Rule of the De- _ creafe of the height of the Mer- - cury inthe Barometer, accordin
- as Places are elevated above the _ Surface of the Earth ; with an n Attempt to difcover the true Rea- a: fon of | the Rifing and Falling of
_ the Mercury, upon Change of _ Weather. By Edm. Halley.
TPE Elattick Property of the Air his _ A been long fince made out, by Experiments ©
‘before the Royal Society, and elfewhere ; and the Refiftance of its Spring is’ found to be neare ly equal to the Weight. or Force that compref- fes it; as alfo, that the Spaces the fame Air oc- ‘Cupies, under differing Preffures, are reCcipros - ally as thofe Preflures: It has been (hewn like- ‘wile by undoubted Experiment, that the {peci- ‘fick Gravity of the Air, near the Earth’s Sur- Yace to that of Water, was once as 1 to S40 5 again as 1 to 8523 and a thirdtime, in a very large Veflel holding 10 Gallons, as 1 to 860; all which, confidering the Difficulty of the Ex. ‘periment, agree well enough, the Mercury ftand- img at all thofe times about 29 Inches 5: Bur ‘Dy Reafon twas Summer-weather, and conf.
quently,
?
Fs ie ay SES
i % 44
ey of
2s Mw £
* Fe Cee phe ‘jo. > oer eat 7 Bet ttn
4
82 Mifcellanea Curiofa. quently the Air rarified, when all thefe were tried, we may without fenfible Error fay in round numbers, that the Barometer ftanding at — 30 Inches, and in a mean State of Heat and Gold, the fpecifick Gravity of the Air to'Wa- ter, isas1to 800. By the like Trials theweight © of Mercury to Water, is as 123 to 1, or very near it; fo that the ‘weight of Mercury to Air, — is as 10890 to 13; and a Cylinder of Air of 10800 Inches or 900 Feet, is equal toan Inch of Mercury ; and were the Air of an equal den- fity like. Water, the whole Atmofphere would be no more than 5,1 Miles high, and in the Af- cent of every 900 Feet the Barometer would — fink an Inch. But the Expanfion of the Air ine | creafing in the fame proportion as the incumbent weight of the Atmofphere decreafes ; that is, as the Mercury in the Barometer finks; the upper Parts of the Air are much more rarified than the lower, and each Space anfwering to an Inch of Quickfilver, grows greater and greater ; fo that the Atmofphere muft be extended to a much grea- _ ter height. Now, .upon thefe Principles, to de-— termine the height of the Mercury at any affign= ed height in the Air; and ¢ contra, having the height of the Mercury given, to find the height of the Place where the Barometer ftands, are Pro- blems not more difficult than curious; and which I thus refolve. 0 aan are The Expanfions of the Air being reciprocally as the heights of the Mercury, it is evident, that by the help of the Curve of the Hyperbola and its “Afymptotes, the faid Expanfions may be expound- — ed to-any given height of the Mercury: For by the 65th Prop. lib, 2. Conice Mydorgity the Re&an= gles, ABCE, AKGE, ALDE, &c. (in Plate 1. Fig. 4.) arealways equal, and cic : yo
aia
ve ae
os tle!
Mifcellanea Curiofa. 83
dy the fides, CB,.GK, LD, &c. are recipro=
cally as the fides 4 B,.4 K, AL, &c. If then
the Lines 4B, 4K, AL, be fuppofed equal to
the heights of the Mercury, or. the preflures of
_ the Atmofphere, the Lines C B, G K, LD, an-
fwering thereto, will be as the Expaafions of ©
the Air under thofe Preffures, or the Bulks that
the fame quantity of Air will occupy; which Expanfions being taken infinitely many, and
infinitely ‘tittle, ( according to . the Method of
Indivifibles) their Summ will give the. Spaces
of Air between the feveral heights of the Baro- meter; that is to fay, the Summ of all the Lines between C B and KG, or the drea CB KG, will be proportioned to the Diftance or Space intercepted between the Levels of two Places in
the Air, where the Mercury would ftand ar the
heights reprefented by the Lines 4B, 4K; fo |
then the Spaces of Air'anfwering to equal Parts of Mercury in the Barometer, are as the Area’s
CBKG, GKLD, DLFM, &c. Thefe Area’s again are, by the Demontftration of Gregory of _ St. Vincent, proportionate to. the Logarithms
the Numbers exprefling:the Rationes of AK to 4B, of AL to 4K, of 4M to AL, &c. So then by the common “Table of Logarithms,
the height of any Place in the Atmofphere, ha-
ving any aflign’d height of the Mercury, may _mofteafily be found : For the Line C B in the _ Hpyperbola, whereof the Avea’s defign the Tabular Logarithms, being 0,0144.765 ; “twill be, as
ION ales
©, 0144765, to the difference of the Logarithms
of 30, or any other leffer Number, for goo Feet, or the Space anfwering to an Inch of Mer
_ cury, if the Air were equally preft with 30 Inches of Mercury, and every where alike, to the
ier
he Me he ‘
height of the Barometer in the Air, where it 3 G2 will :
84 Mifcellanea Curiofa. will ftand at that leffer number of Inches : * And by the Converfe of this Proportion may the height of the Mercury be found, having the Al- titude of the Place given. From thefe Rules I
deriv’d the following Tables. —
A Table fbewing the|A Table * foewing Altitude, to given| the heights of the heights of the Mer-| Mercury, 4¢ g7- cury. - ven Altitudes.
Inch. -Feer.|Feet. °ssnch, > 20 | .. Stehve Goll 1 eae 290k oon ONG Rooow, tore S28 np 2B. 1862/2000 hh (86 27 2844/2000 - 626 BF 2.6 2863/4000 35 87 25 - 4922|5000 feet 24, 92 $02 i Rogayyt | tamilerdiieeat 67 15 Ag Spi gh) a0 1 ROS 10 2.9 66alrr sig. hi A SS 5- | (48378) 4 13 72
a orig (POTS Fai ¢ rr2s: Oo § 110547]. 10° 4 24 0. 25 129262] 15 1 60
o. & 29mil.or 154000] 20 0.95. 0.01 AT m. or216169| 25 O22 o. oof §3m. 278338) 30 0 08 4.0 o O12
io (er a Oe eee! St Oe a" Gin RSM tS RUBS Re eR
Mifcellanea Cuviofa. 85
J YF PON thefe Suppofitions it appears, that ACB at the height of 41 Miles the Air is (0 ra- vified, as to take up 3000 times the Space it.oc- Cupies here, and at 33 Miles high it would om expanded above 30¢00 times ; but irs probable that the urmoft Power of its Spring cannot exert it felf, to fo great an Exrenfion, and that ‘no part of the Armofphere reaches above 45 Miles from the Surface of the Earth. : This feems confirmd ‘from the Obfrvations of the Crepufeulum, which is obferv’d commor- ly to begin and end when the Sun is about 18 Degrees below the Hcrizon ; for fuppoing the Air to refle& light from its moft rarified _ Parts, and that as long as the Sun iduminates any of its Atoms, they are viGible to’an Eye not intercepted by the Curvity «£ the Earth, it will follow from Fig. §. Plate 1. that the proportion of the height of the whole Air, to the Semi-djame- ter of the Earth, is much about, as 1 to go, or asthe excefs of the Secant of about 82 Degrees — tothe Radius. For if E be the Eye of the Ob- ferver, § a Place where the Sun fers at the end of Twilight in E, and the Arch EC Sur TCs, be found 18 Degrees, the excef of the Scant of _ half thereof EC 4, would be the height of the. peng, vig. GH) But the’ Beam of the Sun AS #H, and the Vifial Ray EH, do each of | them fuffer a Reftadtion of about 32 or 22 Mi- nutes, . whereby being bent inwards from H towards G, the height of the Air need not be ‘fo-great as if they went ftreight 5° and having from -the Angle ECS taken the double Refra. Ction: of the Horizontal Ray, the half of the Remainder will be 82 Degrees circiter, whofe’ Secant being’ to, 111, it follows, that as TOs00 : G 3 oucstae
B6 ~~. Mifcellanea Curiofa. — to rrr, fo the Semi-diamter of the Earth fuppofed 4000 Miles, to 44,4, Miles; which will be the height of the whole Air, if the Places BE, 5, whofe vifible Portions of the Armofphere ERX H, — and S H KB, juft touch one the other, be 18 _ Degrees afunder, JON. Sere ee :
At this height the Air is expanded into a- bove 3000 times the {pace it occupies here, and we have feen the Experience of condenfing it into the Goth part of the fame Space ; fo that it fhould feem, that the Air is Subftance ca-— pable of being comprefled into the 18c0ceth part of the Space it would naturally take up, when free from preffure. Now what Texture or Compofition of Parts fhall be capable of this © great Expanfionand Contraction, feemsa veryhard Queftion ; and which, I fuppofe, is {carce fuffici- ently accounted for, by comparing it to Wool, Cotten, and the liké {pringy Bodies. | . Hitherto 1 have only confider’d the Air and ‘Atmofphere, as one unalter’d Body, as having conftantly at the Earth’s Surface the Sooth ~~ -part of the weight of Water, and. being capa- ble of Rarifaction. and Condenfation in infini- tum ; neither of which Hypothefes are rigidly true: _ For here in England it is notorioufly known, that the weight of the whole Armofphere is va~ rious, being counterpoifed fometimes by 282 Inches of Mercury, and at other times by no ~ lefs than 303; fo that the under. parts being ” preffed by about a 15th part, lefs weight, the fpecifick, Gravity of the Air upon that fcore will fometimes be a 1§th.part lighter than another ; befides Heat and Cold, does very confiderably — dilate and contract the Air, and conféquently alter its Gravity ; to which add the mixture of Effluvia, or {teams arifing from almoft all Bo-
dies,
— Mifiellanea Curiofa. 87
dies, which affimulating into the Form of Air, are kept fufpended therein, as Salts diffolv’d in Liquorsy or {Metals. in corroding Menjfrua; , which Bodies being all of them very much hea- vier than Air, their- Particles by their Admix- ture muft needs encreafe the weight of that Air they lie incorporated withal, after the fame man- ner as melted Salts do augment the fpecifick Gravity of Water. The other Confideration is, that the Rarifaction and Condenfation of the Air is not precifely according to the pro- _ portion here laid down ; for the Experiment ve- , ‘ry nearly agrees thereto, as may be feen in the 58th Chapter of Mr. Hook’s Micrography 5 yet are the Condenfations not poffible beyond cer- tain degrees: For being comprefled into an, Sooth part of the. Space it takes up here, its confiftence would be equally denfe with that of. Water ; which yields not to any force whatfos ever, as hath been found by feveral Experiments tried here, and at Florence,*by the Academia del Cimento. Nor can the Rarifaction. proceed én infinitum; for fuppofing the Spring where-_ by. it dilates ic felf; occafion’d by what Tex- ture of Parts you pleafe, yet muft. there be a determinate Magnitude of the natural State of each Particle, as we fee it is in Wool, and the like, whofe Bodies being compreffable into a very - fmall Space, have yet a determinate bulk which they cannot exceed; when free’d from al! manner
es OTe a et ee " a ia Thefe. Objections being true, do difturb the - Geometrical Accuracy of thefe Conclufions, drawn from the {pecifick Graviry of the° Air obferv’d at any time 3, but the Method here fhewn will compute by. a like Calculation, the
heights of ‘the Quick-hlver, and the Rarifactions
4 : i
88 Mifcellanea Curiofa. of the Air from any affign’d height of the Ba- vometer at the Earth’s Surface, and any fpecifick Gravity given. As to the Condenfation and _ RarifaCtion by Heat and Cold, and the various _ mixture of Aqueous and other Vapours, thefe two Objections feem generally to compenfate | -each other ; for when the Air is rarihied by Heat, they are raifed moft copioufly ; fo that though the Air properly fo call’d, be expanded, and con- fequently lighter, yet the Interftices thereof being crouded full of Vapours of much heavier Mat- ‘ters, bulk for bulk, the weight of the Compofi- zum may continue much the fame; at leaft a — -moft curious Experiment made by the Ingenious Mr. Fohn Cafwell, of Oxfords upon the top of Snowdon Hill, in Carnarvanfhire, feems to prove, that the firft Inches of Mercury have their Por- tions of Air near enough to what I now deters mine: For the height of the Hill‘being 1240 Yards, or very near it, he found the Mercury — to have fubfided to 25,6 Inches, or 4. Inches be-. low the mean Altitude thereof at the Level of © the Sea, (which is a greater difference than has been found in any of our former Experiments,) and the Space anfwering to 4 Inches, by my Calculation, fhould be 1288 Yards; and it a- grees as we'll with the Obfervations im the Ap- pendix to Mr.'Pafcall’s Book, del Equilibre des Liqueurs, made on the high Hill in Auvergne, calld te puy de Domme. & that the Rarifacti- on and Vapours feem not to have alter’d con- fiderably, the Gravity of the under’ Parts of the Air ; and much above the height where thefe Experiments were made, da few Vapours ‘af; cend,’ and the “Cold is fuch that the Snow lies continually, fo that for the moreelevated Parts of — the Sphere of ir, there is much lef Reafon to doubt. ree But
~
MifcellaneaCuriofa. - 89 _ But now we have had occafion to mention the difference there is between the height of the Mercury at one time, from the height thereof at another, it may not be unacceptable to offer. at fome Reafons for the faid difference ; which, at leaft to my felf, feem to have fome appearance of Truth: Firft, Then it’s undoubtedly demon- _ ftrable, that the height of the Cylinder of Mer- cury is equal to the weight of the whole incum- bent Air, and confequently that that whole is fometimes a fifreenth more than at other times ; which cannot otherwife be, but by the ‘accefs of new Matter when ’tis heavy, and its diminution when tis light ; that Hypothefis therefore that fhews how the Air fhall be encreafed or diminifhed, in any particular place, will give a Reafon for the greater and leffer height of the Mercury in the Barofcope: But to dire& us in the choice of the feveral Caufes, which may be affign’d for the Increafe and Decteafe of the Air, ’twill not be un- neceffary to enumerate fome of the principal Ob- - fervations made upon the Barometer, moft where- of are fufhciently known already to all thofe that are curious in thefe Matters. :
* The Fixftis, That in calm Weather, when the . ey e . 9 ° eo d 3 Air is inclin'd to Rain, the Mercury is common-
"That in ferene good fettled Weather, the
LPPEDS. oust RB
. a
Compals the Wind blows upon. |”
4. That
go Mifcellanea Curiafa,
4. That cogil paribus the greateft heights of the Mereury are found upon Eafterly and North- Kafterly Winds. A deehanerbi nah
4g. That in. calm frofty Weather: the. Mercury generally ftands high. ig ¢
6. That after very great Storms of Wind, ein the Quickfilver has been low, it generally rifes again very faft. 2, hae ania
7. That the more Northerly places have greas. ter Alterations of the Barofcope, than the more Southerly. ; i
8. That within the Tropicks and! near thems, thofe Accounts I have had from others, and my own Obfervation at St. Helena, make very little. or no Variation of the height. of the Mercury in all Weathers, Now that Theory that can well ac- count for all thefe appearances, will, in all pro- bability, approach nearer the true caufe of the Barometers Variations, than any thing hitherto afforded ; and fuch an one I am bound to be- - lieve, is thac which I here lay down with fub-
miffion to better Judgments. I conceive that the principal Caufe of the rife and fall of the Mercuryy: is from the variable Winds, which are found in the Temperate Zones, and whofe great unconftancy here in England is moft notorious, I fhall not at prefent inquire into the Caufe of its uncertainty, but the Matter of Fact being moft undoubted, the Legitimate Confe- quences:thereof_ muft be allow’d .mey lek it pro- ceed from what it-will, -- ©) 0) a) 2 2D
A
Mifcellanea Curiofa. . 91
A fecond Caufé is the uncertain Exhalation and Precipitation of the Vapouts lodging in the Air, whereby it conres to be at one time much more crowded than at another, and confequently hea- ‘vier 5 but this latter in a great meafure depends upon the former. Now from thefe Principles I - fhall endeavour to explicate the feveral Phenomena of the Barometer, taking them in the fame order
I laid them down. — |
1. Whyin calm Weather the Air being inclined to Rain, the Mercury is commonly low >? -1 Ane fwer, That the Mercury’s being low, inclines it to Rain ; for the Air being light, the Vapours are no longer fupported thereby, being become fpecifically heavier than the Medium wherein they floated; fo that they defcend towards the Earth, and in their fall meeting with other -aqueous Particles, they incorporate together, and form little drops of Rain; but the Mer- _eury’s being at one time lower than another, is the effect of two contrary Winds blowing from _ the place whence the Barometer ftands; wheree _by the Air of that place is carried both ways from it, and confequently the incumbent Cylin- der of Air is diminifhed, and accordingly the Mercury finks ; as for Inftance, if in the Ger» man Ocean it fhould blow a Gale of Wefterly Wind, and at the fame time an Eafterly Wind in the Ivifh Sea; or if in France it fhould blow a Southerly Wind, and in Scotland a ‘Northern ; it muft be granted me, that That’ part of the Atmoefphere impendent over England, would there- by be exhaufted and attenuated, and the Mer. cury would fibfide, and the Vapours which be. fore floated»in thofe parts of the dir of equal Gra- vity ‘with themfelves, would fink to the Earth, -
‘ ; 2. Why
92 Mifcellanea Curiofa.
2. Why in ferene geod fettled weather the Mer- cury is generally high? To this I Aniwer, That the greater height of the Barometer, is occafion’d by two contrary Winds blowing towards the place of Obfervation, whereby the Air of other
places is brought thither and accumulated ; fo
that the incumbent Cylinder of Air being en- creas both in height and weight, the Mercury prefs'd thereby muft needs rife and ftand high, as long as the Winds continue fo to blow; and then the Air being fpecifically heavier, the Vapours are better kept fufpended, fo that they have no inclination te Preecipitate and fall down in Drops, which is the reafon of the ferene good Weather, which attends the greater heights of the Mer- cury. | to
2. Wiy upon very great Winds or Storms, tho? accompanied with no Rain, the Mercury finks lowe eft of all, with relation to the Point of the*Compafs upon which the Wind. blows? This is causd by the very rapid Motion of the Air in thefe Storms ; for the Traét or Region of .the Earths Surface,
wherein thefe Winds rage, not extending all
round the Globe, that ftagnant Air which is left behind, as likewife that on the fides,’ can- not come in fo faft as to fupply the Evacuation made by fo {wift a Current ; fo that the Air
muft neceflarily be attenuated, when and where
the faid Winds continue to blow, and that more or lefs, according to their Violence ; add. to which, that the Horizontal Motion of the
Air being fo quick as it is, may in all probabi- | lity take off fome part of the perpendicular —
preffure thereof: and the great’ Agitation «of — its, Particles, is the Reafon. why the -Vapours: are diffipated, and do not condenfe:into Drops,’
‘ fo
Mifcellanea Gihtifa. 93 |
fo as to form Rain, otherwife. the natural Confe- aes of the Airs Rarifaction.
4. Why ceteris paribus Ne Mercury lands higheft upon an Eafterly or North- Bajterly Wind 3 _ This happens becaufe thar in the great Atlantich Ocean, on this fide the thirty fifth Degree of North Latitude, the Wefterly and South-Welterly ‘Trade- Winds blow almoft always ; fo that when- ever here the Wind comes up at Eaft and North- Eaft, *tis fure to be checked by a contrary Gale, as foon as it reaches the Ocean ; wherefore, ac- cording to what is made out in our fecond Re-
mark, the Air muft needs be heaped over this Wand ; ; and confequently the Mercury mutt ftand high, as often as thefe Winds blow. ‘This holds true in this Country, but is not a gene- ral Rule for others, where the Winds are under different Circumftances ; and | have fometimes feen the Mercury here as low as twenty nine Inches, upon an Eaiterly Wind, but then it blows exceeding hard, and fo comes to be ac- counted for by what was obferv'd upon the third Remark.
“5. Why in calm Weather the Mercury gene- nerally ftands high 2 The caufe hereof i is, as I conceive, that it feldom freezes bute when the Winds come out of the Northern and North- ~ Eaftern Quarters, orat leaft unlefs chofe Winds blow at no great diftance off; for the Nor- thern Parts of Germany, Dibibene Sweden, Nor- way, and all that Tract from whence North- Eaftern Winds come, are fubjeét to almoft con- tinual Froft all the Winter; and thereby the Tower Air is very much condens’d, and in chat. ‘State. is brought Giga! by thele Winds,
and
94. Mifiellanea Curiofa.
and being accumulated by the oppofition of che Wefterly Wind blowing in the Ocean, the Mer- cury muft needs be preft to a more than ordina- ry height, and as a concurring Caufe, the fhrink- ing of the lower parts of the Air into leffer room by cold, muft needs caufe a defcentof the upper parts of the Atmofphere, to reduce the
Cavity made by this contra¢tion’ to an 4guili-
brium.
6. Why after very great Storms ; Wind, when -
the Mercury has been very low, it generally rifes again very faft 2 This I have frequently obfer-
ved, and once found it rifen an Inch and a half in lefs than fix Hours, after a long continu’d
Storm of South-Weft Wind. ‘This feems to be - occafion’d by the fudden Acceflion of new Air to
fupply the great Evacuation which fuch con-
tinu’d Storms make thereof, in thofé places whence they happen (asin the third Remark) and by the Recoile of the Air, after the force ceafes that impell’d ic; and the Reafon why the Mercu- zy tiles fo faft, is becaufe the Air being very much rarify’d beyond itsmean denfity, the Neighbouring Air runs in the more fwiftly to bring it to an fEquilibration, as we fee Water runs the fafter
for having a great declivity.
7: Why in more Northerly. places the Variations of the Barofcope are greater than in the Southerly 2 The truth of the. Matter of Fact. is prov’d from Obfervations made at Clermont and Pars, compar d with others, made at Stockbolm, as may be feen in
the Appendix to Mr. Pajfcal’s Book before-cited. —
« The Reafon I conjecture to be, that the more Nor- therly Parts have ufually greater Stormsof Wind
than the more Southerly, whereby the Mercury fhould
as 8
Mifcellanea Curiofa. 95 fhould fink lower in that Extream; and then the Northerly Winds bringing the condens’d and ponderous Air from the Neighbourhood of the Pole, and that again being check’d by a Southerly Wind, at no great diftance, and fo heaped, mutt of neceflity make the Mercury in fuch cafe ftand higher in the other Extream. .
-. 8 And Laftly, Why near the. AaquinoGial, as at Barbadoes and St. Helena, there is very little
or no Variation of the height of the Barometer 3?_
‘This Remark, above all others, confirms the Hypothefis of the variable Winds, being the caufe of thefe Variations of the height of the Mercury ; for in the Places above-named, there is always an eafie Gale of Wind blowing nearly upon the fame Point, viz. E. N.E at Barbadoes, and E. S. E. at St. Helena ; fo that there being no contrary Cur- rents of the Air, to exhauft or accumulate ir, the Atmofphere continues much in the fame State : However, upon Hurricanes, the moft violent of _ Storms, the ‘Mercury has been obferv'd very low, but this is but for once in two or three Years, and it foon recovers its fettled ftate of abont 29} Inches. I doubt not but the fame thing is in the Eaft Coaft of Africa, and in. India, where the Monfoons or Trade-Winds»are for half the Year one way, and half the Year another; only it’s probable, that there may fomething worth noting happen, about the times of the change cr fhifting of the Winds, which might be obtain’d, if any ~ Body had the Curiofity to keep the Barometer at our Factories in India.
I doubt not but this Doétrine will find fome Oppofers, and that one principal Objection will be, that I fuppofe the Air fometimes to move from thofe Parts where it is already eva
| elow
cay, << .
96 Mifcellanea Curiofa.
below the £quilibrium, and fometimes again tos wardsthofe parts, where it is condensd and croud- ed above the mean State, which may be thought contradictory to the Laws of Staticks and the Rules of the quilibrium of Fluids. But. thofe that fhall confider how, when once an impetus is given to a Fluid Body, it is capable of mount- _ ing above its Level, and checking others that have a contrary tendency to defcent by their own Gra- vity, will no longer regard this as a material Ob- ftacle, but will rather conclude, that. the great Analogy there is between the rifing and falling of the Water upon the Flux and Reflux of the Sea, and this of the accumulating and extenuating the Air, isa great Argument for the Truth of this Hypothefis: For as the Sea over againft the Coaft of Efex, rifes and {wells by the meeting ofthe two — contrary Tides of Flood, (whereof the one comes from the S.W. along the Channel of England, and the other from the North) ; and on the con- trary finks below its Level upon the retreat of the — Water both ways in the Tide of Ebb; fo ‘it is very probable that the Air may Ebb and Flow, ‘after the fame manner 3 but by reafon of the di- verfity of Caufes, whereby the Air may be fet in moving, the times of thefe’ Fluxes and Refluxes thereof, are purely Cafual, and not reducible to any Rule, as are the Motions of the Sea, depend- ing wholly upon the regular Courfe of the Moon.
Plate 1. pag97
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a SR eye har 4
: =
Mifcellanea Curiofa. ! 97
A Letter of Mr. Ifaac Newton, _ Profeffor of the Mathematicks in the Univerfity of Cambridge ; containing bis New Theory about Light and Colours: Sent by
: the Author to the Publifher from
- Cambridge, Feb. 6. 167: 5 in - order te be communicated to the Royal Society. | STR, | a oP perform my late promife to you, I fhall
without further Ceremony acquaint you,
_ That in the beginning of the Year 1666 (at _ which time I apply’d my ‘elf to the grinding of
Optick-glaffes of other Figures than Spherical,) I procur’d me a Triangular Glafs-Prifm, to try therewith the telebrated Phenomena of Colours.
And in order thereto, having darken’d my
Chamber, and made a fmall hole in my Win-
dow-fhuts, to let ina convenient quantity of the Sun’s Light, I plac’d my Prifm at his entrance, that ic might be thereby refracted to the oppo-
fice Wall. It was at firft a very pleafing Diver-
4 tifement, to view the vivid and intenfe Colours | produced thereby ; but after a while applying my _ felf to confider them more circumfpeCtly, 1 be-
came furpriz’d to fee them in an oblong Form ;
_which, according to the received Laws of Rare-
fra&tion, 1 expected fhould have been Circular. ae | They
Ae
98 ifcellanea Curiofa.® -. They.were terminated at the fides with ftreight Lines, but at the ends, the decay of Light was fo gradual, thatit was difficult to determine juft- ly, what was their Figure ; yet they feem’d Se- pireirbal are SIDI SOT Mg TOUS Tey Comparing the: length of this colour’d Spe- étrum with its breadth, 1 found it about five times greater ; a difproportion fo extravagant, that it excited me to a more than ordinary Cariofity of examining, from whence it might proceed. I
AD in oN ee qe
could fcarce think, that the various thickneS of —
the Glafs, or the termination with fhadow or darkneis, could have any Influence on Light to produce fuch an effeét’; yet I thoughr it not amifs, firft to examine thofe Circumftances; and
fo try’d what would happen by tranfmitting ~ Light through parts of the Glafs of divers thick- _ nefles, or through. holes in the Window of divers
bignefles, or by fetting the Prifm without, fo that the Light might pafsthrough it, and be refra&t- ed before it was terminated by the hole: But I found none of thofe Circumftances material. ‘The
fafhion of the Colours was, in all thefe Cafes,
the fame.
Then 1 fufpected, whether by any uneven- *
-nefsin the .Glafs, or. other, contingent’ Irregu- larity, thefe Colours might be thus dilated. And
te try this, I took another Prifm like the former, —
and fo.plac’d it, that the Light paffing through |
them both, might be refraéted contrary ways, — and fo by the latter return’d into that Courfe, —
.from which the former had diverted ‘it. For, — -by this; means, I thought the regular effects of |
the firft. Prifm would be deftroy’d by the fecond
Prifm, but the irregular ones more augmented — by the multiplicity of RefraGtions, The Event —
was, that the Light, which by the firft Prifm
Was
+
Mifcellanea Curiofa. 99 was diffufed into an oblong Form, was, by the fecond, reducd into an orbicular one, with as much regularity, as when it did not at all pafs through them. So that whatever was the caufe of that length, *twas not any contingent Irregularity:
_ I then proceeded to examine more critically,
what might be effected by the difference of the incidence of Rays coming from divers parts of the Sun; and to that end, meafur’d the feveral
Lines and Angles belonging to the Image. Its diftance fromthe Hole or Prifm was twenty two Foot ; its utmoft length 132 Inches; its breadth 2%; the Diameter of the Hole 4 of an Inch 5; ‘the Angle, with the Rays, tending towards the
middle of the Image, made with thofe Lines, in
which they. weuld have proceeded without Refra- , Mion, was 44°56!.. And the Vertical Angle of the Prifm, 63°12'. Alfo the Refraétions on beth fides the Prifm, that is, of the Incident, and
Fimergent Rays, were as near, as 1 could make them, equal, and confequently about 54° 4’. _ And the Rays fell perpendicularly upon the Wall.
Now fubdu@ing the Diameter of the Hole from ' the length and breadth of the Image, there re- mains 12 Inches the length, and 23 the breadth,
comprehended by thofe Rays, which pafled thro’
the Center of the “aid Hole, and confequently
the Angle of the Hole, which that breadth fub--
tended, was about 21!, anfwerable to the Sun’s Diameter ; but the Angle, which its length. fub- tended, was more than five fuch Diameters, name-
ly 2° 4o!. : Having made thefe Obfervations, | firft com- puted from them the refra@tive Power of that _ Glafs, and found it meafur’d by the ratio of the Sines, twenty to thirty one. And then, by that ratio, I computed the Refraftions of two Rays } i 2 flowing
100 «© Mifcellanea Curiofa. flowing from oppofite parts of the Sun’s difcus, - fo as to differ 21! in their obliquity of Incidence, aad found that the emergent Rays fhould have comprehended an Angle of about 31!, as they did, before they were incident. oe But becaufe this Computation was founded on the Hypochefis of the propottionality of the Sines of Incidence and Refra&tion, which, tho’ by my own Experience I could not imagine to be fo er- roneous as to make that Angle but 21’, which in reality was 2° 49; yet my Curiofity caus’d me again to take my Prifm. And having plac’d it at my Window, as before, I obferv’d, that by turning it a little about its Axis to and fro, fo as to vary its obliquity to the light, more than an Angle of four or five Degrees, the Colours were _ not thereby fenfibly tranflated from their place — on the Wall, and confequently by that Variati- on of Incidence, the quantity of Refraction was not fenfibly varied. By this Experiment there- fore, as well as by the former Computation, it was evident, that the difference of the Incidence of Rays, flowing from divers parts of the Sun could not make them, after decuffation, diverge ata fenfiblygreater Angle,than that at which they before converged ; which being, at moft, but about thirty one or thirty two Minutes, there {till remain’d fome other caufe to be found our, from whence it could be two Deg. 49 Min.. Then I began to fufpeét, whether the Rays, after their ‘T'rajection through the Prifm, did not move in curve Lines, and according to their more or lef; Curvity, tend te divers parts of the Wall. And it increas’d my fufpicion, when I remember’d that I had often feen a Tennis-Ball, — flruck with an oblique Racket, defcribe fuch a curve Line. For a Circularas well asa Pro-
greflive
ole Vg SS ea Sd aii MR At aul US Meee ae le mi RN a 5H aware rs ieee ; ; P
_ Mifcellanea Curiofa. 101 greflive Motion being communicated to it by that ftroak, its parts-on that fide, where the Mo- tions confpire, muft prefs and beat the contigu- ous Air more violently than on the other, and there excitea Reluctancy and Reaction cf the Air proportionably greater. And for the fame Rea- fon, if the Rays of Light fhould poflibly be glo- bular Bodies, and by their oblique Paflage out of one Medium into another, acquire a circulating Motion, they ought to feel the greater refiftance from the ambient Asther, on that fide, where this Motion confpires, and thence be continually ‘bowed to the other. But notwihftanding this plaufible ground of fufpicion, when I came to examine it, | could obferve no fuch Curvity in them. And befides (which was enough for my
~ purpofe) I obferv’d, that the difference ’twixt the length of the Image, and Diameter cf the Hole, through which the Light was tranfmitted, was
_ proportionable to their diftance. The gradual removal of thefe fufpicions, at length led me to the E xperimentum Crucis, which was this; I took two Boards, and plac’d one of them clofe behind the Prifm at the Win- dow, fo that the light might pafs through a {mall hole, made in it for the purpofe, and fall on the other Board, which I plac’d at about _twelve.Feet diftance, having firft made a {mall hole in it alfo, for fome of that incident Light to pafs through. ‘Then I plac’d another Priff be- _ hind this fecond Board, fo that the Ligit, tra-, jeGted threugh both the Boards, might pafs thro that alfo, and be again refracted before it ar- rived at the Wall. ‘This done, I took the firft Prifm in my Hand, and turn’d it to ard fro flowly about its Axis, fo much as to make rhe feveral parts of the Image, caft on the fecond Board,
Eg i 3 — fucceifively
a
au’ Be eee. Se eee Pe, oe eee WE eA art we ee, « Pa EN Se ee eh ne é +) Soe , ep Laas
102 Mifcellanea Curiofa. ~ fucceflively pafs through the hole in it, that I might obferve to what places on the Wall the fecond Prifm would refra&t them. And | faw by the Variation of thofé places, that the Light, tending to that end of the Image, towards which the Refraction of the firft, Prifm was made, did, in the fecond Prifm, fuffer a RefraGtion confider- ably greater than the Light tending to the other end. And fo the true caufe of the length of | that Image was detected to be no other, than that Light confifts of Rays differently refrangible, which, without any refpect to a difference in their. inci- dence, were, according to their degrees of Refrari- gibility, tranfmitted towards divers parts of the W all. | che glia: When I underftood this, I left off my aforefaid Glafs Works; for I faw, that the perfection ‘of Telefcopes was hitherto limited, not fo much for want of Glafles truly figur’d, according to the - prefcriptions of Optick Authors (which all Men have hitherto imagin’d), as becaufe that Light it
~ iF isa Heterogencous mixture of differently refran-
gible Rays. So that, were a Glafs fo exadtly fi- gur'd, fo as to colle& any one fort of Rays into — one Point, it could not colleét thofe alfo into the fame Point, which having the fame Incidence upon the fame Medium, are apt to fuffer a diffe. rent Refraction. Nay, 1 wonder’d; that feeing the difference of Refrangibility ‘was fo great, as 1 found it, Telefcopes fhould arrive to: that per= fe€tion they are now at. For,’ meafuring the RefraGtions in one of my Prifms, I’ found, that, fuppofing the common Sine of Incidence upon one of its plains, was forty four-Parts, the Sine of Refraction of the utmoft Rays on the red“end of the Colours, made out of the “Glaf ‘into the — Air, would be fixty eight parts, and’the: Sine of — as | 7 C Ft. Reiittion
4
a
_ - Mifcellanea Curiofa. 103 Refraction of the utmoft Rays oa the other end» fixty nine parts ; fo that the difference is about a
a
twenty fourth or twenty fifth part of the whole’ Refraction. And confequently. the Object glafs
of any Telefcope cannot colic&, all the Rays, which come from one point of an Object, fo as to make them convene at its Focus in lefs room than; in a, Circular fpace, whofe Diameter is the fiftieth part of, the Diameter of its. Aperture ; which is an irregularity, fome hundred of times greater, than a circularly figurd Lens, of fo {mall a fetion as the Objet-glafles of long T'elefcopes
. are, would caufe by the unfirnefs of its Figure, were Light uniform. . . .| Fhis made me take Reflef&ions into.Confidera- tion, and finding- them regular,’ fo that the * Angle of Reflection of all forts of Rays was
equal to their Angle of Iicidence ; I underftood,
thac by .their mediation, Optick Inftruments |
might be brought to any degree of PerfeCtion imaginable, , provided a Reflefting Subftance could be found, which would polifh as finely as Glufs, and. refle&.as,much Light as Glafs tranfmits, and the, art of communicating to it a Parabolick Fi- gurebe alfo attain’d.. Bur there fegm’d very great Difficultities, and.I have almoft thought them in- Auperable, ,»when I further confider’d, that every drregularity in a. refleting Superficies makes the Rays ftray, five or fix times mere out of their due courfe, than the like Irregularities in a refracting tone; So. that a much greater Curiofiry would be here requifite, thanyin Figuring Glafles for Re-
RES RR aa ai sa ee amidft thefe, Thoughts I was furc’d from Cam- abyidge, by the Intervenjng Plague, and ir was -Bimers, than tion, Mears priors L proceeged further. aus thsn baying spought go a tender way of, pe- Pa ee ee iene,
Larsoix>
104 Mifcellanea Curiofa. lifhing, proper for Metal, whereby, as 1 ima: gind, the Figure alfo would be correéted to the laft ; Tbegan to try what might be effected in this hind, and by degrees fo far perfected : an In- - rrdeene (in the effential parts of it like that I fent to. London) by which] could difcern Jupiter's four Concomitants, and fhew’d them divers times to two others of my Acquaintance. [ could alfo difcern the Moon-like Phafe of Venus, but not very diftin@ly, nor without fome nicenefs in di- fpofing the Inftrument. |
From that time I was interrupted, till thi hat Autumn, when I made the cther. And as that was fenfibly better than the firft (efpecially for Day-Objects,) fo I doubt not but they will be ftill brought to a much greater perfection by their’ _ Endeavours, who, as you inform me, are tebe
care about it at London = &
I have fometimes thought to make a Mierofeapes which in like manner fhould have, inftead of an ObjeCt-glats, a refle@ing piece of Metal. » And this | hope they will alfo take into Confideration : For thofe Inftrumentsfeem as capable of i improve- ment as Telefcopes, and perhaps more, becaule but one refleétive piece of Metal is requifite’ in them, as you may perceive in Plate 3. Fig. 1: where 4 B reprefenteth the Obje&t Me il, C D- the Eye-glafs, F their common Focus, and O the other Focus of the Metal, in which the. Ob- ject is placeds 5 ~ But to return , this digréllegs? 7 told you, that Light is not fimilar, or homogeneal,
but confifts of difform Rays, fome of which are more refrangible than others: So that of thofe, which are alike incident on the fame Medium, fome fhall be more refra&ted than’ others, and thar not by any virtue of the Glafs, ‘or other externa}
MijfcellaneaCuriofa. 105 external Caufe, but from a predifpofition, which every particular Ray hath to fuffer a particular degree of Refraction. ‘ . I fhall now proceed to acquaint you with anc- ther more notable deformity in its Rays, wherein the Origin of Colours is unfolded : Concerning which I fhall lay down the Do&rine firft, and then, for its Examination, give you an Inftance or two of the Experiments, asa Specimen ofthe reft. The Do&rine you will find comprehended and illuftrated in the following Propofitions. ; 1. As the Rays of Light differ in degrees of Refrangibility, fo they alfo differ in their dif- pofition to exhibit this or that particular Co- lour. Colours are not Qualifications of Light, derived from Refractions, ‘or Reflections of na- tural Bodies, (as ’tis generally believed) but Or7- ginal and connate Properties, which in divers Rays are divers. Some Rays are difpofed to exhibit a red Colour and no other ; fomea yellow and no other, fome a green and no other, and fo of the -reft.' Nor are there only Rays proper and par- ticular to the more eminent Colours, but even to all their intermediate Gradations, yo 2. Lo the fame degree of Refrangibility ever ‘belongs the fame Colour, and to the fame Co- -lour ever belongs the fame degree of Refrangi- bility. The deaf? Refrangible Raysare all difpo- fed to':exhibit a Red Colour, and contrarily thofe Rays, which are difpofed to exhibit a Red ‘Colour, are all the: leaft Refrangible : -So the moft Refrangible Rays are all difpofed to exhibit _adeep Violet Colour, and contrarily thofe which ‘are apt to exhibic fuch a’ Violet Colour, are all the moft. Refrangible... And foto all the inter- -mediate Colours:'in a continued Series belong “intermediate degreés of -Refrangibility. And ya! | , | ie:
106 = Mifcellanea Curiofa. | this Analogy ’twixt Colours, and Refrangibility, is very precife and {tri&; the Rays always either exactly agreeing in both, or: proportionally. dif- agreeing in’ both. 1 basaenp Meese bed
» 3. ‘The Species of Colour,: and Degree of Re- frangibility proper to any particular fort of Rays, is not mutable by Refraction, nor by Refleétion from Natural Bodies, nor by any other Caufe,
that I could’ yet obferve.. When any one fort
of Rays hath been well parted from thofe of o- ther kinds, it hath afterwards obftinately: retain’d
a
its Colour, notwith{tanding my utmoft Endea-- _ vours to change it. [I have refraGted it swith — Prifms, and reHe&ted it with Bodies, which in
Day-light were of other Colours ; Ihave inter. cepted it with the colour’d Film. of: Air interce- ding two comprefled Plates of Glafs ; tranfmitted it through colour’d Mediums, ‘and ‘through \Me-
diums irradiated with other forts of Rays, and —
diverfly terminated it, and yet could «never pro- duce any new Colour out of it. It would by
contracting and dilating become more brisk, or —
faint, and by: the lofs of «many: Rays in fome _ Cafes very obfcure and dark ;: but: I could never fee it chang’d im fpecte.:vi00> omaha
© 4. Yet feeming Tranfmutations of Colours —
may be made,’ where there is any mixture of di- vers forts of Rays.': For. in fuch mixtures, ‘the
‘component ‘Colours appear ‘not, but bytheir mu- —
‘tual: allaying each cother;:coiftitute a midling
Colour. And therefore; :! if by Refraction; or —
any othertof the. aforefaid. Caufes, :the difform ‘Rays, latent in fuch a mixture, »be feparated, ithere: fhall emerge‘ Colours ‘differeno*from »the
-colour of the Gompofition.:'“‘Which*Coloursare ©
“hot new generated,:-but: onlysmade apparent ‘by. being ‘parted ';°for' if they.sbe again intirely
mix’d >
Mifcellanea Curiofa. 107 mixd and blended together, they will again compofe that Colour, which they did before fe- ration. And for the fame reafon, Tranfmu- tations made by the conveniag of divers Colours are not real; for when the diflorm Rays are again fevered, they will exhibit the very fame Colours, which they did before they entered the Compofition; as you fee, Blue and Yellow Pow- ders, when finely mixed, appear to the naked Eye Green, and yet the Colours of the compo- nent Corpufcles are not thereby really tranfmu- ted, but only blended. For, when viewed with a good Microfcope, they {till appear Blue and Yellow inter{perfedly. | 5. There are therefore two forts of Colours. The one Original and Simple, the other com- pounded of thefe. The Original or Primary Colours are, Red, Yellow, Green, Blue, and a Violet-purple, together with Orange, Indico, and an indefinite variety of intermediate Gradations. 6. The fame Colours in Specie with thefe pri- mary Ones, may be alfo produced by Compofi- tion: For, a’mixture of Yellow and Blue makes Green; of Red and Yellow, makes Oxange; o! Orange and Yellowiffo Green, makes Yellow, And in general, if any two Colours be mix’d, which ity the Series of thofe, generated by the Prifm, are not too: far diftant one from another, they. by ’ their mutual Alloy compound that Colour, which in the faid Series appeareth in the mid-way be- tween ‘them. »But thofe, which are fituated at too great a diftance, do not'fo.. Orange and In- dico produce not the intermediate Green, nor Scay- Jet and Green the intermediate Yeliow. gs But the moft furprizing and wonderful Compofition was ‘that of Whirene/s, There: is - no-one fort of Rays which alone can exhibit this. ae ae eae
{
108 =Mifcellanea Curiofa. "Tis ever compounded, and to its Compofition are requifite all the aforefaid primary Colours, mix’d in adue proportion. I have often with admiration beheld, that all the Colours of the | Prifm being made to converge, and thereby to be again mixed as they were in the light before it was incident upon the Prifm, reproduced light, intirely and perfectly white, and not at all fenfi- bly differing from a direé light of the Sun, une lefs when the Glaffes, I ufed, were not fufficient- - ly clear; for then they would a little incline it. to their Colour. sare | |
8. Hence therefore it comes to pafs, that Whitenefs is the ufual Colour of Light; for Light is a confufed aggregate of Rays, indued with all forts of Colours, asthey are promifcuoufly darted from the various parts of luminous Bodies. And — of fuch a confufed aggregate, as I faid, is genera- ted Whitenets, if there be a due proportion of the Ingredients; but if any one predominate, the Light muft incline to that Colour ; as it happens in the blue Flame of Brimftone, the yellow; Flame of a Candle, and the variours Colaurs of. the fixed Stars. ky Die
g. Thefe things confider’d, the manner, how Colours are produced by the Prifm, is evident. For, of the Rays, conttituting the incident Light, fince thofe which differ in Colour pro- portionally differ in Refrangibility, they by their unequal RefraCtions mult be fevered and difper-- fed into an oblong Form, in an orderly fuccef- fon, from the leaft refraéted Scarlet to the moft refracted Violet. And for the fame reafon it is, that Objects, when look’d upon through a Prifm, appear coloured. For the difform Rays, by their unequal Refractions, are made to diverge towards feveral parts of the Retiza, and there -
prefs
etree Pr OP bs eeepa ee} “ee. \ iy Pe rd < taal es ake
Mifcellanea Curiofa. 109 prefg the Images of things coloured, as in the for- mer cafe they did the Sun’s Image upon a Wall. And*by this inequality of Refractions, they be- come not only coloured, but alfo very confufed and indiftinct. |
10. Why the Colours of the Rainbow appear in falling drops of Rain, is alfo from hence evi- dent. For thofe drops, which refraé the Rays, difpofed to appear Purple, in greateft quantity _ to the Spedtators Eye, refrat the Rays of othes forts fo much lefs, as to make them pafS befide . it 3 and fuch are the drops on the infide of the Primary Bow, and.on the outfide of the Secon- _ dary or Exteriour one. So thofe drops, which re- fra& in greateft plenty the Rays, apt to appear red, toward the Spectator’s Eye, refract thofe of other forts fo much more, as to make them pafs befide it ; and fuch are the drops on the Exteri- our part of the Primary, and- Interiour part of the Secondary Bow. |
11. The odd Phenomena of an infufion of ~Lignum Nephriticum, Leaf-gold, Fragments of co- ~ lour'd Glafs, and fome other tranfparently colour. ed Bodies, appearing in one Pofition of one Co- lour, and of another in another, are on thefe grounds no longer Riddles. For thofeare Sub- | {tances apt to reflect one fort of Light, and tranfmit another ; as may be feen ina dark Room, _ by illuminating them with fimilar or uncompound- ed Light. For then they appear of that Colour only, with which they are illuminated ; but yet in one Pofition more vivid and luminous than in another, accordingly as they are difpofed more or lefs to reflect or tranfmit the incident Colour. 42. From hence alfo is manifett the reafon of am .unexpected Experiment, which Mr. Hook, fomewhere in his Micrography, relates .to vat
, made
oe is ke Rear Ra i Le Dee RR RM 2 5: ‘ ASHE A Sa a Sea
110 «Mifcellanea Gwiofa. made with two wedge-like tranfparent Veffels fill'd, the one witha red, the other with a blue Liquor ; namely, that though they were feveral- ‘ly tranfparent enough, yet both together became opake: For, if one tranfmitted only red, and the other only blue, no Rays could pafs through both. ma ras 13. I might add more Inftances of this Na- ture ; but F fhall conclude with this general — one, that the Golours of all natural Bodies have — no other Origin than this, that they are vari- oufly qualified to reflect one fort of Light in_ greater plenty than another. And this I have experimented in a dark Room, by illuminating thofe Bodies with uncompounded Light of di- vers Colours, For by thatmeans any body may be made to appear of any Colour. They have there no appropriate Colour, but ever appear of the Colour of the Light caft upon them; but yet with this difference, that they are moft brisk and vivid in the Light of their own day- light-colour. Minium appeareth there of any Colour indifferently, with which ‘tis illuftrated, — but yet moft luminous in red; and fo Bie ap- peareth indifferently of any Colour with which tis illuftrated, but yet moft luminous in blue. And therefore Minium’ refleéteth Rays of any Colour, but nfoft copioufly thofe endu’d with red , and confequently .when illuftrated with day-light, that is, with all forts of Rays pro- ‘mifcuoufly blended, thofe qualified with red, fhall abound moft in the reflected Light, and by their prevalence caufe it to appear of that Co- lour. And for the fame reafon Bife, refleAing blue moft copioufly, fhall appear blue by the ex- cefs of thofe Rays in‘its refleted Light; and. the like of other Bodies, And that this is: the | intire
lee Coat 3 by mn
Mifcellanea:Curiofa, 111 intire and adequate caufe of their Colours, is manifeft, becaufe they have no power to change er alter the Colours of any fort of Rays incident apart, but put on all Colours indiflerently, with which they are erilightned) Liccuct - 'Thefe things being fo, it can be no longer difputed, whether there be Colours in the dark, nor whether they be the Qualities of the Obs jects we fee, no nor perhaps, whether Light be a Body. For, fince Colours are the Qualities of Light, having its Rays for their intire and immediate Subject, how can we think thofe Rays Qualities alfo, unlefs one Quality may be the Subject of and fuftain another ; which in effe& is to call it Subftance? , We fhould not know Bo- dies for Subftances, were it not for their fenfible Qualities ; and the principal of thofe being now found due to fomething elle, we have as good -reafon to believe that:to be a Subftance alfo. - Befides, whoever thought any Quality to be aA heterogeneous Aggregate, fuch as Light is dif- ‘covered to be? But to determine more abfos —lutely, what Light is, after what manner re- _ fra&ted, and by what Modes or Aétions it pro- ~duceth in our Minds the Phantafms-of Colours, is not: fo eafie. And I fhall not mingle Con- jeCtures with Certainties. > xa Reviewing what! have written, I fee the Dit courfe irfelf will lead to divers Experiments fuf- ficient for its Examination ; and therefore I fhall ‘not trouble you farther, than to deferibe one of ‘thofe, which I have already infinuated. '* “In a darkned Room, make a hole in the fhut of a Window, whofe Diameter may conveni- ently be about a third part of an Inch, to admit _@ Convenient quantity-of the Sun’s Light : And there place a -clear ang colourlefs Prifm, 0 i fra
#
EM Age - te ‘|. | ad s @ ie : me ac i ak
112 Mifceilanea Curiofa.
frect the entring Light towards the farther part
of the Room; which, as I faid, will thereby be
diffufed into an oblong coloured Image. Then place a Lens of about three Foot Radius (fup- pofe a broad Object-glafs of a three Foot Tele-
- feope,) at the diftance of about four: or five Foot
from thence, through which all thofe Colours
may at once be tranfmitted, and made by its Re- fraction to convene at a farther diftance of abour ten or twelve Feet. If at chat diftance you in- tercept this Light with a Sheet of white Paper, you will fee the Colours converted into whitenefs again by being mingled. But it is requifice, that the Prifm and Lens be placed fteady, and_ that the Paper, on which the Colours are caft, be moved to and fro; for, by fuch motion, you will not only find at what diftance the whitenefs is mot perfect, but alfo fee how the Colours gra- dually convene, and vanifh into whitenefs ; and afterwards, having crofled one another im that place where they compound whitenefs, are again diffipated and fevered, and in an inverted order retain the fame Colours, which they had be- fore they entred the Compofition. Yau may al- fo fee, that, if any of the Colours at the Lens
. be intercepted, the whitenefs will be changed in- to the other Colours. And therefore, that the
“Compofition of whitenefs be perfect, care muft be taken that none of the Colours fall befides the Lens. } sae :
In the annexed Defign, Tab. 3. Fig. 2. of this Experiment, 4 BC exprefleth the Prifm fet end- wife to fight, clofe by the hole F of the Window EG. Its vertical Angle B C may convenient- ly be about 60 Degrees: M N defigneth the Lens, Its breadth 2} or 3 Inches. SF one of the ftreight Lines, in which difform Rays Bey
>: *
Mifcellanea Curiofa. = 113 be conceived to flow fucceflively from the Sun. FP, and FR two of thofe Rays unequally re- fracted, which the Lens makes to converge to- wards Q, and after decuflation to diverge again. And HI the Paper, at divers diftances, on which the Colours are projected, which in. Q conftitute Whitenefs, but are Red and Yellowin Ry r, and e, and Blue and Purple in P, p, and 7.
If you proceed further to try the impoflibility of changing any uncompounded Colour (which* I have afferted in the third and thirteenth Pro-
‘pofitions,) ’tis requifite that the Room,may be very dark, left any {cattering light, mixing with the Colour, difturb and allay it, and render it compound, contrary to the defign. of the Experi- ment. “Tis alfo requifite, that there be a per- fecter feparation of the Colours, than, after the manner above defcribed, can be made by the Refraction of one fingle Prifm ; and how to make fuch farther feparations, will fcarce be difficult to them, that confider the difcovered Laws of Re- fractions. But if trial fhall be made with Co- — Jours not throughly feparated, there muft be al- Jowed changes proportionable to the mixture. _ Thus if compound Yellow Light fall upon blue Bie, the Bife will not appear perfectly yellow, but rather green, becaufe there are in the yellow mixture many Rays indued with green, and green being lefs:remote frem the ufual blue Colour of i Bife than yellow, is the more.copioufly reflected BY itds5) .otOdwe «)coneyon13) , "In like manner, if any one of the Prifmatick _ Colours, fuppofe red, be intercepted, on defign ‘to’ try the» aflerted> impoflibility of reproducing _ that Colour, out; of the others which are preter mitted; tis necéflary, either thar the Colours _.be yery well parted before the red be intercep- : : ted ;
ert 114 Mifcellanea Curiofa.. ted ; or that, together with the red, the neigh- bouring Colours, into which any red is fecretly difpetfed, (that is, the yellow, and perhaps green too) be intercepted ; or elfe, that allowance be made for the emerging of fo much red out of the yellow green, as may poflibly have been diffufed, and: fcatteringly blended in thofe Colours. And if thefe things be obferved, the new Produr étion of red, or any intercepted Colour, will be ‘found impoftible. | This, I conceive, is enough for an Introducti- on to Experiments of this kind; which if any of the Royal Society fhall be fo curious as to profe- cute, I fhould be very glad to be informed with © What fuccefs: That, if any thing feem to be de- fective, or to thwart this Relation, I may -have an opportunity of giving farther Direction about it, or of acknowledging my Errors, if I have committed any. } q
Samana er YT at NN os ean as
Since the Publication of this Theory, fome Mifunder- ftandings happening between a French Philofopher at Paris and Mr. Newton, he has endeavour'd to explain himfelf a little further in thefe Things, according to the following Method.
OD) ee ENT oe
1. I call that Light Homogeneal, Similar, or |
Uniform, whofe Rays are equally refrangible.
“2. And that Heterogeneal, whofe Rays are unequally refrangible. nem |
Note, There are but three Affections of Light in which I have obferv’d its Rays to difler ; wiz. Refrangibilicy,Reflexibility, and Colour; and thofe _ “Rays which agree in Refrangibility, agree alfo - “4 in
Mijfcellanea Curiofa. IIs in the other two, and therefore may well be de- fined Homogeneal ; .efpecially fince Men ufually call thofe things Homogeneal, which are fo in all Qualities that come under their Knowledge, tho’ in other Qualities, that their Knowledge extends
“not to, there may poilibly be fome Heteroge- neity. ia
_ 3. Thofe Colours I call Simple or Homoge- neal, which are exhibited by Homogeneal ~ Light, , 4. And thofe Compound or Heterogeneal, which are exhibited by Heterogeneal Light. g. Different Colours, I call, not only the more eminent Species, Red, Yellow, Green, Blue, Purple, but all other the minuteft Gradations ; much after.the fame manner, that not only the more eminent Degrees in Mufick, but all the leaft Gradations, are efteem’d different Sounds.
PROPOSITIONS.
1. The Sun’s Light confifts of Rays differing by indefinite Degrees of Refrangibility.
2. Rays Which differ in Refrangibility, when —
parted from one another, do proportionally dif. fer in the Colours which they exhibir. Thefe Two Propofitions are Matter of Fa. _ 3. There are as many Simple or Homogeneal Colours, as Degrees of Refrangibility. For to every Degree of Refrangibility belongs a different Colour, ‘by Prop. 2. and that Colour is Simple, by Def. 1, and 3. |
4. Whitenefs, in all refpects like that of the Sun’s immediate Light, and of all the ufual Obs jects of our Senfes, cannot be compounded of twe Simple Colours alone, For fuch a Compofition
: Bah ee mut
116 Mifcellanea Curiofa. muft be made by Rays that have only two De- grees of Refrangibility, by Def. 1 and 3. and therefore it cannot be like that of the Sun’s Light. by Prop. 1. nor, for the fame Reafon, like that of ordinary white Obje&ts. abe ee 5. Whitenefs, in all refpeéts, like that of the Sun’s immediate Light, cannot be compounded of Simple Colours without an indefinite Variety of them. For to fuch a Compofition, there are , requifite Rays endu’d with all the indefinite De- grees of Refrangibility, by Prop. 1. And thofe infer as many Simple Colours, by Def. 1 and 3. and Prop. 2 and 3. ) Gels : To make thefe a little plainer, I have added alfo the Propofitions that follow. | ' 6. The Rays of Light do not a& on one ano- ther, in pafling through the fame Medium. 9. The Rays of Light fuffer not any change of their Qualities from Refra€tion. 8. Nor afterwards from the adjacent quiet Medium : Thefe two Propofitions are manifelt de Faéto-in Homogeneal Light, whofe Colour and Refrangibility is not at all changeable, either by Refraction, or by the Contermination of a quiet Medium. And as for Heterogeneal Light, it is but an Ageregate of feveral forts cf Homogeneal Light, no one fort of which fuflers any more alteration than if it were alone; becaufe the Rays act not on one. another, by Prop. 6. and there- fore the Aggregate can fufler none. Thefe two Propofitions alfo might be further proved’ apart, by Experiments too long to’ be here deicribed. _ 9. There can no Homogeneal Colours be re- duced out of Light by Refraction, which were not commixt in it before: Becaufeé by Prop, 7. and 8. Refraction changeth nor the Qualities of the Rays, but only feparates thofé which have Bs eh divers
Mifcellanea Curiofa. 117
divers Qualities, by means of their different Re- frangibility.
‘lo. The Sun’s Light is an 1 Aggregate of an indefinite variety of Homogeneal Colours, by Prop- i, 3, and.g.. And hence it is, that I call Homogeneal Colours alfo Primitive or Original. And thus much concerning Colours.
For a further Uluftration of this Dottrine, Mr. New- ton, i” bis Book of Opticks lately publifhed, has by undeniable Experiments explained moft of the Principal Phenomena of Light and Colours : To which we refer the Reader.
ees J /
118 Mifcellanea Curiofa.
A Demonftration concerning the Mo- tion of Light, communicated from
Paris.
Hilofophers have been labouring for many Years to decide by fome Experiment, whe- ther the Action of Light be conveyed in an in- ftant to diftant Places, or whether it requireth time. M. Romer, of the Royal Academy of Scien- ces, hath devifed a way taken from the Obferva- tions of the firft Satellit of Fupiter, by which he demonitrates, that for thediftance of about 2000 Leagues, fuch as is very near the bignefs of the Diameter of the Earth, Light needs not one Se- cond of Time. 7 cet Let (in Fig. 3. Plate 3.) A be the Sun, B Fu- piter, C the firft Satellit of Fupiter, which enters into the fhadow of Fupiter, to come out at D, and let EFGHKL be the Earth, placed at di- vers diftances from Fupiter.
Now fuppofe the Earth, being in L, towards the fecond Quadrature of Fupiter, hath feen the firft Satellit, at the time of its emerfion, or if- fuing out of the fhadow. at D, and that about
4ai Hours after (viz. after one Revolution of this Satellit) the Earth being in K, do fee it ree turn’d in D: It is manifeft, that if the Light require time to traverfe the Interval L K, the Satellit will be feen return’d later in D, than it would have been if the Earth had remained in L. Sothaithe Revolution of the Sarel/it being thus obferv’d by the Emerfions, will be uit 3 : de
Mifcellanea Curiofa. IQ
ded by fo. much time, as the Light fhall have
taken. in paffing from Lto K5 and that on the contrary, in the other. Quadrature. FG, where the Earth by approaching goes to meet the Lighr, the Revolutions of the Emerfions' will appear to be fhortned, by fo much as thofe of the Emer- fions had appear’d to be. lengthned. And be- caufe 422 Hours, which this Sareliit very near takes to make one Revolution, the diftance be- tween the Earth and Fupiter, in both the Qua- dratures, varies at leaft 210 Diameters of the. Earth: It follows, that if for the Account of every Diameter cf the Earth there were requi- red a, Second of Time, the Light wou'd take
32 Minutes for each of the Intervals G F, KL; which would caufé near half a quarter of an Hour between two Revolutions of the firft Sa- telit, one obfervd in FG, and the other in KL, whereas there is not obferved any fenable We i, te :
Yet doth it nor follow hence, that Light de- mands no time. For afrer M. Romer had exa- min’d the thing more nearly, he found that what was not fenfible in two Revolutions, became very confiderable in many being taken together ; and that, for Example, forty Revolutions obferved on the fide F, might be fenfibly fhorter, than forty others obferv’d in any place of the Zodiack where -Fupiter may be met with; and thar. in propor- tion of Fwenty two for the whole Interval of H E, which is the double of the Interval that is from hence to the Sun.
The neceffity of this new Equation of the Re- tardment of Light, is eftablifh’d by all the Ob- fervations that have been made in the Royal Academy, and in the Obfervatory, for the {pace of eight Years ; and it hath been lately confir-
: fie ar" med
igs
120 = Mifcellanea Curiofa. med by the Emerfion of the firft Satcllit obferv’d at Paris, the 9th of November laft, at § a-clock 35' 45" at Night, 10 Minutes later than it was to be expected, by deducting it from thofe thar had been obferv'd in the Month of Augu?, when the Earth was much nearer to Fupiter; which M. Roemer had predicted to the faid Academy from the beginning of September. | Hes
_ But to remove all doubt, that this Inequality is caufed by the Retardment of the Light, he de- montftrates, that it cannot come from any Exe centricity, or other Caufe of thofe that are com- monly alledged to explicate the Irregularities of the Mcon, and the other Planets; though he be wellaware, that the firft Satelit of Fupiter was — Excentrick ; and that, befides his Revolutions. were advanced or retarded, according as Fupiter did approach to or recede from the Sun; as al- fo, that the Revolutions of the Primum Mobile were unequal: Yet, faith he, thefe three laft Caufes of Inequality do not hinder the firft from being manifeft. | :
An
Mifcellanea Curiofa. 121
An introductory Effay to the Do-
_ rineof Sounds, containing fome Propofals for the improvement. of Acoufticks ; As it was prefented tothe Dublin Society, Nov. 12. 1683, by the Right Reverend — Father in God Narciflus Lord
- Bifbop of Ferns and Leighlin.
Bri to treat of the Doétrine of Sounds, I hold it convenient to premife fomething in the general, concerning this Theory ; which may ferve at once to ingage your Attention, and ex- cufe my Pains, when I fhall have recommended them, as beftow’d on. a Subject not altogether -ufelefs and unfruitful. 7 - And for this purpofe I fhall omit to fpeak any thing’ of the. Excellency of the Matter in Hand ; though it might be celebrated by Argue ments drawn from feveral Topicks, and_parti- cularly from this, that new Difcoveries and Ime provements may be made, both as to the Gee neration, Propagation and Reception of Sounds in- to the Senfe ; which, in a peculiar manner ae grees to this, above the Object of any other Senfe whatfoever. I fhall, [ fay , omit thefe things, and apply my felf wholly to the U/eful- nefs of the Theory, that we are now falling up- on, which I think cannot better be difcover- ed, than’ by making ‘a comparifon ’twixt the PY acid tae van , Senfes
Te Oh, ee ae ee ope? Oe
122 «©Mifcellanea Curiofa. Senfes of Seeing and Hearing, as to their Im- provements. Imean, by fhewing, that this lat-.. ter of Hearing is capable of all thofe improve- ments which-the, Senfé of Secing has. receiv’d from. Art, befides many more advantages that the Ear may ‘enjoy, by the help “of our ‘Do- ctrine, above-the’ Eye ; all which ‘moreover will be of as great benefit to Mankind, as any thing that Opricks have yet difcover’d, if not-of: grea- ter; which, with fome | other pre-eminencies that it. has’ upon another Score, will happi- ly render Azoufticks the nobler Science of the two. } LSet }
In order to the making good what I but;now — premifed of the Comparifon of thefe two Faculties of Seeing and Hearing, as to their Improvements, _T obferve; Mi) {S838 or ceed
That Vifion is threefold, Direét, Refrafted, and Reflex’d ; anfwerable whereunto we have .Opticks Dioptricks, and Catoptricks. | at a
In like manner Hearing may be divided. into, Dire&, Refraéted and Reflex’d , whereto, anfwer three parts of our Doctrine of Aconfticks, which. are yet namelefs, unlefs we call them. Acoufticks, Diacoufticks, and Catacoufticks, or ( in another. Senfe, but to as good Purpofe) Phonicks, Diapho- nicks, and Catapbonicks. 9 ‘ :
r. Direct Vifion has been improv’d two Ways, éx parte Objecti, and ex parte Organi vel Me- dii. | “> 1. Ex parti Oljetti, Direct Vifion has receiv’d. advantages by the Arts of Producing, Conferving. and Imitating Light and Colours, ‘which are. the Objects of Vifion. 7 : betes hoe -"t, For the Art of Producing Light, we have. the Frication of all hard Bodies) that beget. — Fire ; efpesially of the :Flint.and Steel ; ae | SIG Ee init
a Te Pant
4 >
Mifcellanea Curiofe. 123 inftead of the Flint, moft hard Stones (as well - _as the Cane) may be us’d to the fame effect, as upon trial 1 have found. Add hereto the lately ‘invented Phofphorus, which is a new and admi- rable way of producing a Lucid Subftance by Art, out of a Body in itfelf not Lucid; and therefore may not unfitly be term’d an Artificial produéion of Light. ? bare | And then of the Art of Conferving Light, the Lapis Bononienfis is a notable Inftance ; and fo happily were the Sepulchral Lamps of the An- cients. ele | ie ba - 2, As to Colours, “tis the greateft part of the. Art of Dying to be able to make and fix (that is — preferye) them; and the Painters and Limuners will own it to be no fmall part of their Skill to be able well to Mix (that is, in effect, to Gene- vate) Colours. ” wie 3. For Imitation of Light and Colours, ‘tis well known how far Perfpeétive with the Art of Limn- ing and Shadowing have gone therein, which all tend fome way to the Advance or Improvement of Direé Vifion. - : | Add to all thefe, That a due Applicaticn of Light to the Obje& renders it Vifible, if it were not fo before ; as appears from.a dark Room ‘i!- luminated, or elfe makes it better and more truly difcernable by the Senfe of Seeing, if before it _ might have been difcern’d. 3 | _ Hence the fame Co/ogr, in a diverfe Light, wiil appear different, andno Pi@yre can well be di- feern'd or judg’d of but by itstrue Light. Be- fides, the Limmer will aflure you, that he can hardly make true Work, or hit the Air of. a Face exactly, unlefs he draw by a North-Light, by reafon of the fteadinfs of that, and the uncertainty of all other Lights whatfoever. fh aa Which
124 Maifcellanea Curiofa,
Which things fhew, that the Art of duly applying Light to ehe Obje& does very much help and improve Vifion. So alfo does the due placing of the Oljc&, as to Height and Diftance. But to enumerate all things that help Direé Vifion, would be inf- nite. hon sO CUNGLE mann 2. Ex parte Organi vel Medii, Dire& Vifion has been improv'd by making ufe of a Tube, without Glaffes, or a Man’s clos'd Hand, to look thro’ ; which admitting into the Eye only the principal Rays, that come direétly from the Objeét, do very much ftrengthen and clear the Sight, by excluding all the Collateral Rays, that crouding — into the Eye, together with the direét. ones, — ‘would confound and difturb it, partly by mixing and interfering with the direct Rays, and partly -(or rather chiefly) by too much enlightning the fund of the Eye, wherein Vifion is truly (tho’ then imperfectly ). made. Nene os
On this is founded the Art of making Speéta- cles without Glaffes ; (as well as Tubes) which is done by putting into the Glafs-holes (inflead © of Glaffes) two fhort Tubes of between three . and four Inches long (for.their length is to be vary'd according to the Age or Eye of the Be- holder, and fo alfo is the Diameter of the exe tream ends) which Tubes being made of Spanifh — Leather (or Paft-board, or fome fuch like Mat- ter) and black’d on the infide, are fo to be pla- ced, as that the vifual Rays, receiv’d thro’ them, - may meet in one point (or rather iffue out from one Point) of the Object ftanding at fuch a due _ diftance, as.the Perfon may clearly and diftinéily ~ fee it, or according to his length of Sight (as
ABC, inthe 4th Fig. Tab 2.)
And
—— Mifcellanea Curiofa. 128 And thefe Speétacles may be fuppos’d better for preferving the Sight, than the ordinary ones
with Glafles, becaufe they reprefent the Object more naturally, and withal more clearly and di- ftinétly to the Eye, than the other, whofe refract- ed Rays being collected together with the right ones in the Glafles, do fomewhat confound good Vifion, as before: Efpecially if the vifive Power be ftrong enough to be fufhiciently determin’d by the right Rays alone. 3 _. For I fpeak now of preferving a good Eye by thefe Spectacles, which holds in proportion true aifo of a bad one. Becaufe thofe Rays (both right and refracted) being collected and brought fo near the Eye (whether good or bad} as the Spectacles are ulually piac’d, do too much affeét it, both by their own brightnefs, and alfo by the brightnefs of the Colours of the Object - (when they are bright) which is brought very near alfo ; whereby the Eye is dazl’d and con- founded, unlefs there be a ftrong attention and conatus of the Spirits, .whereto the bright Rays do certainly engage them, which of necetlity weakens Vifion, efpecially if thefe Glafs-{peQa- cles be much us’d. 7 ~ Wherefore the now defcrib’d new Tube-fpetta- cles, contributing fo much to the help and pre- fervation of Sight, may well be counted an im- provement of Direé Vifion, becaufe they convey _ the Rays tothe Eye without any kind of Refracti- on whatfoever, Seeing the fame , Object alto through various holes, plac’d at certain diftances, does fomewhat alter Vifion ;. but of this perhaps more hereafter. -— ¢ > Now as Direé& Vifion has thus been impro- ved, fo likewife Direét Hearing partly has al- — ready receiy'd, and partly may (by the Dodtrine ‘ae ee whereof
SN TRESS Eis ORIN ae er it
126 = Mifcellanea Curiofa. whereof we are treating, (if well cultivated) far- ther receive as great and notable Improvements, _ both ex parte Objecti, and ex parte Organi vel Medii. — | ! - #. As to the Odje& of Hearing, which is © Sound, improvement has been and may be made, both as to the Bezettimg, and as to the Conveying and Propagating (which is a kind of Conferving) of Sounds. : faern ie 1. As to the Begetting of Sounds. The Art of imitating any Sound, whether by Speaking'(that is pronouncing) any kind of Language, (which really is an Art, and the Art of Speaking, perhaps one of the greateft) or by Whiffling, or by Sing- ing (which are allow’d Arts) or by Hollowing or — Luring (which the Hunt{man or Faulkner would — have to be an Art alfo) or by imitating with the Mouth (or otherwife) the Voice of any Animal, as of Quails, Cats, and the like; or by repre- | fenting any Sound begotten by the Collifion of Solid Bodies, or after any other manner; thefe are.all Improvements of Dire& Hearing, and may be improv’d. | eee Moreover the Skill to make all forts of Mua- fical Inftruments , both Ancient and’ Modern, whether Wind Inftruments or String’d, or of any other fort, whereof there are very many © (as Drums, Bells, the Syftrum of the Egyptians, and the like} that beget (and not only propa- gate) Sounds; the Skill of miaking thefe, I ~ fay, is an Art, that has as much improv’d Dire& Hearing, as an Harmonious Sound exceeds a fingle and rude one, that is, an immufical Tone ; which Art is yet capable of farther improve- ment. And I do hope, that by the. Rules, which may happily be laid down concerning the Nature, Propagation and Proportion, or A- ‘ | dapting
Mifcellanea Curiofa. 197 dapting of Sounds, away may be found out, both to improve Mufical Inftruments already in ufe, and to invent new ones, that fhall be more {weet and lufcious, thanany yetknown. Befides thar, by the fame means Inftruments may be made, that fhall imitate any Sound in Nature, that is not Articulate, be it of Bird, Beaft, or what thing elfe foever.
2. che Conveying and - Propagating (which is a kind of Conferving) of Sounds, is much help’d by duly placing the Sonorous Body, and alfo by the Medium.
For if the Medium be Thin and Quiefcent, and the Sounding Body placd conveniently, the Sound will be eafily and regularly propagated, and mightily conferv’d. I fay, ‘au
1. lf the Medium be Thin and Quiefcent, becaufe it otherwile caufes a Refrafed Sound, of which afterwards, Hence in a ffill Evening, or the dead of the Night (when the Wind ceafes) a Sound is better fent out, and to a greater diftance than otherwife,- tho’ much of this may be afcrib’d to its Refra&ion-alfo. hag ie
2. I fay, thatthe Sonorous Body muft be plac’d convenicntly, neat a Smooth Wall, near Water, ot a Plain, whofe Surface is even. :
I. Near a Smooth Wall, either Plain or Arch’d (Cycloidically or Elliptically, rather than other- (wife, tho’ a Circular or any Arch will do, but met towel) socch sci, '
- ) Hence! ina Church, the nearer the Preacher
ftands,to the Wall-(and certainly ’tis much the
belt way to place Pulpits near the Wall) the better is he heard, efpecially by thofe who ftand
smear the Wall alfo, though at a greater di-
fance. from the Pulpit; thofe. ar the. remoreft
~endof the.Church, by laying .their Ears ‘one hey: : what
BUT Re ea a TER OES Ne ea
12% =©Mifcellanea Curiofa. what clofe to the Wall, may hear him eafier than thofe in the middle. | | Hence alfo do arife Whifpering Places. Fur the Voice being apply’d to one end of an, Arch, eafily rowls to the other. And indeed were the Motion and Propagation of Sounds but rightly un- derftood, ’twould be no hard matter to contrive © Whifpering Places of infinite variety and ufe. And _ perhaps there could be no better er more pleafane hearing a Confort of Mufick than at fuch a place as this, where the Sounds rowling along toge- ther, before they come to the Har, muft needs confolidate and imbody into one ; which becomes a true compofition of Sounds, and is the very Life and Soul of Confort. a4 2. If the Sonorous Bady be placd near Wa- ter, the Sound will eafily be convey’d, yet mol- lified ; as Experience teacheth us from a Ring of Bells near a River, and a great Gum fhot offat Sea, which yet differ much in the ftrength, and {oftnefs and continuance, or propagation of their Sounds, from the fame at Land, where the Sound js more harfh and more perifhing, or much foon- er decays. 3 | ty 3. Ina Plain a Voice may be: heard at a far greater diftance than in uneven Ground. La The Reafon of all which laft nam'd Phenome- na is the {ame ; becaufe the Sonorous Air meet- ing «with little or ‘no refiftance-upon'a Plane (much lef§ upon an Arch’d) fmooth Superhcies, eafily rowls along it, without being’ let of hin- der’d in its Motion, and confequently ‘without having its “parts disfigured, and put into ano- ther kind of Revolution, than what they had “at the firft begetting of the Sound. “W hich is ‘the true caufle of its Prefervation ot Progreffion, ‘and fails much when the Air pafles over an un- | even
Mifcellanea Curiofa. 129 even Surface, according to the degrees of its in- equality, and fomewhar alfo, when it pafles over the plain Superficies of a Body that is hard and refitting. }
Wherefore the fmooth Top of the Water (by reafon of its yielding to the Arch’d Air, and gently arifing again with a kind of Refurge, like to Elafticity, tho’ it be not fo, by which Re- -furge it quickens and haftens the motion of the Air rowling “over it, and by its yielding pre- ferves it in its Arch’d Cycloidical or Elliptical Fie gure) the fmooth Top of the Water, Lfay, for thefe Reafons, and by thefe Means, conveys a Sound more entire, and to a greater diftance © than the plain Surface of a piece of Ground, a Wall, or any other Solid Body-whatever, can
0.
As forthe Speaking Trumpet, by which a Voice may be convey’d to a confiderable diftance, I re- fer its confideration to that of Refraéted Sounds, or Refratted Audition. | __ Thus much of the Improvements of Hearing,
that refpe its Objet?, which is Sound. 2 The Organand Medium are to be canfider’d. And, 1. The Organ, which is the Ear, is helpt much by placing it near a Wall (efpecially at one end of an Arch, the Sound being begotten at the other) or near the Surface of Water, or of the Earth, along which the Sounds are moft eafily and naturally convey’d, as was before declar’d. And ’tis incredible how fara Sound made upon the Earth (by the trampling of a Troop of - of Horfes, for Example) may be heard ina ftill Night, if a Man lays his Ear clofe to the Ground in a large Plain.
es Oracou=
130 «©. Mifcellanea Curiofa. — Oracoufticks here come in for helping the Ear 5 which may be fo contriv’d (by a right under. ftanding the Progreffion of Sounds, which is the principal thing to be known for the due regula= ting all fuch kinds of Inftruments) as that the Sound might enter the Ear without any Refradti- — on, but as now they are generally madeI refer them to Refratted Audition. | V4 2. Asto the Medium, I know not how that, by any contrivance of Art, can advantage Di- re& Hearing, otherwife than I have declar’d alrea- dy in the propagation or conveyance of Sounds, though tothe Refracting or Refle€ting of them it may very much conduce ; of which prefent«
; And fo 1 have done with the firft part of my prefent undertaking, which is the Comparifon of Dire& Vifion and Audition, as to their improve- ments from Art. The reft follow: Where- fore, | | aa ts
II. Concerning Refra&ed Vifion and its Com- parifon, I obferve, That Refrated Vifion 1s al- ways made Ex parte Medit, as RefleBed is ex parte Olje&i. And therefore, though Dire& Vifion may be help’d ex parte Objelti, Medii vel Organi, yet Refratted can be improv’d only ex parte Me= dit, and Refletted ex parte Corporis oppofiti alone, —Uniefs it be in-a mixt or compound Vifion, that is Refraéto-Reflext, when the reflext Rays pafs to the Eye through a refraCting Medium, fuch as the Medium Internam, contain’d in the Body of the Eye, always is. Sothat in truth, all Vifion is Refratted by an internal Refraétion made in ipfo Oculo. | we
And ©
oo test lin ie ll ba t
Mifcellanea Curiofa. 131
And all that I have fpoken of Von holds true
of Hearing alfo, both Refratted and Reflexty and therefore need not be repeated, |
Refratted Vifion arifes from the different Den= fitys Figure, and . Magnitude of the Medium, which is fomewhatalter’d alfo by the diverfe ie cidence of the vifible Rays. And fo it is in - Refratted Hearing, all thefe Caufes concur io its ProduGtion, and fome others to be hereafter _confider’d. Ta _ Now as any Obje& (a Man for example) feen through a thicken’d Air, by RefratEion appears greater than really he is : So likewife a Soundy heard through the fame thicken’d part of the Atmofphere, will be confiderably vary’d from what it would feem to be, if heard through a | thinner Medium.
And this.] calla Refraéted Sound : But whae this RefraGtion of Sound is, and how causd, may hereafter be difcufs'd, when the Nature, and Motion, or Progreflion of Sounds are well fated)
For the Improvement of Refratted Vifion ar= tificial Inftruments have been made, by grinding or blowing Glaffes, into a certain Figure, and placing them at due diftances, whereby the Ob- jet may be (as ’twere) enabled to fend forth its Rays more vigoroully, and the Vifive Fa- culty impower’d the better to receive them.. And thus alfo Inftruments may be contriv’d for the affitting both the Sonorous Body, to fend forth its Sound more ftrongly, and the Acoy- flick, Faculty, to receive and difcern. it more eafily and clearly, For, Li ay
1. As a fine Gjafs Bubble, fill’d with clear Wa. ter, and placed before a burning Candle or Lamp, does help it to dart forth its Rays to a BA oS K 2 prodigious
/
ORE APRS Nae Beige! bg TS acs Styles tate ¥ ye
132 Mifcellanea Curiofa. prodigious Length and Brightnefs : So an Ine. ftrument may be invented, that apply’d to the. Mouth (or any Sonorous Body) {hall fend forth the Voice diltinétly to as prodigious a Diftance and Loudnefs. | : PCa For if the Stentore-phonecon (which is but. a rude and unartificial Inftrument ) does fuch great feats, what might be done with one com- posd according to the Rules of Art ? whofe — make fhould comply with the Laws of Sonorous Motion (which that does not). and therefore not fs much Refract, as to alter and confound the. Tone of the Voice and Words (as that fomewhat does. ) : Ly ale he Now of what ufe fuch an Inftrument might be for fpeaking clearly and articulately at a di- {tance (and that without altering the Tone of the Voice) whether it be at Sea or at Land (but efpecially at Sea in tempeftuous Weather and in the Night) is obvious to any Man to con- ceive. es, han 2. As Inftruments have been invented to help the Eye, So likewife are there fome, and more fach there may be, for the Ear. . bola For, eas rei sles at 3 1. As Spectacles and other Glaffes are made to. help the Purblind and weak Eyes, to fee at any — competent diltance: So there are Osacoufticks — (ana better may be made) to help weak Ears to | hear at a reafonable diftance alfo. Which would be as great a help to the infirmity of Old Age, as the other invention of SpeCtacles is, and perhaps grearer ; forafmuch as the Hearing what’s fpoken is of more daily ufe and concern to fuch Men, then to beable to read Books or to view Pi-) Efures. | | i}
-—— Mifcellanea Curiofa. 133 2. As Per/peétive-Glaffes and Telefcopes help the Eye to fee Objects at a very great diltance, which otherwife would not be difcernable ; in like manner may a fort of Oraooufticks be fo contriv’d, -asthat they fhall receive in Sounds made at a very great diftance allo, but with fo much advantage, that the Ear fhall be able to hear them, which o- therwife would have been inaudible, And thefe Oracoufticks in fome refpects would _ be of greater ufe than Per/peétives. For whereas at Land Pei/peétives are mahy times render’d al- meft ufelefs, by the interpofition of Woods and Mountains, which hinder the Sight from reach- ing very fat: Our Otacoufticks would, notwith- ftanding thefe Obftacles, take in a Sound made fome Leagues off. . Which might be of notable ufé in the time of War, for difcovering the Enemy at a good diftnnce, when be marches or lyes in- camp’d behind a Meuntain or Wood, or any © fuch place of fhelrer. - Yea, even at Sea alfo, where Per/peftives are of moft ufe, by reafon of the plainefs of the Surface of the Water ; yet fometimes there O- tacoufticks may be of more benefit, when in dark hazy Weather the Air is too thick, or in Stormy ‘Tempeftuous Weather the Waves arife too high for the: Perfjeftive to be made Heo > sgcicy! : ihe But, whether at Sea or Land, Perfpettives. be- ‘come altogether: infignificant -in the Night-time (unlefs it be for viewing the Stars) which is the chief time for ufing Oracoufticks 5 as it is generally, for Soldiers to take their March, when they would ieprite:cheir Enemies? ort cyielyr decison And therefore this fort of O+acouftichs: .baye then their chief ufe, when Per/petfives are of no K 3 ule
sin rere
>
PA: ie CO a ane ay ae ka He Sati TA ak pc: : Se Uh ciel EMBO
134 Maifcellanea Curiofa. ufe at all; befides that they may be imploy’d in the Day-time, as well as Per/peftives, whence they may (not unfitly) be term’d the moft ufeful Inftrument of the two. i
3. As Microfcopes or Magnifying-Glaffes help the Eye to fee near Oljeés, that by reafon of their {mallnefs were Iivifble before ; which Ob- jects they Magnify to a ftrange greainefs.: So Microphones or Micracoufticks, that is Magnify-
ing Ear Inftruments, may be contriv’d after that
manner, that they fhall render the moft minute _. Sound in nature diftin@ly audible, by Magnify- ing it to an unconceivable loudnefs.
By the help hereof we may hear the different Cries and Tones, as well as by Microfcopes fee the divers Shapes and Figures of the fmalleft Ani- mals, aan one
4. As by Polyfcopes or Multiplying-Glaffes, one thing is reprefented tothe Eye as many, whe- ther in the fame or different Shapes (for fo Multiplying-Glafles may be contriv’d:) So by a Polyphone or Polyacouftick well order'd, one Sound may be heard as many, either of the fame or a different Note. Infomuch, that who ufes this Tnftrument, he fhall, at the Sound of a fingle Viol, feem to hear a wholé Confort and all true Harmony. By which means this Inftru- ment has much the advantage of the Poly- feope. : v Ae And thus much may fuffice for comparing the - Improvements made’ upon Refratted Seeing and Hearing ; 1 call it Refratted Hearing, becaufe made through a Medium, viz. thick Air, or an Inftrue — ment, through which the Sound pafling is broken or refracted. fy Stee! bre 4"
TW: Reflfted
Mifeellanea Curiofa. 135
TLL Refletted Vifion has been improw’d by the Invention of Looking-glaffes and Polifh'd Metals, whether Plane, -Concavey or Convex ; and thefe — two laft, either Spherical, Oval, Cylindrical, Co- nical, Hyperbolical, ox of feveral other fhapes ; all which caufe a different Reflection, and vaty the Phenomenae : - Thus alfo Reflext Audition, made by Ecchoes, may be improv’d, by contriving feveral forts of Artificial Ecchoes ;.as ‘tis no hard matter to do in almoft any place. — : ve.
_ For (fpeaking in the general) Any Sound, fall- ing direétly or obliquely upon any denfe Body, of a Smooth. (whether Plane or Arch’d) Superficies, is beat back again and refictted, or does eccho more or left.
_ I fay (1.) falling dire€tly or obliguely 5 becaule, if the Sound be fent out and propagated parallel | - to the Surface of the Denfe Body, or be made fo far off and fo weak, ‘that it cannot reach it, there will be no Reflection of Sound,no Eccho.
_ I fay (2.) upon a Body of a fmoo'h Superfi- cies ; becaufe if the Surface of the Corpus Ol- fians be uneven, the Air by reverberation will be put out of its regular Motion, and the Sound thereby broken and extinguifh’d : So that tho’ in this cafe alfo the Air be beaten back again, yet Sound is not reflected, nor is there any Eccho.,
+0 fay ( 2.) it does eccho more or lefsy to fhew, _ that when all things are, as is before defcrib’d, there is ftill an Ecchoing, though it be not al- waysheard ; either becaufe the dircft Sound is too weak to be beaten quite back again to him that made it ; or that it does return home to him, but fo weak, that without the help of a good Oracouftick it cannot be difcern’d ; or that i K 4 he
136 Mifcellanea Curiofa.
he ftands in a wrong place, to receive the refle- ~
éted Sound, which paffes over his head, under. his Feet, or to one fide of him ; which therefore may be heard by a Man ftanding in that place, where the reflected Sound will come, provided no interpos'd Body does intercept it ; but not by him, that-firft made it. " cera th I fhall further make out the comparifon “twixt Reflex'd Vifion and Audition, by thefe following Propofitions. Sag 1. As a Plain Speculum reflects the Objeé& in its due Dimenfions and Colours ;_ allowing for
their difference of appearance, according to their -
diftance: So a Plane Corpus Objtans reflects the Sound back in its due Tone and Loudnefs 3; if al- lowance be likewife made for the proportiona- ble decreafe of the Sound, according to its di-
ftance. ‘
2. As a Convex Speculum reflects the Obje&
lefs, but fomewhat brighter or clearer: Soa
Convex Corpus Obftans repels the Sound (infenfi- _ bly) /maller ; but fomewhat quicker (though wear
ker) than otherwife it would be. 3. As a Concave Speculum refle&s the Object bigger, more obfcure and Inverted: So a Concave
Corpus Obftans ecchoes back the Sound (infenfi-
bly) bigger, flower (though ftronger) and alfo inverted ; but never according to the order of Words. Nor do I think it poflible for the ‘Art of Man to contrive a Single Eccho, that: fhall
invert the Sound, and repeat backwards ; be-
caufe then the Words laft fpoken, that is, which do laft occur to the Corpus Obftans,; mult firft be repell’d ; which cannot be : For where, in the mean time, fhould the firft Words hang, and be conceal’d, or lie. dormant ? Or how, after fuch a paufe, be reviv’d and’ animated’ again
. inta
Ree
Mifcellanea Curiofa. 139 into Motion? Yet in complicated or Compound Ecchoes, where many receive from one another, I know not whether fomething that way may not be done. — . |
from the determinate Concavity or Arched- nefs of thefe reflecting Bodies, it comes to pal that fome of them, from a certain diftance or poft- ture, willeccho back but one determinate Note, and from no other place will they reverberate a- | ny ; becaufé of the undue Pofition of the found- ing Body. Such an one (as I remember) is the Vault in Merton College in Oxford.
4. As a Speculum takes in and reflects more of its Object, when placd at a great diftance from it, than when nearer; becaufe it reflects according to’ the apparent Magnitude of the Body at fuch a diftance, which is lefs: So alfo the Ecchoing Body, being remov’d farther off, re- fle&ts more of the Sound, than when nearer. And this is the reafon, why fome Ecchoes repeat but -one Syllable, fome one Word, and fome many.
5. As Specula’s may be fo plac'd, that refle&t- ing one upon or into the other, either directly or obliquely, one Object fhall appear many ; as in Sir Samuel Moreland’s Glafs-room : After the fame manner Ecchoing Bodies may be fo contriv’d and plac’d, asthat refleing the Sound from one to ‘the other, either directly and mutually, or ob- Tiquely and by Sticceflion, out of one Sound fhall ‘many Ecchoes be ‘begotten; which in the firit cafe will be all together, and fomewhat -in- wvolvd or fwallow’d up of each other, and | thereby .confus’d (as a Face in Looking-glafles obverted) in the other they will be diftinét, fepa- fate, and fucceeding one another 3 as moft mul- tiple Ecchoes do, a ba
Moreover
138 = Mifcellanea Curiofa.
Moreover a Multiple-Eccho may be made, by
fo placing the Ecchoing Bodies, at unequal di- ftances, that they reflect all one way, and not one on the other ; by which means a manifold fucceflive Sound will be heard ( not without “laggpachente ) one Clap of the hands like many, e Ha, like a laughter, one fingle Word like many of the fame Tone and Accent, and fo one Viol like many of the fame kind imitating each —
other. | |
Furthermore, as Specula’s may be fo order’d, that by Refleétion they fhall make one fingle thing appear many different things ; as one fingle Man to feem many Men, differing as to Shape and Complexion (or a company of Men) which I think Sir Samuel Moreland’s Contrivance does not : So may Ecchoing Bodies alfo be order’d, that from any one Sound given, they fhall produce many Ecchoes, different both as to their Tone and Intenfion. (The ground whereof has elfewhere been laid down in a ‘Treatife concerning the Sym-
: pathy of Lute-ftrings.) * By this means a Mufical Room may be fo con- triv’d, that not only one Inftrument, play’d on in it fhall feem many of the fame fort and fize ; but even a Confort of (fomewhat) different ones ; only by placing certain Ecchoing Bodies fo, as that any Note (play’d) fhall be return’d by them in. ds, sths, and 8+hs, which is pofhible to be done otherwife than was mention’d before in Re- fratked Audition. ie Lit CO ae I have now done with my Comparifon of the two Nobleft Senfes, and Sciences, as to their Im- provements ; wherein I have been thus large, that I might give you a little profpeé& into the Excellency and Ujefulnefs of Acoufticks 5 atid that thereby I might excite all that hear me, to cs sed ther
Mifcellanea Cuviofe. 139 their Thoughts towards the making of Experi- ments for the compleating this (yet very imper- fe, tho’ noble) Science ; a Specimen whereof J will give you in three Problems, and then pre- fent you with the Semiplane of an <Acouftick or Phonical Sphere, as an Attempt to explicate the great Principle in this Science, which is The Pyo- greffion of Sounds.
The Problems are thefe :
1 Sonum intendere quoufque velis 5 Of, Datum fonum ad datum gradum intendere. 2. Sonum extendere quoufque velw ; or, Datum fonum ad datum diftantiam extendere feu propa- gare. ; j 3: Sonum tranfire ab extremo ad extremum & non per Medium.
1. The firft is, To make the leaft Sound (by the help of Inftruments) a loud as the greateft ; a whifper to become as loud as the fhot of a _ Cannon. ;
By the help of this Problem, the moft minute Sounds in Nature may be clearly and diftinly heard. _ : "
2. The fecond is, To propagate any (the: leaft) _ Sound to thegreateft diftance. Us | ' By the help hereof any Sound may be con- yey'dto any, and therefore heard at any diftancé, (I muft add, within a certain, tho’ very large _ Sphere.) Fatt ON ae _ Moreover, by this means, a Wearher-cock ‘may be fo contriv’d, as that with an ordinary blaft of Wind it fhall. cry (or whiftle) loud e- nough to be heard many Leagues : Which hap- pily may be found of fome ule, not only for Pi- ; LN ly awe re tots
(140 = Mifcellantea Curiofa,
lots in'mighty tempeftuous Weather, when /igh? Houfes are render'd almoft ufelefs; but alfo for the meafuring the ftrength of Winds, if allowance be made for their different moifture. © For 1
conceive, that the more dry any Wind is, the
louder it will whiftle ceteris paribus ; Ufay, cae- zeris paribus, becaufe, befideg the ftrength and drynefs of Winds or Breat&, there are a great
many other things (hereaftgr to be confidered) —
that concur to the incréafe or magnifying ‘of Sounds, begotten by them in an Inftru-
ment expofed to their Violence, or blown in- —
to
one diftant place to another) fo as not to be heard an the middle.
_ By the help of this Problema Man may talk to his Friend at a very confiderable diftance, fo that thofe in the middle fpace fhall hear nothing of what paffed becwixt them. we}
FIG. V. TAB. IL Semiplanum Sphara Phonica feu Acouftice.
You are to conceive that (rude) Semiplane,
20 The third Problem, is, That a Sound may be conveyd from one extreme to the other (or from
as parallel to the Horizon : For if it be per- -
pendicular thereunto, I fuppofe the upper ex- tremity will be.no longer Circular, but Hyperbo-
lical, andthe lower part of it fuited to a grea- —
— ter Circle of the Earth, So that the. whole Phonical. Sphere (if I may fo call it) will be a folid Hyperbola, ftanding upon a Con- cave Spherical Bafe. 1 {peak this, ‘concern ing Sounds made (as ufually they are) nigh the
; Earth,
a a So RD ae RED
Mifcellanea Curiofa. IAI
Earth, and whofe Sonorous Medium has a free paflage every way. For if they are generated high in the Air, of dire&ted one way, the cafe will be different; which is partly defign’d in the
inequality of thar Draught.
raat Mifcellanea Curiofa.
A Difcourfe concerning the Modern Theory of Generation, by Dr. George Garden of Aberdeen, being part of a Letter to Dr. Wil- — liam Mufgrave, L. L. D. Reg. Soc. S. and by him communicated the Royal Society. =
“1H E Subje& I pitch upon, is that of the oP Formation cf Animals. You know how wide and unfatisfying Men’s Conjeftures were | upon this Head, until this Age, in which firlk the defervedly Famous Dr.. Harvey difcovered the proper place of the Formation of the Chick in the Cicatricula of the Egg, and the Forma- tion of the Parts fo far as was difcernable by the naked Eye; and after him Malpighius, by the help of exact Glaffes, obferv’d the firft Rudi- ments of it there, both before and after Incuba- tion : And R. de Graef, and others, having upon many Obfervations concluded, that the Tefies Fminei were the Ovaries of Females, and confequently that -all Animals were ex-ovo; they began from hence to infer, that the Rudiments of each Animal were originally in the refpective Females, and that the Male contributed only to give a new Ferment tothe Mafs of the Blood and Spirits, by which means a fpirituous Li- ~ quor (which the Blood in its ordinary Ferment could not produce) did infinuate it felf into
: the
i oe . Mifcellanea Curiofa. 143 the fame Duéts and Pores of the Rudiments of — thofe Animals, which were in greateft forward-
nefs in the Ovary, and fo extend and enlarge all their Parts, and at laft bring them to per- feétion, as Mr. Perrault does ingenioufly dif- courfeinthe third Partof his Efais de Phyfique 3 till now at laft Leowenboek, has difcover’d an in- finite number of Animalcula in femine marium ot all kinds, which has made him condemn the former Opinions about the Propagation of all Animals ex Ovo. |
Now upon comparing the Obfervations and Difcoveries which have been made with one a- nother, thefe three things feem tome very pro- bable. 1. That Animals are ex Animalculo.. 2. That thefe Animalcles are originally in femine Marium €3 non in Feminis, 3+ That they can never come forward, nor be formed into Ani- mals of the refpective kind, without the Ova in Faminis. | : hg
The firft of thefe feems probable from_ thefe three Obfervations. 1. “That fome fuch thing has been fo often obfervd by Malpighius, in the Cicatricula of an Egg before Incubation, as the Rudiments of an Animal in the fhape of a Tadpole, as may be feen in his firft, and in his repeated Obfervations de formatione Puli in Ovo, 2. The fudden appearance and difplaying of allthe Parts after Incubation, makes it pro- bable, that they are not then aétually formed out of a fluid, but that the Stamina of them have — been formerly there exiftent, and are now ex- panded. The firft Part of the Chick which is difcovered with the naked Eye, is, you know, the Panétum faliens, and that not till three days and nights of Incubation be paft ; and then, ne
t
NSN ARE Ch ORE SSS os ae ge 2 fae 4 Reh,
144 Mifcellanea Curiofa. the fifth day, the Rudiments of the Head and Body do appear; ‘This made Dr. Harvey con- clude, that the- Blood had a being before any other Part of the Body 3 and that from it, all the Organs of the Fetus were both form’d and nourifhed : But by Malpighius’s Obfervations we find that the Parts are then only fo far ex- tended, as to be made vifible to the naked Eye, and that they were actually exiftent before, and difcernable by Glafles. After an Incubation of thirty hours, are to be feen the Head, the Eyes, and the Carina with the Vertebra, diftiné:, and the Heart. After forty hours its Pulfe is vifi- ble, and all the other Parts more dittin@, which cannot be difcerned by the naked Eye before the beginning of the fifth day ; from whence it feems probable, that even the fo early difcove- ry of thofe Parts of the Fwetus by the Microf- cope, is not the difcerning of Parts newly for- med, but only more dilated and extended by receiving of Nutriment from the Colliquamentum ; fo that they feem all to have been actually ex- iftent before the Incubation of the Hen. And what Swammerdam has difcovered in the tranf- formation of Infeéts, gives no {mall light to this ; whilft he makes appear in the Explana- tion of the 13th Table of the General Hiftory ot Infe&ts, that in thofe large Eruca’s which feed upon Cabbage, if they be taken about the time they retire to be transformed into. Aurelia’s, and plung’d often in warm Water to make a Rupture of the outer Skin, you will difcern through the tranfparency of their fecond Mem- brane, all the Parts of the Butterfly, the Trunk, Wings, Feelers, €c. folded up. But that af- ter the Eruca is chang’d into an Aurelia, none of thefe Parts can be difcern’d, they are fo oe 3 drenche
Mifcellanea Curiofa. 145 drencht with moifture, tho’ they be there actual- ly form’d. Another Confideration is from the Analogy, which we may fuppofe between Plants and Animals. All Vegetables we do fee proceed ex Plantula, the Seeds'of Vegetables being no- thing ‘elfe but little Plants. of the fame kind folded up in Goats and Membranes ; and from hence we may probably conje@ure, that fo cu- rioufly an organized Creature as an Animal, is not the fudden Produd&t of a Fluid or Colliqua= mentum, but does much rather proceed from an Animalcle of the fame kind, and has all: its _lit- tle Members folded up according to their feve- ral Joints and Plicatures, which are afterwards enlarged and diftended, as we fee in Plants. - Now tho’ this Confideration alone may feem
motto bear much weight ; yet being join’d to the two former, they do mutually: ftrengthen
each other. And indeed all the Laws of Mon _ tion, which are as yet difcovered, can give bu- a very lame account of the forming of a Plant or Animal. We fee how wretchedly Des Cartes came off when he began to apply them to this Subject; they are formed by Laws yet unknown to'Mankind ; and. it feems molt probable, that the Stamina of all the Plants and Animals that have been, or ever fhall be in the World, have been form’d, ab Origine Mundi, by the Almighty Greator: within the firft:of each refpective kind, Andhe who confiders the: Nature of Vifion, that at does not give us the true magnitude, but the | proportion of things ; and: that what feems to our
naked’ Eye but a Point, may truly be made up of as many Parts as feem tous to be in the whole ifible World, will not: think this an abfard or _ imipoffible thing, © ee:
hed i> But
146 = =Mifcellanea Curiofa.
But the fecond thing which later Difcoveries have made probable, is, that thefe Animalcles are originally in Semine Marium & non in Femi- nis. And this I colleét from thefe Confidera« tions: 1. That there are innumerable Animai- cula difcover’d in Semine Mafculo omnium Ani~ malium. \Mr. Leewenhoeck has made this fo evi- dent by fo many. Obfervations, that I do not in the Jeaft queftion the truth of. the thing, The reafon of their Multitude, and fome of the Difficulties which arife thereupon, he has. clear- ed to very good Purpofe, fo that I fhall not re- peat them. 2. The obferving the Rudiments of the Fetus in Eggs, which have been. fecun- dated by the Male; and the feeing no fuch thing . in thofe which are-not fecundated, as appears from Malpighius his Obfervations,.make it very. probable that thefe Rudiments proceed origi- nally from the Male, and not from the Female. 9. The refemblance between the Rudiments of the Fwtus in Ovo, both before and after Incu- bation, and the Animalcle, makes it.very pros bable, that they, are -one and the fame. »The fame Shape -and: Figure .which. Mr. Leewenhoeck gives us of the \Animalcle, :Malpighius likewife gives of the Rudiments | of the» Fetus, both be-- fore and after Incubation ; yea, and even: the Fetus of Animals do appear fo\at firft. to the naded Eye, fo that Dri Harvey does acknows ledge that all Animals, even) the, moft perfec, are begotten of a Worm,.De Gen. Anim. Ex. 18. 4. This gives a rational account of many Fetus’s at one Birth, efpecially that of the Couns tefs of Holland, and how: at leaft.a whole Clu- iter sof Eggs. in a Hen: are: fecundated. by one Coition of the Male. 5. This givesa new light, _ as it were, to the firft Prophecy concerning the — oy eae ‘os Meffiah,
Mifcellanea Curiofa. 147
Meffiab, that the Seed of the Woman fhall bruife the Head of the Serpent, all the reft of Mankind being thus moft properly and truly the Seed of the Man. 6. The Analogy I have already men- tioned, which we may rationally fuppofe be- tween the manner of the propagation of Plants and Animals, does likewife make this probable. Every Herb and Tree bears. its Seed after its kind ;. which Seed is nothing elfe but a litrle Plant of the fame kind, which being thrown in- to the Earth, as into its Urerus, {preads forth its Roots, and receives its Nourifhment, but has its: form within its felf, and we may rationally con- jecture fomce fuch Analogy in the Propagation of Animals. | 3 + The third Particular which later Difcoveries make probable, is, that Animals cannot be for- med of thefé Animalcula without the Ova in fwminis, which are neceflary for fupplying of them with proper Nutriment: And this, thefe Confiderations fem to evince. 1. It is proba- ble that an Animalcle cannot. come forward, if it do not fall into a proper Nidus. ‘This we {ee is the Cicatricula in Eggs; and tho’ a Million of _ them fhould fall into an Egg, none of them would come forward, but what were in the Center of the Cicatricula; and perhaps the Ni- . dus neceflary for their formation is fo propor- tion’d to their bulk, that it can hardly. contain more than one Azimalcle ; and this may be the _ reafon why there are fo few Monfters. This we fee is abfolutely neceflary in Oviparis ; and the only: difference which feems to be between them and the Vivipara, in this matter, is in this, that in the latter the Ova are properly no- thing more but the Cicatricula, with its Collie guamentum, fo that the Fetus muft {pread forth fer a : “L 2 fe
148 Maifcellanea Curiofa. its Roots into the Urerus to receive its nourifh-* ment; but the Eggsin Oviparis may be proper-— lyterny’d an Urerus, in relation to the Fetus 5. for they contain not only the Cicatricula, with | its Amnion and the Colliquamentum', which is the immediate nourifhment of the Fetus, but alfo the materials which are to be converted in- to that Colliquamentum. ; fo that the Fetus {preads: forth irs Roots no farther than into the White. and Yolk of the Egg, from whence it derives all _ its nourifhment. Now that an Animalcle cannot come forward without fome fuch proper Ni- dus, Mr. Leewenhock will not readily deny ; for if there were nothing needful, but their be- ing thrown into the Uterus, I do not fee why. many hundreds of them fhould not come for- ward at once; for as to what Mr, Leewenhoeck fays, that one of them would be-dwarf and: choak the reft ; this might fall out in procefs of time: But at firft I do not fee why many of them fhould not grow together, whilft {catter’d in fo large a Field (and yet no fuch thing is obferved) if there were not an abfolute necef- fity of ‘a Cicatricula for their growth and thri- ving. Now, 2. That this Cicarricula is not originally in Utero, feems evident from the fre- quent Conceptions which have been found extra Vrerum : Such as the Child which continued Twenty fix Years in the Woman of Tholoufe’s Belly, mention’d Numb. 139. of the Philefi Tranf. And the little Ferus found in the bdomen de St. Mere, together with. the Tefticle torn and full. of clotted Blood, recorded) Numb. 150. both taken out of the Journals des Savans : Such alfo feem :to be the Fetus in the Abdomen of the Woman of Copenbagen, mention’d in the Nouvelles. des Lettres, for Sept. 85. pag» tales
he aa Ba ui he eats.
Pe
-
Mifcellanea Curisfa. 149 the Members of which were eafily to be felr through the Skin of the Belly, and which fhe had carried in her Belly for four Years ; and the fe-
ven Years Gravidation, related by Dr. Cole,
Numb. 172. of the Tranfa&, That thefe two were undoubtedly extra Userum, 1s uncertain, becaufe the laft was not open’d after her death,
and the former may ‘be yet ftill alive. Now
et once the’ necellity of-a-proper. Nidus, for the formation of an Animalcle into, the Ani; mal of its refpective kind ; thefe Obfrvations
make it probable, that the F/fes are the Ovaria
appropriated for this ufe ; for tho the Ani- malcles coming thither in fuch Cafes may feem to be extraordinary, and that. ufually the Im- pregnation is in Utero ; yet it may be collected from hence, that the Cicatricule or Ova to be impregnated, are in Teftébusfemineis ; for if it were not fo, the accidental coming of Animal- cles thither could not make them come fof
ward more than in any other part of the Body,
fince they cannot be formed and nourifhed with- out a proper Nidus. But 3. It is acknowledg’d
by all, that the Fetus -in Urero, for fome con-
fiderable time after Conception, has no connexi- on with the Wom), that it fits wholly loofe to it, and is perfectly a little round Egg with the Fetus in the midft, which fends. forth its Um- bilical Veflels by degrees, and at. laft lays: hold
‘on the Urerus. Now from hence it feems. evi-
dent, that the G#eatriculé; -which’ is the Foun-
tain of the Animaleles-nourifhment, does not fprout from the Urerus, but has its Origin clie- where, and falls in thither as into a ft Soil, from whence it may draw Nutriment for the growth of the Ferus., elfé it cannot. be eafily amagin'd, how it fhould-not have an immediate
, Aaa L, 2 Connexion
150 Maifcellanea Curiofa. Connexion with the Urerus from the time of Conception. If you join all thefé three Confi- derations together, viz. that an Animalcle can- not come forward without a proper Nidus or Cicatricula, that there have been frequent Fetus’s extra Uterum; and that they have no Adhefion to the Urerus, for a confiderable time after Con- ception, they feem to make it evident, that A- nimals cannot be form’d ex Animalculis without the Ova in Femins. To all thefe I fhall fubjoin the Propofal of an Experimentum Crucis, which may feem to determine, whether the Teftes Fw= minee be truly the Ovaria, viz. Open the Abe _ domen of the Females of fome kinds, and cut out thefe Tefticles, and this will determine, whether they be abfolutely neceflary for the formation of Animals. " i by bear} ‘There are fome Difficulties propofed againft this Conjecture, which I think may be eafily re- folved. Some objet the diftance between the Tube ot Cornua Ureriy and the Tefticles ; but to this is oppofed by Swammerdam, and others, the like diftance between the Infundibulum, in Hens and Frogs, and the Ovary; and yet it cannot be denied that the Eggs are tranfmitted thro’ this into the Urerus: And befides R. de Graef, and others, have by repeated Obfervations found that the Cornua Uteri do at certain times after Con- ception, embrace the Teftes on both fides the U- serus. "They obje@in the fecond place the great — difproportion between the pretended Eggs in the Ovary; and the Aperture of the Tuba or Cornua Uteri, the former being a great deal bigger than the latter: But both R- de Graef and Mal- pighius have clear'd that Matter, by making appear, that thefe Bladders in the Ovary are not the Ova, but ferve to form the Glandules
\
Mifcellanea Curiofa. 151 within which the Ova are formed, which break through a {mall Papilla opening in the Glanduley which bears a proportion to the Aperture of the.Tube. They object 3, The difhculty to conceive how thefe, Eggs fhould be impregnated per femen Maris, both becaufe there 1s no. Cen- nexion between. the Tube and the Ovary for its tranfmiflion, and for that Dr. Harvey could ne- ver difcover any thing of it in Usero. As to the laft, Mr. Leewenhocck has cleared that difh- culty, by the, difcovery of innumerable Animale cula Semings:.Maris in Cornubus, Ureri, and thofe living. a.confiderable time after Coition. Numb. 174..0f the Tranfag.'. And as to the former, we may either fuppofe that. there is fuch an Infla- tion of the Tube or Cornua Uteri tempore Coitionts, as. makes them enibrace.the Ovaria, and fuch an approach. of the Uterus and, its Cornua, as that I may eafily*stranfmit the Seed. into the Ovary ; or elfe, that the Ova are impregnated by the _ Animalcles after they defcend into the, Urerus,
and not in the Ovary; the former feems pro- bable for this Reafon, that at leaft a whole Clu- _ fter of Eggs in a Hen wiil be fecundated by one Tread. of: the Cock :) Now this Fecundation feems.to. be in the. Vitellary, and -not in the Uterus, as the Eggs pafs along from day to day ; for it can hardly be. fuppofed that the Animal- cles fhould fubfift fo long, being fcattered loofe- ly in the Uterus, as to wait there for many days for the Fecundation of the Eggs as they pas along. The latter Conjecture has this to ftreng- then it, that the Animalcles are found to live a confiderable time in the Vrerws 5 and that if ‘they fhould impregnate the Ova in the Ovary it felf, the Fwtus would increafe fo faft, that * the Ova could not pafs through the Tube Ureri,
s | L 4 but
ae
152 Mifcellanea Curiofa
but would either burft the Ovary, or fall down
into the Abdomen from the Orifices of the Tube ; and that from hence proceed thofe extraordinary
Conceptions in Abdomine extra Uterum. ‘But, 4. Mr. Leewehceck, Numb. 14.7. of the Tranfa&. to weaken the third Confideration about the Con- ceptions, being like unto an Ovum in the Womb, propofes a Parallel between thefe Animalcules and Infe&ts ; and infinuates, that as the latter caft their Skins, and appear of another Shape, fo the ether which at firft feem like Tadpoles, may caft their outer Skin, and then be round ;and that this may be the occafion of the round Figure of the Concep- tion in the Womb. To this it may be replied, - that according to Mr. Leewenhoeck’s own Senti- ment, the Animalcles cannot come forward, if they do not find the Punéum or proper place for their Nourifhment, to which it feems they muft have fome Adhafion. Now the Conception in Viviparis is not faftned unto the Womb for may days, nor does adhére to any point of it 5 fo that it feems this roundifh Body is not the Ant+ malcle thus chang’d after having ‘caft an outer Skin, but is rather the Cicarricala or little Egg, into which the Animalcle has entred as its pe or place or nourifhment; elfe I do not fee wh
they fhould not be adhering to the Womb from the firft Conception, or why (asI have faid) many hundreds of them are not conceiv'd and formed together, Ge. | Pe ee
Mifcellanea Curiofa. ; 153
at, '> “ aes aS wt ae oe
A fhort Difcourfe concerning Con- - cottion: Read at a Meeting of the Royal Society, May...1699, | by Clopton Havers, mt. D. . Fellow of the Royal Society. —
TT HE manner.in which the Digeltion of B. the Aliment is performed, is a thing not very eafie to be underltood and explained. However, it has not efcap'd the Conjectures of fome Philofophical Men, who having curioufly obferv’d the Phenomena of Nature, and enqui- red into their Caufes, have, amongft other things, endeavour’d to account for this, But their ‘Sentiments about it have been various, and the Hypothefis, by which they have ftudi- ed ‘to ‘explain it, ‘very different, Some have thought the Concoétion of the Food to bea kind of Elixation ; and that the groffer and more folid Parts being, as it were,»boil’d -in the Liquid by the Hear of the Stomach, and the Parts adjacent to it, as the Liver, Spleen, and Omentum, are by along and continued Elixa- ‘tion, firft render’d more tender, and then colli- - Quated, and diffolved into minuter Particles, fo “as to mix more equally with the Fluid, and with that to make one Pulpament, or chylous Mafs. And Hippocrates, tho’ hedoes not plainly call it an Elixation, yet feems to attribute the Conca’ 3 tion of the Food to the Heat of the Stomach, ‘as the Caufe of it, Set. 4. Libro de falubri vittus
| TAationes
154 Mifcellanea Curiofa.. vatione. So where he takes notice of the void- ing of fuch Faces, as appear to be like the. Food that has been eaten ; he adds, Conjtar enim, fane ventriculum, ciberum copiam, ut concoqudts calefacere non poffes . And there ‘ate other. Pafla- -ges in the fame Book, from which we may con- clude, that he fuppos’d the Heat of the’ Stomach — to be the great Caufe of the Digeftion of the Food. , a ag EM There are’ others that make the Stomach it- felf to be the great /Inftrument ‘of Digeftion, but in a different mannér: And they fuppofe it to be perform’d.by. an Attrition, as if the Sto- mach, by thofe repeated Motions, which are the neceflary Effects of Refpiration, when it is diftended by the Aliment, did both rub or grind off fome minuter, Particles from the grofler Parts ; and by continually agitating the Mafs of Food, make thofe Parts, which are not con- tiguous to the Stomach, ftrike one againft ano- ther, and break one another in pieces, until they are all attenuated. It is evident enough, that the fides of the Stomach do in Expiration prefs upon the Contenta, fo as to oblige, at leatt fome Parts of them, every time the Muf- cles of the Abdomen are contracted, to. move and fhift their places. So in Infpiration, when ~ the Diaphragm and Liver prefs upon the upper part of the Stomach, the Aliment muft be mo-— ved again. So that by thefe reciprocal Motions, that} part cf the Food which is contiguous to the Stomach, and moves ina Line parallel te it, muft rub againft it; and all the other Parts be-— ing moved by fuch a Compreffion, as gives them — a different Tendency, it is certain they muft be continually ftriking one againft another. And — for Bread, and fuch things as are made of bad ° chery cay wate ascii that —
——— Mifcellanea Curiofa. 155 that will be foftned and diffolv’d with any, » common Liquid, that Agitation of the Stomach which moves them in Refpiration, might feem - fufficient to break and diffolve them, when they are fuficiently moiften’d with a Fluid. Yet this cannot be thought enough to break and digeft -Flefh-meat, Fruits, or any other thing that will “not be foftned and diffolv’d in Water, or fome fuch Liquid: But although this Motion of the Aliment, caufed by Refpiration, does not adtu- ally digeft it, yet it has a great and necefflary Ufe in -Goncoétion, and makes all the grofler Parts, as they are attenuated, mix equally with- the Fluid. ~ ! | bi
- Some think that the Bilious Juice; others, that the Spirits are chiefly concern’d in this Affair. Galen, in his Book de Neutralibus Facultatibus, makes it to be the Effedt, not of one, but of {e- veral Caufes ; as 2 pituitous Juice in the Stomach, | the Bile, @&c. which appears from what he has faid, and the Tranflator thus render’d: ‘ Verum © quanto ii (cibi) gui manfi funt, it, qui inbafe- “runt, magis funt alterati 5 tanto etiam his magk “tig gui devorati funt. Siquidem incomparalilu © erit horum alterationis exceffus, fi que in ven- © tre eft Pituita © Bilis, & Spiritus, GS Calory 3 © tota Ventris fubftantia, eftimenture : _ Some there are that will have the Food to be diffolv’d by a Menftruum, which is fupply’d ‘from the Glands of the Stomach, or fome other way: But thofe that do fo far agree in the Ge- neral, as to think Concodtion is perform’d by a ‘Diffolvent, do differ in their Notions of the Nature of the Menftruum: For there are fome that fuppofe it to bean Acid, which does erode the grofier parts of the Food, and diffolves them . in the fame manner as Vinegar, Spirit of Vi-
Selig : x Sais ABET, vl trio,
ales
156 Mifceilanea Curiofa.. triol, or any fuch-like Acid, will ‘diffolve even fo folid a Body as Iron. And it cannot be de- nyd, but that Oil of Vitriol will diffolve Flefh- meat, and reduce it to a Pulp ; bur it isnot to be fuppos’d, at the Fibres of the Stomach can admit any fuch ftrong and corroding Acid, without fomething to correc it, but it muft -be injur’d in its Tone, and labour under great and extraordinary Pains. Neither does fuch'a Men- ftruum, tho’ it will digeft fome things, feem ca- pable of diffolving fo great a Variety of Things as we eat, efpecially when a great many of them are of a contrary Nature. Some will have the Menftruum to be a xitro-aerius Spirit, that is, quick, and very penetrating, and included in its proper Vehicle ; which, being in itsown Nature apt to penetrate the Mafs of the Aliment, does diffufe it felf through the Whole, and break- ing the Vinculum of the more folid Parts, does diffolve their Compages. By others, it is _ thought to be fome faline Juice in the Sto- mach, by which the Parts of the Aliment are divided and diffolved, and thofe which are fit for Nourifhment, are volatiliz’d. sh) ee Te _ Laftly, There are fome others who reject the Opinions I have already mention’d, and fup- pofe the Digeftion of the Food to be perform’d by the Benefit of a Ferment ; which, when it is mixed with the Aliment, excites in the Mafs an inteftine motion ; and the different and con- trary motions and tendency of the Parts, making fome kind of Collifion, gradually break off Par- ticles from the groffer, and more folid Parts, till they are fo attenuated as tobe apt to mix more equallly with the Fluid, and with them ‘to make one foft or chylous Subftance. But’ yet there is not amongft them ‘an abi
| : 5 i | ent,
MifcellaneaCuriofa. 57 fent, either about the Nature of this Ferment, : or the manner how it is fupply’d. For firft, fome think it to be the Remains of the Food that was lait digefted; which having lain fome time in the Stomach, after the reft is carried down into the Inteftines, contraéts an Acid, or. fome other Quality, ‘and is fo alter’d, as to par- take of the Nature of a Leaven. And this Lea- ven, being a part of the Food, which has been already digefted, is fo foft and liquid as to be capable of mixing with the Aliment; which is next taken into the Stomach ; and. being agi- tated with it by the repeated Preffures of the Diaphragm, Liver, and Abdominal Mutcles ups onthe Stomach in Refpiration, does diffufe it felf through the whole MafS ; and keing mixed with it, like Leaven, or Yeft added to new Wort, ©c. puts it into a State of Fermenta- tion ; and by this Fermentation, or the Ex- panfion of the Ferment, and the more tenuious Parts, which are firft put into motien by it, thofe which are more folid, and with which they are intermixed, are rent, and divided, and fo attenuated, as to become a foft and pulpous matter. And altho the greateft part of the Food, that is thus broken and concotted, is by the Contragtion of the Fibres of the Stomach prefs’d into the Duodenum ; yet they do not contract themfelves fo as to force out all the A: diment, but leave between the Ruge or Folds, on the infide of the Stomach, a fufficient Quantity to be a Leaven to the next.Meal ;,.and fo from time _ Some havea Notion, That. this Ferment, or Principle of Fermentation, is in the Aliment ir felf ; which being a Congeries of Matter, con- fifting of various Parts of a different Nature, WA tS
158 Maifcellanea Curiofa is no fooner enclofed in the Stomach, and dige- {ted in the Heat of that, and the adjacent Parts, but the more fpirituous and fubtil Particles are put into mation both from that Warmth, and — the difference of theit Natures, and enter upon a Fermentation. And fo by their inteftine Commotion , and the Violence they offer to thofe Parts which oppofe the tendency of any of them, they break and diffolve what is more folid. oo Fea _ Again :* Some fuppofe, that this Ferment is fupply’d from the Glands of the Stomach. And Laftly, Others, and perhaps with much better Reafon, contend for the Saliva, and make that to be the Ferment, which ferves principally for the Digeftion of the Food ; which in Mafti-. cation being mix’d with our Aliment, is with that carried down into the Stomach, where the . Parts of it being put into motion by a kindly and agreeable Heat, they do ferment with, and exagitate firft thofe Parts of the Food which are moft apt to ferment with it, and then both con- {pire to break and diffolve the grofler and more | {tubborn Parts. And Galen, in the Book Ihave’ beforeemention’d, plainly allows that the Saliva is concern’d in the bufinefs of Concoétion, tho’ he fuppofes the Alteration, whichis produc’d by this Juice, to be made in the Mouth, as appears from thefe Words: Que (alteratio) in ore agitur mutat quidem id (nutrimentum) in alteram [peciem manifefte, non tamen ad perfettionem tranfmutat — Qui manfi funt cibi primum quidem bac Pituita (oris ) imbuunter, & cum ea mifcentr———= ‘ ‘Ttaque majorem mutationem confecuti funt, quam iy qui in vacuis dentinm intervallis fuere im- patie Misty i 1a ad ae id 30 HS ; a a
Now —
_Mifcellanea Curiofa. 159
Now I have given this fhort Account of the various Opinions of fome Ingenious Men, con- cerning the manner how Conco¢tion is. per- form’d; I come now to propofe my own Hy- pothefis, by which I fhall endeavour, to ex-
plain it.
In order to the more eafie and effetual Di- geftion of the Food, Nature has appointed fome Parts for the, breaking. our Aliment, and re- ducing whatever is grofs into {maller Parts, be- fore it is put upon Digeftion: Others to fup- ply the Ferment, by which it is to be diflolv’d and concoéted, and which, before it comes to be included in the Stomach, does moiften, and- make it more foft, that it may more eafily be penetrated, and broken by thofe Parts which ferve to divide every Morfel into fmaller Pieces, and prevents the Inconvenience and ‘Trouble which would arife from the Nourifhment ftick- ing about or between them, when it is dry or MUCOUS ye} riclic-od wy oy ,
_ For the breaking of that part of our Food, which is not liquid, Nature. has furaifh’d us with Teeth, and thofe of two forts: For fome are ordain’d to divide and break off {maller Morfels from a larger Mafs; others are made for the grinding thofe Morfels into much {mal- der parts.. Ihe ‘Teeth, which ferve to break off Pieces of a convenient. Magnitude from a larger. Mafs, are of two forts, accommodated to the: Nature of the Subftance which we eat. --Thefe.are the Incifores, and the Dentes Canini. If, the Subftance, which we have to eat, be not hard;.,.byt more eafily penetrated and divided, then the Ineifores, are.capable.of making an Im-. preflionupon, it; and fxd firmly enough in the emer . Jaws
iB ade, NSPS it OL Se ac
~
‘160 = Mifcellanea Curiofa. — Jaws to break off that part which they take hold of. But if ic be more folid, and not eafi- ly penetrated, nor any Piece without difficulty to be feparated from that Body, whereof it is a part ; then we apply the Dentes Canini, or Eye- ‘Teeth, to it, which are not fpread, nor have. fuch an edge as the Incifores, but are fharp and pointed like an Awl, and fo do more readily penetrate a Subftance that is hard, and which the Incifores can fcarcely make any Impreffion upon. And as the Parts of a more folid Body are commonly with more dyfficulty feparated, and there muft be a greater ftrefs put upon thofe Teeth which pull it’ into pieces ; fo thefe ‘Teeth are much more firmly fixed in the Jaws than the Incifores, tho’ they have but one fingle Root. Befides, the Pofition of all thefe Teeth is accommodated to their ufe, as being planted oppofite to the Apperture of the Mouth; fo that they may be conveniently apply’d to the Subftance which we have to eat, before itis bro- ken, and when it is too large to be admitted within the: Maat) 20 ahi? AS Tie eae The Teeth which do by a Compreflien and Attritition reduce the little Moriels: to fmaller Parts, are from the manner in which they break the Aliment, called Dentes Molares, becaule they do, like fo many Mill-ftones, grind the Food between them. And that they might be renderd fit for this purpofe, they are made broad at that Extremity, which’ ftands’ out’ of the Gums, by which means they retain fome Quantity of the Food between them every time the lower Jaw is pulled up and fore’d againft the ‘Maxilla fuperior. And\as they are broad, fo they are formed with Inequalities and Protube-. rances ; and by the motion of thé lower Jaw, . i from
SES cK by
ae ee ial one Mae a Be ve ea att
Mifcellanea Curiofa. = 161 from one fide towards the ether, they grind what they have between them into pieces. The Pofition of thefe ‘Teeth too is as conve- ninent as that-of the Incifores, and the Den- tes Canini : For being defign’d to. break thofe pieces of our-folid Food, which are taken in- to the: Mouth, and thefe pieces, when they are comprefs'd, and movd e the Dentes Mo- dares, being apt to fly out of the Mouth, if there were no Contrivance to prevent it, they are placed beyond the Aperture of the Mouth, and oppofite to the: Cheeks, which keep ‘the Food: within that Cavity, and not only. fo, but prefs it in between the Dentes Molares on one fide, as the “Tongue does on the other, until they have fufficiently broken and divi- i dedgec yd. ths! 2 .
At the fame time, whilft the Dentes Molares are breaking the Food, there flows into the Mouth a Salival Juice, which mixes with it, and not only ferves to moiften it, and to render it more apt and eafie to be divided, but feems _ to be the Ferment, by the Benefit of which the Food is diflolved and digefted. And therefore it is intimately mixed with it, by the Teeth _ agitating or ftirring them together in Matti- cation. | :
- This Liquor, which we commonly call .the Saliva, or Spittle, feems to be a Compofi- tion made of two feveral Juices, very diffe- rent in their Nature : And therefore the {e- veral Parts of it are {€parated by their pros _ per Glands, and Nature has planted no fewer
than four Pair about the Mouth, which fup- ply the Juices that make the Saliva 3 to wit the Parotides, and. the Glanduleé Nuckiane,the
Se. M Glandulz
bleh teh SSE GE ae ENS hore
Ree gee
162 Mifcellanea Curiofa:. Glandule Masxillares interna, and Sublinguales. Whereas if the Saliva were but one more fimple — Liqucr, a Jefs number of Glands might have. been fufficient. At leaft there appears no Rea- fon why one of every Pair fhould difembogue it- — felf into the Mouth fo very near to. the’ Orifice, by which a Gland of fome other Pair throws in its Juice ; and they are not rather all planted: at more equal diftances from one another, fo to flow in upon every part of the Aliment at the fame time. , do hone Bataleon
Not that I fuppofe, as there are four Pair of falivatory Glands,.fo there are four forts of Juices fupply’d from them, to make the Sali- _ va; but, as I hinted before, that there are only two different Juices that conftitute it. And thefe are not only fufficient, but more — proper to’ excite and fecure that Fermenta- tion, which is neceflary to Concodtion. For we find that moft of thofe Fermentations, which arife upon Mixtures made for Experi- ments, are produced from the mixture of two things ; and it is not fo eafie to find out three or four fuch. Liquors of a different Nature, as . will, upon the mixtion’ of them all, preduce a Fermentation,” and from the omiflion of any, one of them difcover no Difcord or Difpofi- tion to ferment: Befides, it is certain that two do better fecure the End, which Nature defigns. For, it there were three or four diferent Juices, of which the Salioa‘naturally confifts, thefe muft all have their proper Qua< lities pyeferved to them. or elfe the Fermen- tation, which fhould arife between them, will not. neceflarily follow upon their mixture ; and it is certain, that there would ‘be more
el Danger,
*;
— Mifeellanea Curiofa. 162 Danger, that one of three or four fhould be deprived of its Natural Quality, than one of aes So aree | ” What Nature thefe two Juices are of, I do not pretend pofitively to determine ; but fo far as I have been able to make my Conje- Gtures about it from Experiments, [*do think one of them to be an acid Juice; the other an oleaginous Liquor, fomething like Oil of Tur- ail.” ‘For amongft the many Experiments ‘have made, there was no one that gave. me fo muth Satisfaction, as thar which I made - with Oil of Turpentine, and Oil of Vitriol, though'I try’d feveral’ other things, that will produce a Fermentation upon their Mixture. And it was for this Reafow, thac I made the txperiment with Oil of Turpentine and the ee ‘1 ‘took ‘a. piece of raw Flefh, and having cut it into pieces, but: much larger than what our more folid Food is reduc’d to by due Mattica- tion, I mixd fome Crums of Bread with it, then I pour'd in the Oil of Turpentine ‘to them, and upon that the Oil of Vitriol ; and having’ fhak’d them together, I digefted them about four Hours in Balneo Marie, and then fhaking them again in the Glafs, I found the Meat diffolv’d, and they all became a thickifh Pulp. I could not but take notice, that Oil of Camphire (though it does not orherwife feem much different in its Nature from Oi! of Turpentine) and Oilof Vitriol, which upon mix- ture will produce an Effervefcence as well as the Oil of Turpentine and Oil of Vitriol, yet did not touch the Meat, upon which I poured them, fo as in the leaft to diffolve them. I eee 2 -—- €annot
5
Co LEENA Se RAE ane ee 1a a
164 Mifcellanea Curiofas cannot deny but that an Acid, and a Solu- tion of Salt of Tartar, did diffolve fome part of the Flefh-meat, which I mix’d them with, © ‘but yet neither fo foon, nor fo perfeétly asthe . two forementioned Oils. And I do the ra- ther think one of thofe Juices, which confti- tute the Saliva, to be of the Nature of Oil of Turpentine, than of a fix’d Salt, becaufe it will correct and temper even Oil of Vitriol, -fo as to render it more tolerable to the Fibres of the Stomach. Nort, that I fuppofe the acid part of the Saliva to come near to thé Acidity. of Oil of Vitriol. For though, when they are mix’d, they will make a Liquor that may not be injurious to the Stomach ; yet the acid Juice, if ic were fo corrofive as Oil of Vitriol, would . certainly be injurious and ‘painful to the Saliva- tory Duéts, which convey it to the. Mouth before it is mix’d with the »olcaginous, Liquor. But I only fay it is an Acid, and in fome de- gree approaches to the Nature of that Oil. © And Nature, which. can much better adapt _fe> — veral Caufes for the Produétion of fuch an Ef- fe&t than Art, may attain her End by a more — temperate Acid; though, at the fame time, we may be able to make fome probable and true — ConjeGtures about the Nature of thofe Caufes — from Experiments. ae ae Te being moft reafonable to fuppofe, that — there are but two forts of Juices, of a different — Quality, that make the Saliva, 1 do ‘conceive, — thac four of the eight Salivatory Glands, or — two Pair of the four, do fupply one. of thefe Juices, and the other four Glands the other. — And this feems to be a very good Reafon, why — they are fo planted, and the Orifice of their —
Mouth; very ‘near to the Orifice, by which
the- Jaice ‘of a ‘different Nature is tranfmitted from another, fo that’ they mutt receflarily meet and mix together. Thus the Glandule ‘Nuckiane; and Parotides, throw in two diffe _ rent ‘Juices’ by Orifices, which open into: the Mouth very near to one ‘another; and the Glandula''Maxillarés’ interné, and Sublinguales, do below fupply the fame ‘kind of Juices by Orifices; that open fo near to‘one another as to fecure the mixture ofthe two different
Juices. |
->Thefe Glands, I fay, do between them af- ford two divers forts of Liquors, of fuch a ‘Nature a3 are apt to ferment upon their firft Mixture, but perhaps more confiderably when they come to be digefted by the Heat of the . Stomach. So that the Colludtation, or Fer- mentation, which attenuates and concoéts the Food in the Stomach,’ does not ordinarily a- rife. between the Aliment and the Saliva, but between the feveral Parts of the Saliva it felf. And indeed, if the Saliva did not confift of two Juices, whofe Nature is in fuch a manner different, as to render them apt to ferment upon their mixture, it would be very hard to conceive how it fhould fo readily and indiffe. rently ferve for the Digeftion. of all Eatables ; how it fhould ferment with, and diffolve fo
reat a variety of Things, not only of a dif- erent, but of a contrary Nature; how it fhould ferment with Acids as well as Alkalies, : digeft things that ‘are cold, as: well’as ‘hot’ or tempe- rate fome things that’ are “fale, “others that Ae 8 1 | M ? f are
be ee
166 Mifcellanea Curiofa.
are infipid, bitter and fweet, mucilaginous, oily, &c. But if we fuppofe, that the Fermentation, which ferves for the Digeftion of the Food, arifes from a peculiar difference in the Nature of two Juices, which conftitute the Saliva, it will be eafie to give a rational Account of our Concoftion of innumerable things of a different Nature. And this feems to be as effectual, and a more certain way to attenuate and dif- folve the groffer Parts of our Food, than if the Fermentation were made only between the Sali- va and the Aliment: Befides, the Saliva feems - to difcover a Fermentation upon the mixture of its ‘conftitvent Juices, even at thofe times when we do not actually eat; for it is al- ways attended with Bubbies, and a Froth, when ic has not been at all agitated in the Mouth, and many of thofé Bubbles will remain for fome confiderable time after we have fpit it out. . : Nature therefore having appointed the Sa- liva for the digeftion of the Food, has taken _ care that it fhall be thrown in ‘upon the Ali- ment on every fide. Thus the Glandule Nuc kiana, and the Parotides, fupply their Juices to that part of the Food, which lies.on the outfide of the Gums, between the Cheeks and the Teeth, and the Glandula Maxilares intere na, and Sublinguales, do beftow their . Liquor upon the Meat, which is within the. Teeth and Gums. Neither has fhe had a Regard © only to that Supply, which is due to all the parts of our Food, but likewifé to the mix- ture of the two different Juices of the Saliva, — which is neceflary to its Fermentation. And therefore, as I have already obferv’d, the : ; rinces
dy
Dik, CA, eee OP te ee eee Vee a 4 a ae tee ai " He
rifices of. ihe Dué@s,. which, belong to one fort of. Glands, are placed near the ‘Aperture of a Du&, which conveys a Juice from one of the other Glands. So the Duéts of the Glandulz Nuckiand, and the Du&us Stenoniani; do on each fide open. into the Mouth, near: one. another ; and the falivatory Duéts of the Glandula Subline guales, and the Maxiflares interne, though they have diftin& Orifices, empty themfelves under the fame Papille; and the Juices, which are fup- ply'd by them, meet there, and flow into the Mouth together.
The feveral Parts of the Saliva ane dit charp’d into the Mouth in fuch a manner as to meet and begin a Fermentation, the Saliva does, partly as it is agitated, with the Food by the Teeth, and fome other parts of the Mouth ; partly by its owa Fluidity, inGiauate it felf into, and mixes with the Food, and not only moiftens and foftens it, but excites the Fermentation, which is to diffolve it, And when. the Aliment is thus mix’d with the Sa/i- Day which - ferves to ferment the whole Mal, it is then to. be convey’d into the Stomach, hhee great digettive Veffel of the Body, where the Fermentation is not only continued, wed im= proved.
The . Nourifhment being: conyey’d into the
: Cavity of the Stomach, is there kept for fome time in) a digeftive Heat, all which time it is under a Fermentation, produc’d by the diffe, rent Parts or Juices of the: Saliva, which are
mix'd with it ; which Fermentation dues fit agitate| the more tenuious or fubtil parts of the; Foad, aod, puts, them into; motion, and fo wih hi sh Fermentation . of its. own, and thofe “M4 -Alimens
atancaGirige. 267
a
in USE AML LN SRE tn 8
168 Mifcellanea Curiofa.
Alimentatry Parts, which it firft communicates a Motion to, improved by the Heat of the Stoe mach, the Saliva muft neceflarily a& upon
the groffler Parts. For the inteftine- Motion,
which is excited in the Mafs, does not give the Particles, which are fermented, the fame Ten- dency, but what 4s fo various and confus’d, that they muft inevitably ftrike not only one a- gainft another, but againft thofe which are more grofs, fo as to attenuate them, fometimes
by a Collifion, which ftrikes off fmaller Par-.
ticles from the larger Parts; fometimes by a Compreffion, when the Particles which are in Motion, happen to ftrike dire&tly againft any’
groffer Part, om every fide of it, fometimes’ by a kind of Explofion. For without doubr’
the Salivg, which is fluid, infinuates it felf in-
to the Interftices of the more crafs Parts of
the Aliment, and whatever is agitated and ex-'
panded in thofe Interftices, requiring a larger
fpace for the Freedom of its Motion, and of-
fering a Violence to every thing that oppofes’ its "Tendency, will, like Gun-powder included in.a Shell, force its way out, and tear to pieces that Matter, which does endeavour to con- fine it. Ae OETA
Thus the grofler Parts are broken and di-
vided, until they are at laft fo far attenua-
ted as to mix more equally with the’ Fluid, :
and with them to make one Pulp or Chylous’ Mafs. And although I do not apprehend how the Stomach fhould by its reciprocal Mo-
tions in Infpiration and Expiration, ‘be able to
break and attenuate any Matter, that will ‘not be foftned and diffolved by Agitation in a ether 3 yet it is certain that thefe Motions, caufed' by
i Se me
Mifcellanea Curiofa. yb9 the Diaphragm and Abdominal Mufcles.in: Re. fpiration, do make thofe Parts, which are bro-. ken off, as they are diffolv’d, mix intimately: with the more Liquid ; as the Meat which «I digefted with Oil of Turpentine, and Oil of Vitriol, did by Agitation mix more equally with the Oils, and became a Pulpament.
As the Juices, which conftitute the Saliva, do ferment upon their mixture, fo it is probable, that from their Mixture and Fermentation there refults fuch a Tertium quid, as is apt to fer- ment with the Bile. And therefore, when the Aliment has been under the Fermentation, ex- cited by the Saliva, a fufficient time, it is then thrown into the Duodenum, where it-meets with the bilious Juice, which flows into that Inteftine from the Liver, from which a new Fermenta- tion feems to begin; and the Commotion of the Parts of the Aliment being ftill continued, does -earry on the Bufinefs of Digeftion until the Food is perfectly concocted : Though it is probable, that this new Fermentation ferves not only for the more perfect Digeftion of the Food, but like- wife for the Separation of the Chyle from the Selene Page Neither do I by a random Guefs, and an- ungrounded Conjecture, fuppofe that from the Mixture and Fermentation of the two Juices, which conftirute the Saliva, there refults a ' Matter, which is apt to ferment with the Bible. But to me the Notion feem’d to be confirmed by an Experiment that I made. For confidering with my. felf, that the Bile is generally allowd to have much of a fapo- nary Nature, I made a Solution of Soap in fair ‘Water, and mix’d it with the Oils of Turpentine ee and
Pr arene,
S
170 «©=©Mifceilanea Curiofa. .
and Vitriol firft put together, and from their: Mixture I obfery’d a very eafie and gentle Fer- mentation. which continued for a confiderable’ time, EO) «> ire Ee ee eek ed fiay
a : 5 at i “ a \ (ie 2 z ‘ x. aa 4 7 # bm re J t ae A a ; . 4 PS a a » be oer : ; * 7 > a t \ ’ oF f «, H t a “ : { » ¢ 4 . . ex" § ne 4 . x . 48 : gf $ q * ’ ‘ . ‘ "y ~ 9 <# as a aia 4 * * 7 > ¥ * i i : ie ai! * » 9 ’ “ r 7 Wi , ; BB ata 2 f i by “ mt) * > » ¥ ; ‘ 4 pe | i o3"5'F , f - * , rt te o “e { : 4 baa Ta0tES , i or y Oe ee a” . ea ; A : “3 ES oe | ' pa ; ; ‘ } t gig Lk Z - sole SOR7 26 J . - é . #. 4 i* ‘ i Yoon a ; r $ ee
‘ Be tes P Lane a A ae é a wee fe a é s % iy Si of Pee SS vi 4 iv5ik uf ee 8 oe BF AS ¥ , ’ vs . 0.89 ye é ‘ , » tj } Se alle ith 7k : Orem | “ . ' . ‘ ‘ ' j ~ » , « 7 n + “~ 4 : <3 ; i bi § ) : + ' i Pee ih ‘ ‘ { : i fa ht m J , Yi pa ee Be Be ‘ » 9 > * eed | i * py ys Be r' } i # r Hprerer ay le Lise fie VO bse SER Tare 2 es ba Od {aT . ne bey t ° ; Cae aad - ¥ “ usr > : « 4 is Pn a | ri’ Li - wetr 4P ti. ’ ing AV GIN Stas dowd WH { bat Patt a Bits PBs Bia? i , we \
— Mifeellanea Curiofa. aa
A Difcourfe concerning fome Influ- ence of Refpiration on the Mo- tion of the Heart, bitherto. un- ee one - ByJ. Drake, M.D,
YHO’ divers accurate Treatifes of the |
BO Heart, and its A&tion, have been Writ ten by Learned Men of feveral Nations, efper dally by two of our own Country; the Great Dr. Harvey, to whofe happy Sagacity this Na- tion owes the Glory of the Invention of the Circulation of the Blood ; and the incompara~ ble Dr. Lower , to whom we are beholden fora compleat Difplay of the Mechanical Strue. ure of the Heart, and a moft ingenious Ra- tionale of its. AGtion. Yet there remain feve- ral Doubts and Difficulties about it (in my Opinion ) - not ‘fuffciently accounted - for; to= wards the refolving fome of which, I fhall of- fer what my own Thoughts have fuggelted to me, and leave it to the Confidetation of the a at ee ~The Learned Dr: Lower ( whofé accurate Piece on this Argument will ‘infure ‘his’ Repu- ‘tation fo long as Phyfical Knowledge’ fhal! laft in efteem) has fo well accounted for the S)- ftole, or Contraétion of the Heart, from the Mechanical ‘Structure. of ‘it, that he feems al- molt to have extiauited the Subjett ; and had ONGkTHIG S| "
OP eo ere eed og
ie “j a
172 Mifcellariea Curiofa. he been as happy in difcovering the true caufe of the Diaftole, he had’ left Tittle room’ for the Induftry and Sagacity of others about this Vifes 3HWO\ QcAtaINOD Sno RL But having. judicioufly -and {elidly explain‘d the Syftole, he contents himfelf to afcribe the Dia- frole to @ motion .of! Reffitution, which! account gives me no Satisfation : Becaufe the Sy/tole be- ing the proper, and (as himfelf confefles) the
only mofion of the Heart, a State of. Contrattion
1"
feems to be the natural State, and confequently without External Viclence, it fhou'd have no
Diaftole at all.
This will appear more plain, if we confider
the Circumftances of it, and its Motion, as a Mufcle, with refpect to other Mutfcles. That Contraction is the proper Action, and State of all Mafcles, is evident from Experience of Fact, as well as Reafon. For, if any Mufcle
be freed from the power of its Amtagonift, it
is immediately contratted, and is not by any Action of the Will, or Spirits, to be reduced to a State of Dilatation. Thus, if the Mufculi Flexores of any Joint be divided, the Extenfores of that Joint being by that means free’d from the contrary Action of their Antagonifts, that Joint is immediately extended without any
confent of the Will, and in that State it re-
mains; and fo Vice verfa, if the Extenfores be
divided. From whence it is plain, that the Mufcles have no reftitutive Motion, but what —
they derive from the Action of- their Antago-
nifis, by which they are balanc’'d. Thus like-
having, no proper Antagonifti, are always in a
State of Contraction, and fiffer nothing to pafs a , them,
te Se og oe ee ee. wegen Seated
ak 4
we ras uh pk. Re ey Te BER Ae Ye) ae! +
Mifellanca Curiofs. 172
them, but what: is forced through them by the contrary Aétion of fome ftronger Mulcles, which, though not properly to be call’d Antagonifts, yet on all neceflary Occafions perform the Office of fuch.
That the Heart is a Mutcle, farnith’d and inftruéted for Motion like other Mufcles, . is Cin my ‘Opinion at Jeaft) demonttrated . 4 yond Contradigtion | by Dr. Lower and others. And, as it is a Solitary Mufcle without any pro- er Antagonift, and not directly under the pow- a of the Will, nor exercifing Voluntary Mo- tion, it approaches neareft to the’ Sphintter kind; which only ‘has thefe Conditions in common with. it, But in conftant and regular Al-« ternations of ContraGtion and Dilatation, it dif- ah exceedingly from all the Mutcles of the
y-
.. This reciprocal Aftus of the Heart has. gi- ven the Learned abundance of trouble ; who, finding: nothing peculiar in the Structure, which fhou’d neceflarily occafion it, nor any Anta gonift, whofe re-a€tion fhould produce it, have oi extreamly perplex'd t to find out’ the caufe Or it.
But pafling over the various Opinions of Au- ; hors, to avoid being tedious, I fhall take notice here only of the very Learned Dr. Lower’s, in whofe Account of the Sy/tole, however folid and ingenious, I obferve fomething deficient, and whofe Hypothefis of the Diaftole I think to be pre- carious and falfe. °
‘This Excellent Author, - fvinet ‘by~ found , ‘Arguments drawn from ‘the Stru@ure and ~Mechanifm of the Heart, eftablifh’d the Cer- si of its ia aa Marion refts fatisfied,
with
OR ON, 5S Pe ee ee pint, me ‘i A A Pa ie 5 eens
174 Mifellaned’Cuntofa.
out taking notice of any Afliftance, that the Heart receives from any other Part, except from the Brain, by the means of the eight pair of Nenves. Ry hs ait aa ... 4. The Accurate Borellus, in his Qeco- Part 2de — nomig Animalis 5. computes . the Mo-
Prop. 87+" ye Power oF the Machine of the |
Bnei Heart to be equal to, or to farmount that of a Weight of 3000/. The Obftacles to the ‘Motion of the Blood thro? the Arteries he efteems equivalent ‘to 180,000 /.. which is 60
dimes as. much as he rates the Force of the
Heart at. Then dedu@ing 45,000/. for the —
adventitious Help of the Mufcular Elaftickh Coat of the Arteries, he leaves the Heart with a Force . .. of 3,000 J. to overcome a refiftance Prop. 76 of 135,000 J. thatis, ~ with 1, to re- _move.45. et A ages,
_ This ftupendous Effet he contents himfelf
to afcribe to the Energy of Percuffion. But, had
he proceeded in his Calculatin to the Veins,
which he allows to contain conftantly a quantity of Blood, quadruple to the Contents of the Ar- teries, and to which this Energy of Percuffion does either not reach at all, or but very languidly, he might probably have feen a necefiity for fome other Expedient to remove fo infuperable a Dif- erik Peo, SE
But.not to infitt rigoroufly on the Exa@nefs |
of this; Calculation, (though the.great Abilities
of ‘the Author in this way, and his Ingenuity |
and Modefty, are a fufficient Warrant for the Accuracy of his Computations, and the Fidelity of his Accounts). we may. allow a much — greater Deduction, than would be juftifiable, — without leffening the Difficulty. But this Ac- —
: — count
“i
Mifcellanea Curiofa. 175 count I have taken notice of purely for the fake of the Calculation, which may be of ufé in the Sequel ; the account it elf being in other refpects more defective than Dr. Lowéi’s, to which we - will return. . geiet bie (iw . The Doétor, notwithftanding ‘his great Saga- city, appears (to me) to have overlook’d fome- thing of very great moment, and importance in
the explication of the Aétion of the Heart, For, tho’ it fhould be granted, ‘that the Mujfcu- lar Fibres: of the Heart acted by the Nerves, are the immediate Inftruments of its’ Confri@icn or Sjftole 5 yet it muft not be denied, that the Fx tercoftal Mufcles and Diaphragm are’ of great {ere vice. to aid and facilitate this Contraction, by “opening a Paflage for the Blood through ‘the Lungs, which denied: would ibe an davincible patel ei rlsid AEE OG) Ther Fe Neither do they promote it that way only, The manner how they farther afift the Heart in its Contraction, will appear manifeftly, if we confider the different Polture, Situation, and Capacity of the Blood-Vefléls of the Lungs ‘in the feveral times of Elevation and Depreffion of the Coffe. . Meant eh U1: | - The Pulmonary Artery rifes from the ight Ventricle of the Heart, and runs in one Trunk, ‘ull it comes to the Afpera Arteria, where it is divided, and fends :a Branch along with each Divilion of the Afpera Arteria, accordins to al the minuteft Subdivifions, «of which Gt. js likewife fubdivided 5 accompanying all the - ‘Bronebi, in their whole progrefs through the Lungs. | ven: The Pulmonary Vein, which empties it {elf amo the Left Ventricle of the Heart, {preads Ww | it
176 Mifcellanea Curiofa. it felf on the Afpera Arteria and Bronchi, in the fame manner that the Artery does: ) ME ie _. The neceffary confequence of this Difpofition is, that this Artery and Vein being co-extended witB, and faften’d to the Bronchi, muft needs fufler fuch alteration of Suterficial Dimenfions, as the Bronch: do in the Elevation or Depreffion of the Coffe. | Re ae ge oe cae tee _ While the Ribs’ are in a State of Depreffon (whether before Commerce with the External Air or afcer) the Annular Cartilages of the Bron- chi {hrink one into another, and by that means their Dimenfions. are exceedingly contracted. In conformity to this condition of the Bronchi, the Pulmonary Artery and Vein muft likewife, ei- ther by means of their Mufcular Coats, con- tract themfelves to the fame Dimenfions, or lye : Folds or Corrugations, which is lefs. proba- e Che oe On the other hand, when the Ribs-are ele- vated, and the Diaphragm bears downward, the Air rufhing into the Lungs, fhoots out the Car- tilaginous Rings, and divaricates the Branches of the Trachea, and by them extends and divaricates the feveral Divifions of the Pulmonary Artery and Veins, and thereby lengthens and enlarges their Cavities. ata Be erie ae: _ This enlargement of their Cavities is very confiderable, not only upon the fcore of the addition, which they receive in length there- by, but alfo upon the account of their Divari- cation. For whereas, when the Ribs are de- prefs’d, and the Lungs fubfide, the Blood-Vef- fels are not only contracted, (as I have alrea- dy obferv’d) but their Branches, which are exceeding numerous, approach one a
| i Kuen }
Mifcellanea Cuviofa. = 177 and lie in juxta-pafition, by which their Cavities _ are very much comprefs'd and ftreighten’d: When
the Ribs are elevated, and the Lungs turgid with
Air, not only the Fibres, by which their Coats ~ in the oppofite ftate were contracted, are exten-
ded ; but thofe innumerable Veffels, which ly-
‘ing before in lines almoft parallel upon one
another, comprefs’d one onother, making an
acute Angle at their Jundtures, are divaricated and feparated from each other, and make an obtufe, whereby their Channels are wide- ned. ae : | . Thus a paffage is open’d to the Blood, from the Right Ventricle of the Heart to the Leff, | through the Lungs, to whiclt ic could not other- wife pafs 3 and the *’déppofition, which the
Blood contain’d in” that Ventricle, muft other-
wife neceflarily have made to its Conftriction, is taken‘ off, and the Syjtole thereby facilita-
1 ee 3 ~ Nor is that all. For-the Diaffole being
causd (as I fhall in the Sequel fhew) by the force of the Blood rufhing into the Ventricles, this Ampliation and Extenfion of the Pulso- - nary Artery is a fort of Check or Counterpoife to it, and prevents an endeavour towards two contrary Actions at once, which muft necef- farily fruftrate both. For the Heart being a ‘Springy, Compreffible Body, whofe proper Action,
“which is Contraction, depends on the influx of certain Fluids into its Fibers , or Subftance ; and containing’ befides a Fluid in its. Venerf- cles, or great Cavities, in one of which is the
“Mouth: of this Artery, the action of this Vef- ~ fel muft in great meafure refemble that of a
Syringe, whole extremity is immersd in Wa-_
Re ter;
hate
178 Mifcellanea Curiofa. ter, the Enlargement or Expanfion of the Cha- nels of the Artery anfwering the drawing of the Embolum, as the conftri€tive motion of the Muf- cle of the Heart does the preffure of the <rmof- phere upon the Surface of the Water, the one making way for the fluid, and the other forcing it to follow, where the refiftance is leaft. In this Senfe we may allow a fort of Attraétion to the Pulmonary-Artery, depending wholly upon the Action of the Intercoftal Mufcles and Diaphragm, which we muft therefore confefs to be very fer- viceable and inftrumental in promoting the Syftole of the Heart. ~ |
But if the Learned Author be deficient in his Account of the Syffole; that is, if he has not obferv’d all the Mechanifn and Contrivance of Nature for the Contraction of the Heart ; much lefs {ufficiently has he accounted for the Dja- ftole, or Dilatation of it, which he afcribes to a motion of Reflitution of the over-{traind Fibres, which yet he confeffes are made for Conftriéion \ only. ’Tis true, he immediately after joins the Influx of the Blood as a concurrent Caufe ; but | from the flight notice that he rakes of it, ’tis plain, that he did not fo much as dream of any great fhare it had in that AGion. His Words arethefe: — :
Quin FB (ut obiter hoc moneam) De Corde, Pag. omnis motus contrattione perficiaturs — 75: & Cordis Fibra ad conftriftionem
folum fallea fint, apparet quoque Cordis motum totum in Sy ftole pofitum effe 5 cum-— que Fibre ultra tonum fuum sn omni conftrittione ejus tendantur, idcirco ubi mixus ifte abfolvitur, mo~ eu quafi reltivutionis Cor iterum relaxatur, © fane- | Suing
# ~ pea
Mifcellanea Curiofa. 1799 guine aVenis influente rurfus diftenditur ; 2 nullo enim cordis motu, nifi tenfionem fuam remittente, & ab irruente fanguine Dialtole gus libratis adeo viribus fuccedit.
I have tranfcrib’d the intire Paragraph, be- caufe it contains his whole Hyporhefis of the Dia- frole, and all the notice that he takes of it through his whole Work. Bur how flender fo- ever this may prove, it is the moit jubftantial that I have any where met with, except a late one of Mr. Cowper, which is properly an Improve- pene of this, and fhall be confider'd in the Se- uel, | i : But if Contraétion be the fole ACtion of © thefe Fibres (as this Great Man confefles it to be) and as indeed it is of all Mu/cular Fibres, I wonder how fo judicious a Writer came to flip into fuch an Abfurdity, as to call their Diftention- (vulgarly but improperly call’d Relaxation) a
» Motion of Reftitution. For from the Nature of
thofe Fibres, and their difpofition in the Strue Gture of the Heart, the natural State of the Heart appears manifeftly to be Tonical, and its Dilatation a State of Violence ; and confequently, the ConftriGtion is the true motion of Reftitutions and the State to which it will /ponzaneoufly re- turn, when the Force is taken off, which is the work of the Intercoftal Mufcles and Dia- phragm. , Thus we are lefr ftill to feek for the true Caufe of the Diaftoley which feems to me to be the main ard moft difficule Phenomenon, re- lating to the Heart and the Circulation of the Blood. But in Mr. Cowper's ingenious Intro- duBion to his Anatomy of Humane Bodies, 1 ) N 2 find
—
180 Mifcellanea Curiofa. e
find the. Share which Dr. Lower hints the Blood to have in that Aétion, further profe- cuted, and improved into the main Inftru-
ment of the Dilatation of the Heart, wherein -
I agree intirely with him. But as to the manner, and reafons of its being fo very in-
ftrumental, I can’t be fo perfectly of his mind. —
The Heart (fays this accurate Anatomift) of
an Animal bears a great Analogy to the Pendu-
lums of thofe Artificial Automata » Clocks and
Watches, whilft its motion u% performed like that
of other Mufcles, the Blood doing the Office of 4 Pondus. |
This Explication , being but a Simile without a diftin€t application to Particulars, is befide fo very fhort, that I can at beft but give a conje€ture
at the meaning ; which if I miftake, I fhall de-
ferve to be excufed, and expect to be better in- form’d. aie: |
_ I fuppofe he means, that the Blood contri- butes in the fame manner to the motion of the Heart, as the Weights do to that of the Pen-
By the Bloods doing the Office of a Ponduty
dulum of a Clock. If fo, the Blood, according 1
to him, muft be the Inftrument of Conftriftion ; and Dilatation muft be the Natural State, of Spontaneous Motion, to which it wou'd, when under no violence, return ; the contrary of
which, I prefume, will appear e’re"I have
done. | But if he means, that the Blood in its reflux, by gravitating on the Aaricles and Ventricles,
dilates and expands ’em, acting therein as a
Counterpoife to its contractions as a Mufcle, I coud with his Defign had not bound him up
te
Mifcellanea Curiofa. 181 to fo narrow a compafs, and that he had given -us an explication at large of fo abftrufe and fo ims portant a Phenomenon: Becaufe the Specifick Gra- vity of the Blood feems to me a caufe by no means alone adequate to the effect, which it is here fuppos'd to produce. 7
For, if the Blood acts only as a weight by meer gravitation, then that part of it only which defcends from the Parts above the Heart can be employ’d in that Action. This at the largeft computation can’t amount to ~ Five pound weight, and muft, according to the computation of Borellus, force a Machine, that is able to overcome a refiftance of 135, o00/. 1 leave every Man to dedu& what he fhall upon examination find reafonably to be deduuéted, and yet fhall reft fecure, that ir is not to be effected in the leaft with fo {mall a Weight. . |
But neither does the Refluent Blood gravi- tate in any fuch proportion, as I have here affignd. For to make a true eftimate of its Gravitation, we muft confider the Circumftan- ces of thegLiquor fuppos'd to gravitate ; in which it very much refembles Water inclos’d in a recurve Tube, of which, if the length of the two Legs be equal, it may be fulpended in the Air full of Water, with the Extremi- ties downwards, without lofing a drop, al- though the Diameter Ok, thofe Legs fhould be ye-. ry unequal, The Cafe of the Arteries and - Veins is pretty near; a parallel.to a Tube, fo filld and inverted. For, if the Arteries and Veins be continued Tubes, (as by -the Micro- {cope they are made to appear) then {up- poling their contents to have no other determi- alone N 3 nation
PNA eee sh aris Nl as Mian nh da!
182 Mifcellanea Curiofa. mination of motion, than their own weight wou’d give them, the contain’d Fluids muft be Coun- terpoifes to each other. For the Veins and Arteries being join’d at the fmaller Extremities, and the larger of both terminating in the fame _ parallel Line, it is impoffible, according to the Laws of Hydroftaticks, that the contents of either fhou’d overbalance other. How far then muft it fall fhort of forcing the natural Power and Refiftance of fo ftronga Mufcle as the Heart, by meer Gravitation ? | Pe
The Blood indeed has a Progreffive Motion through its Veflels, wherein it differs from Wa- ter, in a reéurve Tube, in the Experiment a- * bove-ftated. But, if the natural Gravitation of ~ the Blood contributes nothing to the Dilatation of the Heart, this progreffive Motion will not not be found much more fufficient. For, as this Motion is deriv’d intirely from the Heart’s Con ftriGtion (as all Accounts hitherto derive it ) __cou’d the Blood be fuppos‘d to re-aé& upon it by the Heart, with all the force firft imprefs’d up- on it by the Heart, it would be infufficient, unlefs - we will fuppofe the Force communicited to be fu- periour to the Power Communicant, which is ab- fifd. <. 72 : da - But when the juft and neceflary Deduétions for the Impediments, which the Blood meets — with in its Progrefs through the Veflels, fhall be made, the remaining Force will be found fo exceeding weak, that to prop the Blood through the Veins may be a task alone too great for fo fmall a Power, without charging it with the additional difficulty of forcing the Mufcle of the Heart. | ate a
| Alpbonfus
bi Mifeellanea Curiofa. 183 ‘Alphonfus Borellus, after a great deal of fo-. lemn pains taken to fhew his Care and Exaét- nefs, and to poffefs his Reader of the Truth of
his Calculations, cafts up the force of the
_ Heart, and the Mufcwlar Coat of the Arte-
ries, to be together equal to a weight of
3,750 1. and allots them a Refiftance equal to
~~ >
180, 006 /. to overcome which is 45 to 1: To
make up for a difproportion, by his own con- feffion, incredible to thofe who have: not cone fider’d the Matter as he had done, he flings into the Scale the additional Force of Percuffion, which he leaves indefinite, and thinks fuffici- ent to force any quiefcent finite Refiftance whatfo- ever.
~ But as this Account and Hypothefis are part of a Pofthumous Work (if a liberty of Conjecture
_ may be allow’d in fo uncertain a Matter,) I fhou’d fafpect, that thefe Papers were left unfinifh’d by
Borellus ; ot at leaft, that in many places the laft Hand was never putto them. For neither in this Place, nor any other of this Work, does he account for any more than the Sy/fole of the Heart, and the refiftance which is made to the progreflive motion of the Blood in the Arteries ‘only. This alone he found to exceed the Pow- er of the Heart fo prodigioufly, that he feems to fhuffle it off his Hands with a general and
. “precarious Solution, as a difficulty that he was defirous to be rid of. For, having afcrib’d this _ flupendous (as he himfelf calls ic) effect to the Energy of Percuffion, he takes no care to {atisfic his Reader any farther about it, or to refer him,
_ or give him the expectation of Satisfaction any _
where elfe ; although he has an exprefs Treatifé
‘on the Force of Perevffiony which was written Pte a na N 4. preparar
cel SaaS. 3
184 Miaifcellanea Curiofa.
preparatory to this, and to which he frequently refers in other Places of this Work. But what confirms my fufpicion, that this part was intend- ed for a farther Revife by the Author, is, that he has left the Progrefs of the Blood through the Veins, and the Diaftole of the Heart, abfolutely untouch’d, tho’ they are Difficulties of a much greater magnitude than this, which he has at- tempted to account fo flightly for : For, in thefe the is excluded the benefit of Percuffion, and has
yet a greater refiftance to overcome without it.
Omiftions of this kind are fo unufual with this Author, where-ever he knows himfelf to go up- ‘on fure grounds, that it is to me an Argu- ment, that he doubted the fufficience of his Pere
cuffion, and referv'd thefe important Phenomena :
for farther Confideration, without plunging him- felf into fuch an Abfurdity, as to afcribe to Per-
cuffion any {uch Energy as to be able (fo broken
‘as it returns to the Heart) by its re-adction to
force that Power, from whence-.only it was at
firft deriv’d,
Dr. Lower, and Mr. Cowper, deliver their Opi- nions of the Caufe of the Dilatation of the Heart
fo very fhort, and without any Arguments to
fupport them, that by expofing them. naked, they feem rather to difcourfe of it tranfiently, —
as Men oblig’d by tae Nature of their Sub-
jects to fay fomething of it, than felicitous to | give any full or fatisfaCtory Account ; and there-
fore I fhall proceed no farther ‘upon them
here. ‘ pat 2h.
But though the Hyporhefis or Borellus may in this. Cafe, be found precarious or infufhcient
(a Misfore
eee sy
Mi ‘fellanea Curiofe. ae
fa ‘Misfortune that has befallen him in divers — other Particulars) his Theory holds ftill good. At
leaft it ought to be allow’d, in juftice to. his great | Abilities and Exaétnefs, till fome Body convicts him of fome. material Error in his Calculations,
_ which. has not as yet been done by any Body, that I know of.
Suppofing then the force of the Eleart, and of the Mufeular Coat of the Arteries, as likewife of
_ the refiftance, which they muft overcome, to be
computed with any degree of accuracy, there re- mains yet fuch a prodigious difproportion to be ac- counted for, as requires fome more powerful Agent,
Fe than any yet aflign’d, to make up the deficiency.
What affiftance the Heart receives from the
~ aétion of the Thorax towards the facili itating its
Contra&tion, without which afliftance there cata have been no Sy/tole, has. been already fhewn. But neither the Inrercoftal Mutcles, or Diaphragm, ‘which are fo inftrumental in that part of its
‘aétion, .can contribute any thing. to the Diaftole ;
-‘becau‘e they ferve only to enlarge the Cavity of
‘the Thorax, and thereby to open a paffage to
the Blood from the Heart, and prego its Con-
ftriGion. ee “Whatever thereforé the force i is, ‘that dil dil ates 2s the Heart, and is the, caufe of the Diaftole, it mutt be
“equal to that of che Heart, the Intercoftal Mufcles
ie Re: to all which it a€ts.as an Antayo- oc take no notice. of the Ser ratus Major An-
| ‘Ficus, and other Mutcles which have an ob{cure ‘hare in the Elevation of the Coffe, becaufe as
much 1 may reafonably be deducted upon the ac-
count , of the .Obliguus externus. Abdominisy and
Me o Mufcles 5 which ig their Infertions on
elaoels., ie ~ towards
\ tik aia. 186 ©Mifcellanea Curiofa,
towards the Depreffion of them, and fo balance the Account, But the chief ufe of thefe is in violent — Refpiration : In ordinary Refpiration their fhare is {mall, | :
Such a real Power (which may in the leaft be fufpefted of any fhare in this Action) is hard, perhaps impoffible to be found in the Machine of any Animal Body; and yet without fome fuch Antagonift, it is as impoflible the Circulation of the Blood fhould be maintain’d. All the En- gines yet difcover’d within the Body, confpire to- wards the Conftrifion of the Heart, which is the State of Quiefcence, to which it naturally tends, Yet we find it alternately in a State of Violence, that is, of Dilatation; and this upon neceffity, ee upon this 4/ternation depends all Animal
ife. : ~ Some fufficient Caufe External muft there- fore be found, to produce this great Phenome= zon ; Which Caufe muft be either in the Air, or Atmofphere, becaufe we have no conftant and immediate Commerce with any other Medi- wMS« a ik _ Some great Phyficians obferving this, and that depriv’d by whatfoever means of Communication ‘with the external Air, we became inftantly ex- tinGt,, have imagin’d, that in the At of Infpira- tion certain purer parts of the Air, mixed with the Blood in the Lungs, and was convey’d with it to the Heart, where it nourifh’d a fort of Vital Flame, ‘which was the Caufe of this reciprocal A/fus of the Heart. Others not quite fo grofs, rejecting an Aual Flame, have oie that thefe fine Parts of Air mixing with the Blood in the Ventri- cles of the Heart, produc’d an Effervefcence which dilated it: But thele Fatcies have been long
fince
Mifcellanea Cuviofa. 187 fince exploded and condemn’d upon ample Con- » viction ; and ’tis a Point yet undetermin’d, whe- ther any Air does mix with the Blood at all in the Lungs, or not. | 7
But fuppofing, that fome Air may infinuate it felf into the Pulmonary Vein, it can no other way dilate the Heart than by an Effervefcence in the Left Ventricle, which wou'd not dilate ‘the Right. But this Opinion is contradicted by Antopfie, and too laborioufly confuted by others, to be brought upon the Stage again here? | ;
‘There remains therefore only the grofs Body of the Armofphere to be confidered, whis is undoub- tedly the true Antagonift to all thofe Mutcles, which ferve for ordinary Infpiration, and the Conftriftion of the Heart. This will appear more evidently, if we confider not only the Power, but the Neceffity of its A€tion upon Ani- mal Bodies, as well as the want of other fuffici- ent Agents, i
The Heart is a Solitary Mufcle of very great ftrength, and the Intercoftal Mufcles and Dia- phragm, which likewife have no Antagonifts, are a vaft additional Force, which mutt ‘be balanc’d by the contrary Action of fome equivalent Power or other. For, tho’ the ACtion of the Intercoftal _ Mufcles be voluntary, that does not exempt them
from the condition of all other Mufcles ferving for voluntary motion, which wou’d be in a State ‘of perpetual Contraftion, notwithftanding any Influence of the Will, were it not for the Libra- tion of Antagonift Mufcles. ‘This Libration be- tween other Mufcles, is anfwer’d by the Weight of the incumbent Armofphere, which preffes upon _ the Thorax and other parts of the Body. And, ios as
188 Mifceilanea Curiofa. | as in all other voluntary Motions the influence of the Will only gives a prevalence to one of its two Powers before equilibrated, fo here it ferves ‘to enable thofe Mufcles to lift up a weight too ponderous for their ftrength not fo affifted ; and therefore as foon as that affittance is with-; drawn, the Coffe are again deprefsd by the meer Gravitation of the Atmofphere, which woud otherwife remain elevated through the na-, tural Tendency of thofe Mufcles. to Contra- étion. i | ng This is evidently prov’d from the Torricellian’ Experiments, and thofe made upon Animals in Mr. Boyle’s Engine ; where, as foon as the Air is withdrawn, and the preffure thereby taken off. the Intercoftal Mufcles and Diaphragm are con-. tracted, and the Ribs elevated in an inftant, and. can’t by any Power of the Will be made to fub-. fide, till the Air is again let in to bear them for- cibly down. ‘aes It were fcarce worth while to take notice here of a Miftake of the Learned Dr. Willis, were it. not for the great Authority of the Man, which is almoft fufficient to keep Error in countenance,, — _ ., The Do@tor having obferv’d, Tee gee that the Fibres of the External; NBO we Bet ht amA teed Intercoftal Mufcles ran in a contrary order, as it were, decuflating | each other, takes occafion from thence to. fanfse, — that there was an oppofition in their Office 5 and: that as the External ferv’d to raife up, the Ribs, — the Internal drew them down again, forgetting: ‘ at that time, That, when a contractile Body is faften’d at the feveral ends to Points unequally, . ~ moveable, Jet. the Contraétion happen in what, : "part or manner foever, the more moveable Point, muft _
hs catia am t 1 a ay ite A A Mifcellanea Curiofa. 189 muft be drawn towards the lefs moveable: By which Rule, whether Exrernal or Internal Inter- coftals be contracted, the lower Ribs will be forc’d to approach the upper, that is, be rais’d
up. : oe in the Elevation of the Cote, the Blood, by the paffage that is open’d for it, is in a manner folicited into the Lungs; fo in the Depreffion of them, by the fubfidence of the Lungs, and | the Contraction of the Blood-Veflels, both which are confequent thereof, the Blood is forcibly driven, as it were with an Embolum, through the Pulmonary Vein into the Left Ventricle of the Heart. And this, together with the general Compreffion of the Body by the weight of the Ar- mofpbere, which furrounds and prefles upon the whole Surface of it, is that Power which caufes the Blood to mount in the Veins, after the force imprefsd upon it by the Heart is broken and | fpent, and which 1s fufficient to force the Heart from its natural State to Dilatation, | ~ Hie that is able to compute the weight of a Column of Air, equal to the Surface of the whole Body, will readily grant ix a power fuf- “ficient for the Effects, which are here alcrib’'d to it. And when he confiders, that the Bo- dies of Animals are compreffible Machines, he will find that it muft of neceflity affe@ them “in the manner here laid down. But though our Bodies be entirely compos'd of Tubuli, or ‘Weffels filld with Fluids ; yet this preflure, how great foever, being equal, cou’d have no effect upon them, if the fuperficial Dimenfions vere not eafily variable ; becaufe being come prefsd on all parts with the fame degree of Force, the contain’d Fluids cou’d not any i saa : : “where
tear
ere
190 Maifcellanea Curiofa.
where begin to recede, and make way for thé reft to follow, but wou’d remain as fix’d and im- moveable as if they were aClually folid. But by the Dilatation of the Thorax, room is made for the Fluids to. move, and by the Coarétation of it, frefh motion is impreft, which is the main Spring whereby the Circulation is fet and kept going. | ;
This reciprocal Dilatation and ContraGtion of - the fuperficial Dimenfions of the Body, feems fo neceflary to Animal Life, that there is not any Animal fo imperfect as to want it, at leaft none to the inward Structure, of which our Anato-— mical Difcoveries have yet reach’d. For, tho” moft kinds of Fifh and Infe&s, want both move- able Ribs and Lungs, and confequently have no dilatable Thorax, yet that want is made up to em by an Analogous Mechanifm, anfwering fuffici- ently the Neceflities of their Life. a
Thofe Fifhes which have no Lungs, have Gills, which do the Office of Lungs, receiving and ex- pelling alternately the Water, whereby the Blood-— Veffels faffer the fame alteration of Dimenfions, that they do in the Lungs of more perfeét Ani- mals, | ae The Lungs or Air-Veffels of Infects, are yet exceedingly more different in Structure, Diftr bution, and Situation from thofe of perfect Ani- mals, than thofe of Fifhes are, and yet in their Ufe and Action agree perfectly with both; that is, recetving and expelling the Air, and varying the Dimenfions and Capacities of the Blood-Veffels. Thefe having no Thorax, or fe- pa Cavity for the Heart and Air-Veffels,
have the latter diftributed through the whole Trunk of their Bodies, by which they commu-
nicate i
4 > 7
es Mifeellanea Curiofa. 19}
nicate with the External Air ergs feveral Spivacula or Vent-holes, to which are faften’d fo many little Trachee, or Wind-pipes, which thence fend their Branches to all the Maufcles and 7- cera, and féem to accompany the Blood-Vefiels all-over the Body, as they do in the Lungs, on- ly of perfe& Animals. By this difpofition in every Infpiration, the whole Body of thefe little Animals is inflated, and in every Expiration _comprefs’d ; and confequently the Blood-Veflels muft fuffer a Viciffitude of Extenfion and Con- traction, and a greater motion muft thereby be imprefs’d upon the Fluids contain’d in them, than the Heart, which does not in thofe Crea- tures appear to be Mufcular, feems capable of giving. | -
The only Animal that is exempted from this
-neceflary condition of Breathing, or receiving and — expelling alternately fome Fluid into and out of the Body, is a Fetus, But this, while included in the Womb, has little more than a vegetative Life, and ought fcarce to be reckon’d among the number of Animals. For, were it not for that fmall fhare of Mufeular Motion, which it “exercifes. in the Womb, it might without abfur- _ dity be accaunted foras a Graft upon, or Branch of the Mother.
Concerning the immediate Matter, and Means of Life, and Nutrition, Authors are not a- greed, nor is it the bufinefs of this place to econcile, or decide their Differences, but to account for the Motion of the Blood through ‘the Veffels only. In order to this, it wiil be neceflary to obferve, that the Pulfation of the Heart in a Fetus is fo very weak and objcure, and the Motion of the Blood fo extream flows
any r , an
192 Mifcellanea Curiofa. i and languid, as to be. fcarce, if at all percei- vable, as has been ‘experienced in the Dif-— fection of Puppies before Refpiration had. ‘To he produce fuch a feeble Palpi- Boyle of the tation, and creeping Motion, ere rah no greater force feems to be eris €F Alimenti vequired, than may he deriv’d dofe Eu. from the Communication be- tween the Veflels of the Moe ther and Fweus in the Placenta. I, am not ig- morant, that divers very Learned Anatomitts — ( whom the Crowd have implicitly follow) have abfolutely rejeGted all Communication between thefe Veffels. But, with fubmitfion to Great Authorities, 1 ‘think they have acted arbitrarily, and without fufficient Warrant from Reafon or Experiment: For neither are © the Arguments which they bring againft it conclufive, nor the Office which they affign to the Umbilical Veffels in lieu of it, proper, or natural to thofe Veffels, or the reality of the Fact made out by any fubftantial Reafons. Thofe that rejeét this Communication ufuall do it in favour of one or both of thefe Opini- — ons, that the Arteries of the Uterus do ee fite a Nutritive Juice, or a Juice impregnate with. Air in the Placenta, which is fuck’d in by the Umbilical Vein, and conveyd to the Fe- tus, for the neceflary Ufes of Nutrition and Life. Now. thofe that patronize either of — thefe Opinions, lead Nature an unneceflary Dance. For if the Maternal Blood does. wal dy contain any fuch Nutritious, or any fuch neceflary Aerial Particles, why fhoud they be feparated and extravafated, to be with difhie culty receiv'd into the Umbilical Vein, and a> : | gain
a
hand
| hafaliagals A ee . | ’ er ‘ ie Mifcellanea Curiofa. 1932 again mixt with the Blood, when they might more éafily have been imparted by the plain {im- ple way of Transfufion from the Arteries of the Mother to the Veins of the Fetus. And, that this is the courfe which Nature takes in this ‘Cafe, I am perfwaded from the eafinefs and fim- plicity of the Method, which readily performs what might be perhaps in vain expected from — the other, and wou'd over and above find them, _ what they feem to grope fo blindly about for, a . firft Mover of the Blood in a Fetus. _ Thofe that contend for the conveyance of the _ Natricious Juice, through the Umbilical Vein from the Placenta, are forc’d upon two Difficulties next to Abfurdities. For firft they are oblig’d - to make this Vein, which, as all other Veins, - feems dedicated to the Re-conveyance of Blood _ only, the proper and immediate Chanel, thro’ _ which a very dierent Liquour is to be carried ; ’ and next, to give a Power of Attraftion or Su- b tion to it; becaufe the Nutricious Juice, which it is thus deftin’d to carry, is both vifcous and - ftagnant, and has neither force to drive, nor _ fubtilty to penetrate, or infinuate it felf into the | Capillary Veins ; and therefore muft be drawn "or fuck’d as Milk is from the Breaft, to which the Placenta and iss Nutricious Juice are by the ' Favourers of them exprefly compard. But if "this were the fole ufe of the Placenta, and Ume- a bilical Veffels, why were the Umbilical Arreries fent along with the Vein? Their bufinefs is - fot to bring any thing back to the Fetus, nor
1
i.
_. of the Morher ; for the Urerine Arteries bring ca all to the Placenta, the Umbilical Vein car- “ ries it to the Ferus, and the Uterine Veins con- ert O eee vey.
WENN a aN 5
194 Mifcellanea Curiofa: vey back again the Surcharge of the Mother's Blood ; the Umbilical Arteries only, have nothing to do, and are fuperfluous and impertinent, which is contrary to the conftant Pra@ice of "Nature. Yet if Autopfie did in the leaft_coun- tenance this Hypothefis, fome Defence might {till be made; but we find in the Umbilical Vein of a Fetus nothing but Florid Blood, fuch as in all probabiliry it received immediately from the Arteries of the Mother without any mixture. And therefore I can’t help conclud- ing, that this Opinion engages its Favourers in mies ARE, without Neceflity and without Proof. : They that from the Placenta {upply the Body of the Fetus with Azr, are as much diftrefs'd as
\
tother ; for they are fore’'d to beg the Queftion
twice, which, even when granted, will not an- — fwer their Ends. Firft, they fuppofe, that an —
intimate mixture or confufion of Air with the
Blood, is neceflary for the er of Animal h
Life, a Poftulatum, which perhaps the former part of this Difcourfe may have render’d unne-
ceflary ; and next, that the Fetus is fupply’d
with Air from, and its Blood mix’d with ic in the ©
Placenta. | a But here again they fetch a Compafs without
neceflity or proof. For if a mixture of Air were —
neceflary to a Fetus, why fhould it be fepara- ted from the Mother's Blood, and not rather both communicated together, fince it is fo much more eafie and commodious? But neither does the Placenta feem to be inftru@ed and pro-
vided for the feparation of Air, but of a much —
groffer Fluid, deftin’d to fome other ufe, which Auropfie confirms: Yet, were both thefe Opi-
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a“
Pome ee ee oy a
Mifcellanea Curiofa. 195 nions true, they are however defective, and the Circular Motion of the Blood unprovided as | aa : By the way of Transfufion, this great Pheno- — menon is naturally accounted for, and the Ends, for which the other two Hypothefes were de- _ vis'd, might both be anfwer’d with more cafe. For the Hyfterick Arteries tranfmitting their Blood immediately to the Umbilical Vein, may very, eafily tranfmit fuch Nutricious Juices or Aerial Particles, as are contain’d in the Blood, - along with it, without depofiting them by the _ way. By this means fo much of the Impulfe _ of the Mother’s Blood is preferv’d, as futtices _ to maintain that languid Circulation which a Fetus enjoys. For the Blood being driven ? through the Arteries of the Uverus into the _ Unmbilical Vein, is convey’d directly to the Si- | nus of the Porta, and thence by a fhort and _ dire&t Paflage through the Cava to the Heart ; _ where paffing through the Feramen Ovale to the Left Ventricle, and through the Canalis Arteriofus _ from the Right and Pulmonary Artery, it is all deliver’d without coming at the Lungs to’ the _ Aorta, and from thence again by the Umbilical Arteries to the Veins of the Uterus, making a fort Of Epicycle to the main Circulation in the Mo-
A eg Oe
5
_ conceiv’d, or repugnant to Experience. : Late ‘DifCoveries' have made it appear, that the Ar- _ teries and Veins are continu'd. Tubes, and that the latter contain nothing but what they receive _ from the former, and no Reafon appears why a | O02 we
* - Fe Fu y ra aes ee ag!” c) Pde le ek. SAS. aN AD a awa ene pata we D » ‘ f ee
196. Mifcellanea Curiofa. ‘we fhou'd think this Method to be varied in the Placenta. On the other hand, if the Arteries of. the Urerus were continued to the Veins of the fame part, and thofe of the Fetus in like man- ner, without communicating with each other, their Confluence in the Placenta feems to be alto- gether impertinent, and of no ufe, and the. Um- bilical Arteries and Vein fram’d for no other — Service or Purpofe, than to give the Blood room for an idle Sally. Ty he |
_ Thus the Reafonablenefs of this old Opinion may be vindicated, but the Certainty of it refts upon ftronger Proof. Mr. Cowper, to whofe hap- py Induftry we owe the Confimation of many ancient Difcoveries, and the Benefic of fome new ones, has the Honour to re-eftablifh this old, but long exploded ‘Truth. For by pouring
Mercury into a Branch of the Userine. Arterie Of a Cow, that went into one of the Cotyledones of the Urerus, he fill’d thofe Branches of the Um- — bilical Veins, which went from that Cotyledon to the Navel of the Fetus; which, with a part of the Urerus, he keeps prepared by him. et
It would be a weak Objeétion, to alledge, .
That the Obfervation and Experiment being made on the Urerus of a Cow, the Inference would not hold from thence to a Woman, the one being Glanduliferous, and the other Placenti- ferous 5. Rive every one of thefe Cotyledones, or. Uterine Glandules, is in all refpects a little Placenta, and all the difference between them is in number, name, and magnitude. Why Rz- minanes differ in this Particular from other Vivi- parous Animals, is befide the Subject of our pre- fent Enquiry. But the great Flux of Blood, which centtantly follows upon drawing the Pla-
| centa
ts A las eae
Mifcellanea Curiofa, -197 centa from Women (whichis frequently fo great asto coft them their Lives) is as plain a de- ‘monftration to Reafon of the Continuity of the ~Veffels, as Mr. Cowper’s Experimens is to the Eye. beet 4 r
{ have heard it obje&ted by very Learned - Men, that if there were fuch a Conrinuity of Vef- fels, and fuch Transfufion of Blood, the Fetus muft neceffarily perifh through lofs of Blood, upon the feparation of the Placenta from. the Urerus ; but that, on the contrary, no vifible Flux of Blood.does follow while the Fetus con- tinues wrapt in the Membrane, in which Cone dition it-may be kept alive fome Hours. To this ic may be anfwer'd, that the Circulation in ‘the Ferus, being deriv’d from the Mother, may _-be fuppos’d wholly to ceafe upon the cutting ‘off the Communication between them, till it is pos renew’d more forcibly: by Refpiration. But if we allow the motion already imprefs’d upon *the’ Blood to be fufficient to keep it going a itrle while ; yet it muft needs be {0 exceeding — ‘languid, that the meer‘refiftance of the Exter- »nal Air muft be more than enough to hinder any Efflux of Blood from a Fetus before Re- fpiration. How long Life may be prefery’d without an a@ual Circulation of the Blood, is a Queftion not of this place. But we have been ‘convine’d by many and. notorious Obfervations and Experiments, that Life has been recover’d va long time after all tokens of Refpiration, Cic- culation, or even. Life it felf, have difappear’d ; fo that we can’t think the firft Solution either “ampofflible or improbable. | ITS Ly at y, ay
re 3 ry " a | ory ? OT {
su oye Mane
198 Mifcellanea Curiofa.
ae
I expeét to be told, that im the early Days
OF Geftation in’ Viviparous|Animals, there is no Pla-
venta, or any Adhefion of the Umbilical Vef- fels to any part of the Mother, and conféquent- ly no fuch Transfufion ; and that in Ovipareus there is no continuity, Or communication of Vet-
“fels of any kind, during the whole time of In-
)
‘cubation. mm But thefe Objections carry neither the Weight nor Difficulty along with them, that they may be fuppos’d to do; for in thofe Days there is neither Blood or Blood-Veffels, and confequent- ly there can be no Circulation of the Blood ; and the Embryo, of what Species foever, is no more than a Vegetable at that time ; nor does the Ferus of any Viviparous Creature enjoy any Circulation, or fhew any figns of Ani- mal Life, till after thofe Veflels, as well as others requifite to the Circulation, are com- pleated. rout Ye age 3 Tr muft be confefs'd, that Oviparous Animals are denied the benefit of this Communication ; ‘but that want is fufiiciently compenfated by a peculiar Mechanifm, which direétly anfwers the
ends of Refpiration, and the preffure: of the Ar-
“mofpere upon the Fetus. There is at the ob=
zufe end of an Egg a fmall Cavity fill’d with Air, which is the fuccedaneous Inftrument to the Refpiratory Organs. For~-as foon as the Contents begin to be warm’d by the Incubation ef the Hen, or any analogous Heat of Furnace or
_Dunghil, the feveral Humours of the Egg re-
quire a fermentative motion, and the Air cor tain d in the Cavity or Veficle, at the obtufe end of the Egg, is rarefied, and the Veficle extended
and enlarg’d, and confequently the other Con-
"tents
a P
iy rt Rey
Mifcellanea Curiofa. 199 tents are compreft; to which the fermentative motion naturally refifts. But both Bodies be- ing as well compreffible -as dilatable, and both having an expanfive motion impreft upon them by Incubation, the Compreflion and Renitency. will be mutual, but varied in degree, accord- ing as either, through the variation of Circum- ftances, fhall prevail. By this means, an Al- ternation of Compreffion and Dilatation will be _produc’d in both, anfwering the re/piratory mo- tion, by which a motion will be communica- ted, which, as foon as the Organs by which
a it fhould be regulated are compleated, will in
the Body of the Pullus be regular and circulas tory. get Fabritius ab Aquapendente, and after him, our
_ Great Dr. Harvey, have affign’d divers Ufes to
this Cavity or Air Veficle, the Extravagance of
which have perhaps: deterr’d others from enqui- ring fo. much into the Ufe, as the Importance
of it requir'd. But though I can’t agree to that
Perfpiration, Refrigeration, and Refpiration, which
they make ic the Inftrument of ; yet perhaps
_ the 4ir, that was inclos’d in that Cavity, may
through the Augmentation of the Body of the
~ Pullus, and its own Rarefa&tion (which is at laft
fo great as to occupy half the Shell) break the Membrane, which feparated it from the Pu/-
Jus, and thereby give fo much Refpiration as to
“form the chirping. Voice, which is often heard
before the breaking of the Shell, and with it ive an addition of Strength to enable ic to break e Shell. But how it fhould re(pire fooner, is
to me inconceivable.
1@) 4 There
PARC +o RIVET
200 = Mifcellanea Curiofa. There are many Problems of great feeming Difficulty, the Solutions of which flow naturally from what has been laid down here: But intend- ing to profecute this Subje& farther, and to treat of the Impediments of Refpiration, and the Confequences of Refpiration obftruéted or in- termitted, I fhall referve them for that Oppor- tunity, and content my felf here to attempt the’ Harveyan Problem only, which has given abun- dance of Authors fo much perplexity. , That incomparable Philofopher enquires, 7hy a Foetus, taken out of the Uterus with the Mem- | branes intire, fhall live in Water fome Hours with- out communication with the External Air; whereas if it be taken out and fuffer'd once to breath, it cane afterwards furvive a Moment without the benefit of Refpiration. _ C 2H 9 SM Pe BSI Granting the Fa& to be as he has deliver’d it, which yet is not fo in all Cafes, the main Difh- culty is grounded on a Miftake, which from the {tating of the Queftion I find this Great Man . to have flipt into. For he thinks, that a Fetus is fooner fuffocated after having once breath’d, than if it had not breath’d at all, and that by breathing it had contracted fomething which render’d it more perifhable. Idem tamen fecundis exutus, (fayshe) fi femel aerem sntra Pulmones attraxerit, poftea ne momentum quidem temporis ab{que eo durare poffit, fed confeftim moriatur.’ And - prefently after, Siquidem conftat, feetum,. poftquam eum femel bauferit, citius fuffocari 5 quam cum ab illo prorfus accebatur. | The Doctor obferving a Fetus to live longer without Refpiration, and to difpence better with the. want of Air while included in the Membranes intire, than it cou’d afterwards ; infers thence, that the Air does in
the
—Mifcellanea Curiofa. 101 the firft AG of Infpiration imprefs' upon the Lungs fome quality, which renders it ever af- ter more indifpenfably neceflary. But allowing his Obfervation, I muft yet deny his Inference to be good : For deprive a Fetus of means of re- fpiring, and then take it out of the Membranes, and it fhall be as foon fuffocated, as if it had refpired before. This proves, that this ne- _ ceflity of intercourfe with the Air, by way of the Lungs, is not the Offspring, but the Pa- _ rent of Refpiration, and that, that Learned Man was drawn into a Fallacy of Non caufa pro Caufae |
The Reafon of this Necefity is the preffure of the External Air upon the Surface of the Bo- dy, from which it was defended by the Interpo- fition of the Membranes, and the Humours con- taind, which are not fo compreffible as the Bo- dy of the Fetus it felf. So foon therefore as the Fatus is excluded, and exposd to the immedi- _ ate contact of the ambient Atmofphere, the Vef- fels and all the Cavities of the Body muft ne- - ceffarily be fo comprefs’d, that the Fluids can’t _ have room for motion, and-confequently the Fetus could have no Life, if Nature had not con- triv’d by the motion of the Thorax to remove and admit that preffure alternately, and there- by to imprefs a motion on the Fluids, which is _ the Spring of Life. But this motion of the
Thorax being any way fupprefsd, the equal —
preflure of the Atmofphere on all parts, occa- fions a total Ceflation of motion, which is Death. | , I fhall profecute this Subje& no farther now, nor trouble the Reader with any Apology, for _ diffenting from thofe Great Men herein named; i : becaufe, |
oR eet *, fo
r =e /
202 Mifcellanea Euriofa. becaufé, I hope, I have done it with Modefty, and all thé Refpect due to fo great Authorities, and have aflign’d nothing which is not Matter of Fa& uncontroverted, or deduc'd from it by plain Mechanical Neceflity. OE,
Same
Mifcellanea Curiofe. 203
Son Thoughts Wa Expirimenis
concerning Vegetation. By John Woodward, M. D. of the Col- lege of Phyfici fcians, and R.S. and
ig Profs efor of Phyfick in Grefham
, aa
: r [ IHE Ancients generally intitled the Eareh
to the ProduGion of the Animals, Vege- tables, and. other Bodies upon and about it ; and that for that Reafon *twas, that they gave it fo frequently the Epithets of Parent. and Morher*.. They were of * Terra Parens.
opinion, that it furnifhed forth Ti untrue zlvlar, the Matter whereof thofe Bo- Terra Matter.
dies confift ; and receiv’d it all
back again at their Diffolution for the Genspoftire of others. Even thofe who. afferted four Elements, fuppofed that the Earth was the Matter that cor-
Jiituted thofe Bodies; and that, Water and the
irefts fery’d only for the Conveyance and Diftribu-
tion of that Magter, in order to the forming and
__compofition of them. 7Tis true, Thales, a Philo-
fopher of . the firkt Rank ‘in thof.early-Ages, has been thought to have Sentiments very different
from thefe ; but that without jut Grounds, as
T think I toc fufficiently prov'd i in another Pa- ae pbb A am psy to aii ¥
v mi oy tk ‘ ¢ Moe But
* 904 Mifcellanea Curiofa. But though Antiquity thus gave its Vote for Terreflrial Matter, feveral of the Moderns, and fome of very great Name too, both here and abroad, have gone quite counter, and given theirs in behalf of Wazer. The Dignity of the g Perfons that have efpoufed it, as well as their — Numbers, renders this Doétrine very. confide- rable, and well worth our enquiring into. The great. Reftorer of Philofophy in this laft Age, my Lord. Bacon, is of Opinion, That for Nourifbment of Vegetables, the Water is almoft all in all, and that the Earth doth but keep the Plant upripht, and fave it from + Nat. Hiftory, over-heat, and over-coldj. O- Cent. 5-§.411. thers there are who are ftill : | more exprefs ; and affert Wa- ter to be the only Principle or Ingredient of © all Natural Things. They fuppofe. that, I can- not tell by what Procefs of Nature, Water is tran{muted into Stones, into Plants, and in brief, 2 Gibb exiition - all other Subltances whatever. atque Miftion, E- neath particularly, and lement. Figm. his Followers, are very pofitive in this 5 and offer fome Ex- periments to render it credible. Nay, a very : : Extraordinary Perfon of our + Mr. Boyle, Scept. own “Nation f tries thofe Ex- Chym. pare 2- = periments over again; and | -- difcovers a great i ee the fame Thoughts and Opinion they had-; de. claring for this Tranfmutation of Water into “Plants and other. Bodies, though with ‘great Mo-. defty and Deference, which was his ‘uftal man ner. sei ee S| Ria The Experiments they infift upon “ate chiefly two; the fir is, that Mint, and feveral other | , Plants
Mifcellanea Curiofa. 205
Plants profper and thrive very greatly in Water.
. The other is this; they take a certain quantity
of Earth, and bake it in an Oven; then the
weigh it, and put it into an Earthen Pos. Ha- ving well water’d “this Earth, they make choice of fome fit Plant, which, being firft carefully weigh'd, they fer in it. There they let it grow,
Continuing to water it for fome time, till ’tis much advanced in bignefs: Then they take it
up; and though the Bulk and Wight of the Plant be much greater than when firft fer, yet upon’ baking the Earth, and weighing it, as at firft, they find it little or nor at all diminifhed in weight ; and therefore conclude, “tis not the Earth but Water, that nourifhes and is turn'd into the Subftance of the Plant.
. I muft confefs I cannot fee how this Experi-
‘ment can ever be made with the mi cety and juftnefs
that is requifite, in order to build upon it fo
much as thefe Gentlemen do. "Tis hard to weigh _ Earth in that quantity, or Plants of the fixe of
‘thofe they mention, with any great exattne/s ; or to bake the Earth with that accuracy, as to
- reduce it twice to juft the fame Drinefs. But I
may wave allthis; for though the Experiment be never fo eafily praCticable, and all the Acci- dents of it exa@ly as they fet forth, yet nothing ‘Tike what they infer can poflibly be concluded
from it 5 unlefs Water, which they fo plentifully
, ‘beftow upon the Plant in chis Experiment, be pure,
“homogeneous, and not charged with any’ terreftti-
al Mixture’; for if it be, the’ Plant after all
"may owe its Growth and Encreafe intirely to that. :
3
-Some
2 OURS Oe Se sapreteuas oh hie: Ba A : Wee er % xy
206 Mifcellanea Curiofa. Some Waters are indeed fo very clear and tranfparent, that one would not eafily fufpect any ‘erreftrial Matter were latent in them ; but they may be highly faturated with fuch Matter, though the Eye be not prefently able to decfry or difcern it.. "Tis true, Earth 1s an Opake Body; but it may be fo far. diffolved, reduced to fo extreme fmall Particles, and thefe fo diffufed through the watry Mafs, as not fenfibly to impede Vifion, or render the Water much the lefs diaphanous. Silver is an Opake, and indeed a very denfe Body; and yet, if perfectly diffolved in, Spirit of, Nitre,. or A- qua Fortis, that is reétified- and thorowly fine, _ it does not darken the _ * Provided the Silver _Menftruum, or render it be pure and abfolutely lefs pellucid than before™. refin’d : For the leaft And other Inftances there admixture of Copper are, that oftentimes great will produceablueTin- C bate al oe. “ure in the Menftru- <2#antities Of Opake Mat um5 as that of fome. ter are fuftain in Fluids y other Bodies, ove dif- without confiderably ftri- ferent. = =. king the Eye, or being per- | ... ceiv’diby at. So that were — there Water any where found fo pure, that the _ quickeft Eye could difcover in it no terreftrial Antermixture; that would be far hort of a Proof
that in reality there was none. Saige) ... But after all, even the cleareft Water 1s very far from being pure and wholly defecate, in any ‘part, of the World that I can learn. For ours here, I have had an Opportunity of examin- ing it over a good part of England ; and can- not fay I ever met with any, that, however frefh and newly taken out of the Spring, did not exhibit, even to the naked Eye, great om
Ea sae |
7
4 e
— Mifcellanea Curiofa. 207 numbers of exceeding {mall terreftrial Particles difleminated through all parts of it, Thicker and crafler Water exhibits them in ftill greater Hee a :
Thefe are of two general kinds. The one a vegetable terreftrial Matter, confifting of vee ry different Corpufcles; fome whereof are pro- per for the formation and increment of one fort of Plant, and fome of another ; as alfo fome for the Nourifhment of one part of the fame Plant, and fome of another. ‘The other kind of Particles fuftain’d in Water are of a Mine« ral Nature. Thefe likewife are of different forts. In fome Springs we find common Salt, ) in others Vitriol, in others Alum, Nitrey Sparrs Ochre, &c. nay, frequently feveral of thefe, or other Minerals, all in the fame Spring 3 the Water as it drains and pafles thorough’ the Strata of Stone, Earth, and the like, tam king up and bearing along fuch loofe Mines ral Corpufcles, as it meets with in the Pores and Interftices of thofe Strats, and bringing _ them on with it quite to the Spring. All Water whatever is much charg’d with the Ve= -getable Matter, this being fine, light, and eafie ly moveable. For-the Mineral, the Water of Springs contains more of ir than that of Ri- vers, efpecially when at diftance from their ‘Sources; and that of Rivers more than the ‘Water that falls in Rain: This I have learn’d from feveral Trials, which I mutt not give Ac- count of here; my Drift in this place being only to evince the Exiftence of Terreftrial Mat- ter in Water. © CM bala
Any
EVA ae
208 Mifcellanea Curiofa. Any one who defires farther Satisfa@tion in this, may eafily obtain it, if he only put. Wa- ter into a clear. Glafs Viol, ftopping it clofe, to keep Duft and other extericr Matter out,
A Rate Oa ¥
i eer ee i:
f
and letting it ftand, without ftining it for —
fome Days: He will then find a confiderable Quantity of terreftrial Matter in the Water, however pure and free it might appear when firft put into the Viol. He will in avery fhort time obferve, as I have frequently done, the Corpuicles that were at firft, while the Wa- ter was agitated and kept in motion, fepa-
~ yates and hardly vifible *,
kT fy nothing by degrees, as the Water
of thofe that were permits, by its becomingmore
not difeernible. "Lill and at reft, affemblin and combining together ; by
that means forming fomewhat larger and more
~confpicuous Molecule. Afterwards: he may be-
hold thefe joining and fixing each. to other, . by that means forming large thin Maffes, ap-
pearing like Nubecule, of Clouds in the Wa-
ter; which grow more thick and opake, by
_ the continual appulfe and accretion of frefh
-_
Matter. If the {aid Matter be chiefly of the’
Vegetable kind, it will be fuftain’d in the
Water; and difcover at length a green Co-
Jour, becoming ftill more and more of that’ Colour, I mean an higher and more faturate —
Green, as the Matter thickens ‘and encreafes. That this. Matter inclines fo much to that Co- Jour, is the lefs ftrange, fince we fee fo large a fhare of it, when conftituting Vegetables
‘wearing the fame Colour in them. But if
there be any confiderable’ quantity of meer Mineral Matter in the Water, this, being
Bs
Mifcellanea Curiofa. 209 of a greater fpecifick Gravity than the Vegeta- ble, as the Particles of it unite and combine in fuch Number, till they form a Molecula, the Impetus of whofe Gravity furpaffes that of the Refiftance of the Water, fubfides a great deal of it to the bottom. Nor does it only fall down it felf, but frequently entangling with the Vegetable Nubecule, forces them down along with 1t. ‘aGa8 The Reafon why Bodies, when diffolved and reduced to extreme {mall Parts, are fuftain’d in Liquors that are of lefs {pecifick Gravity than. thofe Bodies are, hath been pointed at by 2 late ingenious Member of this Society *. He is indeed far *Mr.W. Moli« from having adjufted all the eux, Pbilofophi- Momenta of this Affair ; how- °4/7747/.No.181- ever it muft be admitted, thar, in the dividing or folution of Bodies, their Sur- faces do not decreafé in the fame Proportion _ that their Bulk does. Now the Gravity of a Body, which is the Caufe of its finking or ten- dency downwards, is commenfurate to its
_ Bulk; but the refiftance that the Liquor makes,
is proportion’d, not to the Bulk, but to the Extent of the Surface of the Body immerfed in it. Whence ’tis plain, a Body may be ‘o far divided, that its Parts may be fuftain’d in a
_ Fluid, whofe fpecifick Gravity is lefs than that
of the faid Body. Nay, ‘tis Matter of Fact, _ that they frequently are fo; and we daily fee Menftrua fapporting the Parts of Metals, and other Bodies, that are of fix, ten, nay, almoft ‘twenty times the fpecifick Gravity of thofe Menftrua. And as the Parts of Bodies when divided, are thus fupported in a Fluid; fo | P when
210 Mifcellanea Curiofa. when they occur and unite again, they muft fink of courfe, and fall to the Bor- tom. ae bi gE a Ay Upon the whole, ’tis palpable and beyond rea- fonable Conteft, that Water contains in it a very confiderable Quantity of terreftrial Matter. Now the Queftion is, te which of théfé, the. Water,
eer Ree ee bes ious <a
or the Earthly Matter fuftain’d-in it, Vegeta-
bles owe their Growth and Augment : - For de- ciding of which, I conceive the following Expe- riments may afford fome Light}? and 1 can- fafely fay, they were made with ‘due Care and
ExaGinefs. | SE se Die, AES PVE
3 Anno 1691;
“Tchofe feveral Glafs Vials, that were all, as near as pollible, of the fame fhape and big- nefs. “After 1 had’ put what ‘Water I thought fic into every one of them, and taken an Ac- count of the weight of it, I ftrain’d and ty'd over the Orifice of each Vial, a Piece of Parch- ment, having an hole in «the middle of it, large ‘enough to admit’ the Stem of the Planr I defign’d to fet in the Vial, without confining or ftreightning it, fo as to impede its Growth. My Intention in this, was to prevent the in- clofed Water from evaporating, or afcending any other way than only through the Plant to be fer therein. "Then I made choice of fe- veral Sprigs of Mint, and other Plants, that were, as near as I could poffibly judge, alike frefh, found, and lively.’ Having taken the weight of each, I placed it in a Vial, order’d as above ; and as the Plant imbib'd and drew off the Water, I took care to add more Of the
; : fame
«
} Sopepersen gos
x‘
"pills C curiae ari fame from time to time, keeping an Account
of the weight of all I added. Each of the Glafles were, for better diftin@tion, and the
more eafie keeping a Regifter of all. Circum-
flances, noted. with a different Mark or .Let- ter, A, B, C, ec. and all.fet in a Row in. the fame Window, in fuch manner that all might partake alike of Air, Light, and sun. ‘Thus
‘they continued from Fuly the Twentieth, to ‘O@ober the Fifth, which was jut Seventy Se-
ven Days. Then I took them out, weigh’d the
Water ia each Vial, and the Plant likewile, ‘adding to’ its. weight that of all the Leaves
that had fallen off - during the time it ftood thus. And Laftly, I> ¢éomputed how much each Plant had gain’d 3; and how much Water
“was {pent upon ic Lhe Particulars are as
follow.
d (as, Common Spear-Mint, fee. in Spring We-
“ter. The Planted weighed when put in, Fuly
* 20. juft 27 Grains ; when taken forth, Odober
* 5. 42 Grains: So that in this face of 77 ‘ Days, it had ‘gained in weight 15 Grains.
© The whole Quantity of Water expended, du-
* ring thefe 77 Days, amounted to 2558 Grains.
* Confequeitly the weight of the Water taken
“UP was 1707p times as much as the an had “ got. in PRB : a 3
«(B,) Coheee Spear-Mint, Rain Water. ‘The € Mint weigh’d, when put in, Gr. 281; whea ‘taken out Gr. 459 jks mee in 77 Days
"Gr. 17% ae Sale ;
P 2 eh pe
er es ret wee aed Toe SNR Salih i ‘; '
212 Mifcellanea Curiofa. . * The Difpendium of the Water Gr. 3004,
which was 1713} times as much as the Plant “had receiyed in: weight. _ Me.
"8 (C!) Comman Speai-mint, eblmtar pales 1 Be © Plant when put in, Gr. 28, when taken forth, “Gr. 54. So that in 77 Days it had gained
PS A we
“©The Water expended, ninibunted to Gr. © 2493. which was 9533 times as much as the * additional weight of the Mint. |
* (D.) Comm on Solanum, or Night-fhade : Spring= ‘ water. The Plant weigh’d, when put in, Gr. © 49; whenitaken out, 106 ; having gain’d in 77 * Days 57 Gr. | :
“ The Water expended during the faid time, € was 3708 Gr. which was 6525 times as much “as the Augment of the Plant. 4
© This Specimen bad feveral Buds upon it, when
_ © firft fec in the Water. Thefe in fome Days be- "© came fair Flowers, which were at length fucceed- -
~ “Sed ‘by Berries...
(EY Lathyris feu Cataputia Gerb. Spring- =... ° Water It’ weigh’d, when put in, Gr. 98. “when taken ‘forth, Gr. 1013. The additional > * “weight for the whole 77 Days, being but * Gr. 32. WU ai . zs The Quantity of Water fpent upon it during © that time, Gr. 2501. which is 7144 times as ae a much as the Plant was augmented. _ me fees |
ilk Several other Plants were ery’d, that did ‘a CY - ‘ ig * ;
not thrive in Water, or Succeed. any Metter than the Cataputia foregoing : | : «Bute
Mifcellanea Curiofa. 213 But ’tis befides my purpofe to give a par= cular Account of them here.
(F,G.) Thefe Two Vials were fill’d, the former (F) with Rain, the other with Spring-water, at the fame time as_ thofe above-mention’d were ; and ftood as long -as they did. But they had neither of them any Plant; my Defign in thefe being only to inform my felt, whether - any Water exhaled out of the Glaffes, other. wife-than thorow the Bodies of the Plants. The Orifices of thefe two Glafles were cover'd with Parchment ; each piece of it being perforated with an hole of the fame bignefs with thofe of the Vials above. In this 1 fufpended a bit of Stick, about “the thicknefs of the Stem of one of the aforefaid Plants, but not reaching down : to the Surface of the included Water. I put - them in thus, that the Water in thefe might mot have more Scope to evaporate than that - in the other Vials. Thus they ftood the whole 77 Days in the fame Window with the reft ; when, upon Examination, I found none of the Water in thefé wafted or gone off. Tho’ I obferved both in thefe, and the reft, e — fpecially after hot Weather, fmall Drops of Water, not unlike Dew, adhering to: the In-’ fides of the Glaffes, that Part of them, I: mean, ’ _ that was above the Surface. of the’ enclofed We Warepa Gar i004 017) ovors of gy net bed | The Water in thefe two Glaffes that had no Plants in them, at the'end of the Experiment, exhibited a larger Quantity of _Terreftrial Mat- ter than that in any of thofe that had the Plants in them: did!) The »Sediment at the bottom:.of the Vials was greater; and the * doh 2 a Nubecule —
SEE SO ate eee ee ae 214 “Mifellanee Curivfa,
Nubecule, diffus'd through the Body of the Wa-
ter, thicker. And. of that which was in the o-
thers, fome of ir proceeded from certain {mall
Leaves that bad fallen from that part ofthe ‘Scems of the. Plants that. was within the. Water,
wherein they rotted and-diffolved... The:'Ter- reftrial Matter in the Rain-water was finer: thin
that in the Spring watt fiorls “aad
> Anni ipa 4H The Glaffes alla ufe Pl in bale were of | the fame fort with: thofe in-the former Expe- riment; and coverd over with Parchment in like manner. The Plants here were all Spear- mint ; the moft kindly, ‘frefh, fprightly Shoors I-could chufe: "The Water, ‘and- the. Plants: were weigh’d as above; and the: Vials fet in) a: Line, in. a South Window : where they f{tood” Gaul Fune the 2d. to Fuly 28, which was. ae : 56! way hiw wobm WW Set | sags NN ‘(HL Hyde-Park: Gonddies Wael, ge: a The: < Mint! weighed; whem put in, 127 Gre when. “taken out, 2959°Gr.. "Ehe whole Quantityi-of | ‘ Water expended. sant barae ahr epee: | *to 14190°Gr fo » ilsie) sit ‘to gobi ‘This was all aichges a wery: kindly Blaneg: 32 ‘and had run up to above two Foot in heighti/ “It had fhot but“ one :confiderable ‘éollatéral * Branch ; but had: fenr:forth ‘many)!and dong’ Roots; “from which fprung, very: numerous,: ’ though {mall and: fhort,Jeffer Fibres, © ‘Thefé. * leffer:Roots came out of the larger on two ‘op. ope pe for the: 18 part 3 fo thavveach: 5 Root,
“~
‘
Mifcellanea Curiafa. 215
* Root, with its Fibrilfe, appear’d. not unlike
‘4 fmall Feather. To thele Fibille adher’d * pretty mult Terreftrial Matter. In the Wa. © ter, which was at laft thick and turbid, was a ‘ green Subftance, elembiing a fine Bp Con-
‘Servae Bh os | ee Atha
mee" ) The fame Watery “alone. The Ming
* weigh’d, when put. in, 110 Gr. when taken * out, 249. Water expended, 13140Gr.
© This Plant was as kiadly as the former, but ‘ had fhot. no collateral Branches. Its Roots, © the Water, and the green Saag, all much
‘ as in the former. "
ie (K.) Hyde-Park Pf RULOK, in which was 6 diffolved an Ounce and half of Common Garden,
i ©. earch. The Mint weigh’d, when ‘put in, 76 " Gr eewbap taken out, 244 Gr.., » Water hd
week.’
rf cca: eh pee ont, of re aes |
t adhering to the Extremities of them. The * fame green Subltance here, that was inthe twe
eprecading.
ag fe es &
i _&(L) a Rakin, wit the ime Sen:
ie ‘ty of Garden-mould as. in the former. The
* Mint weigh’d, when put in, 92 Gr. when ta-
wn ken ~-0ut, - 376 Gr, , The Water expended — hargg5o. ltl foe a
: one os ene : ae oti: : (Yt
Nee igh i Na eile isn ea
¥ a
eee Nh Rae NT mee 2 Mere
216 Mifcellanea Curiofa.
© This Plant was far more flourifhing than any ° of the precedent; had feveral very. confiderable * collateral Branches, and very numerous Roots, * to which Terreftrial Matter adhered very co- § pioufly. St palived
‘The Earth in both thefe Glaffes was very © fenfibly and confiderably wafted, and lefs than * when firft put in. The fame fort of green : Subftance here as in thofe above. ;
“(M) Hyde-Park Water, diftilled off with a * gentle Still. The Minz weigh’d, when put in, © 114 Gr. when taken out 155. ‘The Water ex- ~ * pended, 8803 Gr. , * This Plant was pretty kindly ; had two {mall * collateral Branches, and feveral Roots, though * not fo many as that in H or J, but ‘as much © Terreftrial Matter adhering to them as thofe ‘had. The Water was pretty thick’; having * very numerous {mall Terreftrial Particles fwim- * ming in it, and fome Sediment at the bottom “ of the Glafs. This Glafs had none of the green * Matter above mentioned, in it = =>
©(N) The Refidue of the Water, which re- © main’d in the Szs// after that in M, was diftilfd “ off. It was very turbid, and as high-colour’d — © (reddifh) as ordinary Beer. The Mint weigh’d, € when put in, 81 Gr. when taken out, 175 ¢ Gr. Water expended, 4.344 Gr. This Plant “ was very lively ; and had fent out fix collate- * ral Branches, and feveral Roots. = (O.) Hyde-Park Conduit-watey, m which was — diffolved a Drachm of Nitre. The Mint fet. in this fuddenly began to wither and a :
a
Mifcellanea Curiofa. 217 and died in a few Days: As likewife. did two more Sprigs, that were fet in it, fucceffively, In another Glafs J diffolv’d an Ounce of good Garden-mould, and a Drachm of Nitre, and in a third, half an Ounce of Wood afhes, and a Drachm of Nitre ; but the Plants in thefe fuc- ceeded no better than in the former. In other Glaffes 1 diffolved feveral other forts of Earths, Clays, Marles, and variety of Manures, &c. I fet Mine in diftil?d Mint-water ; and other Experiments’ I made, of feveral kinds, in order — to get Light and Information, what haftened or’ retarded, promoted or impeded Vegetation ; but thefe do not belong to the Head I am now upon. — Hid-4.
» (P.) Hyde- Park Conduit-water. In this I fix’d a Glafs-‘Tube about ten Inches long, the Bore about one fixth of an Inch in Diameter, fill’d with very fine and white Sand, which I kept from falling down out of the Tube into’ the Vial, by tying a thin piece of Silk over that end of the Tube that was downwards. Upon Immerfion of the lower end of it into the Wa- ter, this by little and. little afcended quite to the upper Orifice of the Tube. And yet, in all the fifty fix Days which it ftood thus, a very inconfiderable Quantity of Water. had gone off, viz. fcarce twenty Grains; though the Sand continued moift up .to the top ull. the very laft.. The Water had imparted a: green Tin@ture to the Sand, quite to the.very top of the Tube. And, in the Vial, it had pre- cipitated a greenifh Sediment, mix’d with black, To the bottom and fides of the Tube, as far as “¢was immer’d in the sibsaashd 3 ob de aye erd
518 Mjfellanes Guofas
her’d pretty much of the green Subftance de- {crib'd above. Other like Tubes I ‘fill’d with - Cotton, Lint, Pith of Elder; and feveral o- ther porous Vegetable Subftances 5. ferting fome of them in clear Water ; others im Water tinged with Saffron, Cochinele, Ge... And -fe- veral. other. Trials were made, ia. order té give a mechanical Repreféentation of the \ motion and diftribution of the Juices in Plants ; and of fome. other Phenomena: obfervable in’ Vege- tation, which’ L -fhall not give the Particulars “ here, as binge not bak uf to bese —, dee ae ie : a 8 gi"
telieNt R,S, a. Seuncal Peat: et in, Vials ordered in like manner as thofe above, in O@o- ber, and the following ‘colder Months." ‘Thefe throve not near: fo much; nor did) the Water afcend in nigh the quantity it did in the: better Seafons, in which the before recited Trials were made. vie ik He ia soit )
eh}
Some 5 Refi ittn: ‘Be a faci Be
2 RET HE va ahi
a iE sd ta: sing eyes ‘an A Sal Ie Plénts\iof the fame ‘kind, the def they are in Balk, the fumnaller the ‘Quantity ‘of the fluid Mafs, in -which' they are Sets is? drawn off 5 3 the Difpendium- of it 5 where “the Mafs' as a equal thicknefs, being pretty ‘nelarly proportion’ vi to” the Bulk of the - Plants’ Thus” that “in the Gf mark’d A, which weigh’d only'27 Grains, ° drew off but’ 2558 Grains of the Fluid and that in’ B,- which» weigh’d only 2815 took “up” but re Grains ; “whereas ® ‘that! WER? Which
t ve weigh’d
bin, thie
Mifcellanea Curiofa. 219 weigh’d 127 Grains, fpent 14.190 Grains of the — Liquid Nase mt The Water feems to afcend.up the Veffels of Plants, in much the fame manner as up a Filtre ; and .*tis no great wonder that a larger: Filtre fhould draw off more. Water than a leffer; or. that a Plant that has more and larger Veflels, fhould take up'a greater fhare of the Fluid in which it is fer, than one that has fewer and fmaller, ones can. , Nor do | note this as a thing . very confiderable in it felf, but. chiefly in. regard ‘to what,J am about to, offer beneath ; and that. it may be feen that, in my other Collations of Things;, 1. made due Allowance for this Dif fapameOomiocnds “Qo cus tb |
pet cuowe bos vib witin ae
2. The much greateft part of the fluid Mafs,. that is.thusdravn off and convey'd into the Plants, does “not :fertle or: abide there ; but, paffes through the pores of them, and exhales up into the Atmo= Spbere.. “Fat the Water in thefe Experiments afcended ;only ‘through the Veflels of the, Plants, is-certain... Phe Glaffes F and G, ,that had no. Plants if them, though difpofed of in’ like man-_ ner as-the refts remain‘d at. the End: of the Ex- periment, as’ at. firft ;. and none. of the, Water was goné!off. “And that the greateft part of it flies, off from the Plant into, the Atmofphere, is as certain. "The Jeaft Proportion of the Water expended, was to the Augment of the Plant, asi46 or 50 tort, »And in fome the weight of the Water drawn: off was 100, 200, nay, in one above:700..times.as much as the Plant had received of Addition:
potmm ow .2taslT io 2a a
SOM, S18 yout yr sie) alt yo oSi<
arowmun eo This
%~
YB oad
}
$3
ae a RET Ne, lees a
220 © Mifcellanea Curiofa.
This fo continual an Emiffion and Detach- ment of Water, in fo great Plenty from the Parts of Plants, affords us a manifeft Reafon why Countries that abound with ‘Trees, and the’ larger Vegetables efpecially, fhould be very ob- noxious to Damps, great Humidity “in the Air,.and more frequent Rains, than. others that are more open and free. ‘The great Moi- {ture in the Air, was a mighty inconvenience and annoyance to thofe who firft fettled in - America ; which at that time was much over-’ grown with Woods and Groves, But as thefe were burnt and deftroy’d, to make way for Habitation and Culture of the Earth, the Air mended and clear’d up apace, changing into a Temper much more dry and ferene than before. ile Pe Soe a
Nor does this Humidity go off pure and a=: lone ; but ufvially bears forth with it many Parts) of the fame Nature with thofe whereof the Plant, through which it pafles, confifts. The Craffer indeed are not fo eafily born up into the At- mofphere ; but are ufually depofited on the Sur- face of the Flowers, Leaves, and other Parts of | - the Plants: Hence comes our Manna’s, our Hoe: neys, and other Gummious Exfudations. of Ve- getables.. But the finer and lighter Parts are with greater eafe fent up into the Atmofphere,: Thence they are conveyed to our Organs of: Smell, by the Air we draw in Refpiration ; and> are pleafant or offenfive, beneficent or injurious: to ‘us, according to the Nature’ of the Plants’ from whence they -arife. And fince . thefe.owe.
.
their Rife to the Water, that-afcends out of the, Earth through the Bodies of Plants, we cannot be far to feck for the Caufe why they are more
a | | numerous
— MifcellaneaCuriofa. 221 numerous in the Air, and we find. a greater quantity of Odors exhaling from Vegetables,
in warm, humid Seafons, than in any other whatever.
: a A great part of the Terreftrial Matter that is mix'd with the Watery afcends up into the Plant as mell as the Water. There was much more Terreftrial Matter at the end of the Experi- ment, in the Water of the Glafles F and G, that had no Plants in them, than in thofe that had Plants. The Garden-mould diffolyed in ‘the Glaffes K and L, was confiderably dimi- nifhed, and carried off. Nay, the Terreftrial vand Vegetable Matter was bora up in the ‘Tubes fill'd with Sand, Cotton, €&c. in that Quantity, as to be evident even to Senfe. And the Bodies in the Cavities of the other ‘Tubes, that had their lower Ends immers’d in ‘Water, wherein Saffron Cochinele, &c, had - been infufed, were tinged with Yellow, Pur- ple, Ge. , if | _ If I may be permitted to look abroad a while, towards our Shores and Parts within the Verge of the Sea, thefe will prefent us ‘with a large Scene of Plants, that, along with the Vegetable, take up into them meer mine- «ral Matter alfo in great abundance. Such: are sour Sea-Purflains, the feveral forts of Alga’s, of “Sampires, and other marine Plants. Thee contain’ common Sea-falt, which is all one with the Foff/, in, fuch plenty, as’ not only to be “plainly diftinguifh’d on the Palate, but may ‘be drawn forth of them in confiderable Quan- tity. Nay, there want not thofeé who afirm, “there are Plants found that will yield Nitre,
and
Ne Re ee
238 Mipielanea Ginisfe.
and other thineral ‘Salts ; of which indeed [ am not fo far fatisfied, that-1 can depend on the Thing, and therefore give this only as an hint for Enquiry.
To go on with the Veperable: om how apt and how much difpofed this, being f fo ves ry fine end light, is to attend Water in all its Motions , and follow it into each of its Recefles, is manifelt, not only from’ 'the~ In- ftances above alledg’d, but many ‘others. © Per- colate it withal ‘the Care imaginable ; Fil- ter it with never fo many Filtrations, | yet fome Terreftrial Matter will remain.’ “Tis true, the Fluid will be thinner every time than other, and more er He of the ‘faid Matter ; but never wholly free and clear. - I have filtred Water thorough feveral wholly free and clear Sheets of thick Paper; and, af- ter that, through very clofe fine Cloth: twelve times doubled. Nay, IT have done this over and over; and yet a confiderable quantity of this Matter difcover’d it felf in. the Water af- ter all. Now if ic thus pafs Interftices,, Lia are fo very fmall and fine along with the ter, ‘tis the lefS ftrange it fhould attend ir! “f its paflage through the Du@ts and Veflels’ of Plants. *Tis' true, filtering and ‘diftilling of Water intercepts and makes it quit fome of ithe Earthy Matter it was before impregnated withal : But then that which continues” with the Water after’ this, is fine and. light . and fuch confequently, as is in’ a peculiar man- ner fit for the Growth and Nourifhment of Vegetables. And this is the Cale of Rain- water. The Quanticy of Terreftrial Matter it bears up into the Atmofphere, is not get ut
—— Mifcellanea Curiofa. 223 But that which it does bear up, is mainly of that light kind of Vegetable Matrer ; and that too perfectly diffolved, and reduced to fingle Corpulcles, ali fit to enter the Tubules. and Veflels of Plants: On which Account’ "tis, that this Water. is fo very’ fertile and pro- he Reafon, why in this Propofition, I fay, ly a great part of the ‘Terreftrial Mat- ter that is mix with the Water, afcends up with it into the Flant,’is,. becaufe all of it cannot. ‘The Mineral Matter is a great deal of it, mot only grofs and ponderous, but fca- brous and) inflexible; and fo not difpofed to enter the Pores of the Rovts. And a great many of the fimple Vegetable Particles by de- grees unite, and form fome of them. {mall Clods or Molecule; fuch as thofe mention’d ia EK, ound lls, {ticking to the Extremities of the Roots of thofe Plants, Others of them intangle in a loofer manner ; and form the Nubecule, and green Bodies, fo commonly ob- ferv'd in ftagnant: Water. Thefe, when thus €onjoin’d; are too big to: enter the Pores, or afcend up the Véflels of Plants, which fingly they’ might have done.. They who are con- verlant in Agriculture, will eafily fubfcribe to this. They are well aware that, be their Earth never fo °rich, fo good, and fo fit for the ‘production of Corn or other Vegetables, lit- tle will conie of it, unlef the Parts of it be fparated and loofe. ’Tis “on. this Account they beftow the Pains they do in Culture’ of it, in Digging, Plowing, Harrowing, and Breaking ‘of ‘the Clodded Lumps of arth. ?Tis the fame way that Sea-falr, Nitre, me Sr otner
name
224 Mifcellanea Curiofa. q other Salts, promote Vegetation. I am forry” 1 cannot fubfcribe to the Opinion of thofe © Learned Gentlemen, who imagine Nitre to ; be effential to Plants; and that nothing in- the Vegetable Kingdom is tranfacted without it, By all the Trials I have been able to make, the thing is quite otherwife ; and when contiguous to the Plant, it rather def goys than nourifhes it. But. this WNitre and: ot er Salts certainly do 3 they loofen the Earth, and {eparate the concreted Parts of it ; by that means fitting and difpofing them to be affumed by the Water, ‘and carried up into the Seed or Plant, for its Formation and Augment. There’s no Man but mutt obferve, how apt all forts: of Salts are to be wrought upon by Moi- fture ; how eafily they liquate and run with it ; and when thefe are drawn off, and have deferted the Lumps wherewith they were in- corporated, thofe miit moulder immediately, and fall afunder of Courfe. The hardeft Stone we meet with, if it happen, as fre- quently it does, to have any fort of Salt in- rermix'd with the Sand, of which it confifts, upon being exposd to an humid Air, in a fhort time diffolves and crumbles all to pieces; and much more will clodded Earth or Clay, which is not of near fo. compact and. {o- lid a Conftitution as Stone is. “Ihe fame way ikewife is Lime ferviceable in this Affair. The Hlusbandmen fay of it, that it does not fatten, but only mellows the Ground: By which they mean, that it does not contain any thing in it felf that is of the fame Nature with the Vegetable Mould,» or afford any Matter fit for the Formation of Plants; but
) meerly
4 .
Mifcellanea Curiofa. 225
meerly foftens and relaxes the Earth ; by that means rendering it more capable of entering the Seeds and Vegetables fet in it, in order to their -Nourifhment, than otherwife it would have been. The Properties: of Lime are’ well known ; and how apt ’tis to be put into Ferment and Commo- tion by Water. Nor can fuch Commotio ever happen when Lime is mix’d with Earth, however hard and clodded:that may be, without opening and loofening of it,
— d The Plant % more or lefs nouri(hd and aug- mented, in Proportion as the Water, in which it (tands, contains a greater or fmaller Quantity of proper terreftial Matter in it. The Truth of this Propofition is fo eminently difcernable through the whole Procefs of thefe Trials, that I think no doubt can be made of it. The Mint in the Glafs C, was of much the fame Bulk and Weight with thofe in A and B, But the Water, in which that was, being _ River-water, which was apparently ftored more - copioufly with terreftrial Matter, than the _ Spring or Rain-water, wherein they ftood, _ were 5 it had thriven to almoft double the Bulk that either of them had, and with a lefs _ Expence of Water too. So likewife the Mint in L, in whofe Water was. diflolved a {mall - quantity of good Garden-mould, though it had _ the difadvantage * to be lefs, beara . when firft fet, than either of « Confer. Prop.
the Mints in H or J, whofe 1. fapra
Water was the very fame .. with this in L, but had none of that Earth mixd with it ; yet, in a fhort time the Plant not only overtook, but much out-ttrip’d thofe and at the end of the Experiment was very
con-
226 = Mifcellanea Curiofa. — confiderably bigger and heavier than either of them. In like manner the Mine in N, though lefS at the beginning than that in M, being fet in that thick, turbid, feculent Water, that remain- ed behind, after that wherein M was placed, was {till’d off, had in fine more than double its ori- ginal weight and bulk ; and receiv’d above twice the additional Encreafe, than that in M, which food in the thinner diftilld Water, had done. And, which is not lefs confiderable, had not drawn off half the Quantity of Water that that bad. a preg ae Why, in the beginning of this Article, I li- mit the Proportion of the Augment. of the Plant to the Quantity of proper Terreftrial Matter in the Water, is, becaufe all, even the Vegetable . Matter, to fay nothing of the Mineral, is not proper for the Nourifhment of every Plant. There may be, and doubtlefs are, fome Parts in different Species of Plants, that may be much alike, and fo owe their Supply to the fame common Matter ; but ’tis plain all cannot. And there are other Parts fo differing, that tis” no ways credible they fhould be form’d all out “of the fame fort of Corpufcles. So far from it, that there want not good Indications, as we fhall fee by and by, that every kind of Vege- table requires a peculiar and fpecifick Matter for its Formation and Nourifhment, Yea, each Part of the fame Vegetable does fo; and there are very many and different Ingredients go to the Compofition of the fame individual Plant. If therefore the Soil, wherein any Vegetable or Seed is planted, contains all or moft of thefe Ingredients, and~thofe~in due quantity, it will grow and thrive there ; otherwife “twill ‘oe
th s be a8
0 HERE Are Be 4 Mi Mas tw ) + m i " % .
Miaifcellanea Curiofa. 227 If there be not as many forts of Corpufcles as are requifite for the Confticution of the main and more effential Parts of the Plant, ’ewiil not profper at all. If there be thefe, and not in fufheient Plenty, ‘twill ftarve, and never ar- ‘rive to its natural Stature: Or if there be any the lefS neceflary and effential Corpufcles wanes ting, there will be fome failure in the Plant; "twill be defeGive in Tafte, in Smell, in Colour, or fome other way.. Bur though a Tract of Land may happen not to contain Marrer proper for the Conftitution of fome one pecuiiar kind of Plant; yet ic’ may for feveral others, and thofe much differing among themfeives. ‘The Vegetative Particles are commix’d and blended in the arth, with a!l the diverfiry and variety, as well.as all the uncertainty, conceivable. J have'givenfome Intimations of this” elfewhere *, and {hall not repeat them here, but hope in due time - & fe to put them .into a much better Light tham that they there f{tand in. It is: mot poitible to imagine, how one uni- form, homogeneous’ Matter, having its Princt ‘ples or Original Parts all of the fame Subftance, Conftitution, Magnitude, Figure, and Gravit y, -fhould ever comftinate Bodies fo egregioufly un- ike, in all thofe. refpects, as Vegetables of dif. ferent kinds are 5. nay, even’ asi the > diflerent "Parts of the fame Vegetabld. That one fhould Carry a refinous, another a “milky, a third Ya yellow, a fourth a red*Juice, in its Veins; one af- ford a fragrant, another an offenfive Smeil ; one ‘be fweet to the Tafte, another bitter, acid, acerbe, auftere, €c.that: one fhould‘be nourifhing, ano- ther poifonous, one purging another aftringent: In ~ ht 0%, brief,
os TRY bea risk ce tat
228 Mifcellanea Curiofa.
brief, that there fhould be that vaft difference in them, in their feveral Conftitutions,, Makes, Properties, and Effects, and yet all arife from the very fame fort of Matter, would be very ftrange. And, to note by the by, this Argu- ment makes equally {trong againft thofe, who 1 {uppofe meer Water the Matters out of which all — Bodies are form’d. aii bide: iptee fs q The Cataputia in the Glafs E, received but ve- ry little Encreafe, only three Grains and an half all the while it ftood, though 2501 Grains of | Water were {pent upon it. I will not fay the Reafon was, becaufle that Water did not con- tain in it Matter fic and proper for the Nourifh- — ment of that peculiar and remarkable ‘Plant. © No, it may be the Water was not a proper. Me- dium for it to grow in; and we know there are — very many Plants that will not thrive in it. Too much of that Liquor, in fome Plants, may ‘probably burry the Terreftrial Matter thorough | their Veflels too faft for them to arreft and lay hold of it. Be that asic will, ’tis moft certain there are peculiar Soils that fuit particular Plants. In England, Cherries are obferv’d to fucceed beft in Kent; Apples in Herefordfhire 5 Saffron in. Cambridgefbire ; Wood in two or three of our Midland Counties; and Teazles in Somerfetfhires This is an Obfervation that hath held in all
z
at 4
ioe ict Sate 5nd
-Parts,| and indeed. in all Ages of the World. eal) 3 The moft ancient Writers of _ + Vide Varro- Husbandry + took notice of it 5 nem, Columellam, a satel eee ot . tS. "veliquos’ Rei and ate not wanting. in their Ruftice Scriprores. Rules. for making * choice of Bat uth Bee {uited to the Nature of each kind of Vegetable they thought valuable, ot
worth propagating. © tak «But,
ig % "
Roe aed ~
1s; a cal Sik aie he
pid
— Mifcellanea Curiofa. 9
But, which is a further Proof of what I am here endeavouring to advance, that Soil thar is once proper and fit for the Production of fome
one fort of Vegetable, does not ever continue
to be fo. No, in Tract of time it lofes that Property ; but fooner in fome Lands, and later in others: This is what all who are converfant in thefe things know very well. If Wheat, for Example, be fown upon a Traét of Land thar is proper for that Grain, the firft Crop will fuc-
_ ceed very well; and perhaps the fecond, and
the third, as long as the Ground is in Heart, as the Farmers fpeak ; but in a few Years twill produce no more, if fowed with that Corn : Some other Grain indeed it may, as Burley. And after this has been fown fo often, thar the
Land can bring forth no more of the fame, ir
may afterwards yield good Oats ; and, perhaps,
Peafe after them. At length “twill become bar- ren; the Vegetative Matter, that at firft ic
abounded withal, being educed forth of it by —
_ thofe fucceflive Crops, and moft of it born of. _ Each fort of Grain takes forth that peculiar _ Matter that is proper for its own Nourifh-
ment. Firft, the Wheat draws off thofe Par-
- ticles that fuit the Body of that Plant; the reft Tying all quiet and undifturbed the while. And
ae
ae
_ when the Earthhas yielded up all them, thofe that are proper for Barley, a different Grain, remain
‘ftill behind, till the fucceflive Crops of that
~ Gern fetch them forth too. And fo the Oats -
and Peafe, in their Turn; till in fine all is car- ried off, and the Earth in great meafure drain’d
Of that fort of Matter.
O,3 After
230 Mifcellanea Curiofa. -
After all which, that very ‘Tract of Land may be brought to produce another Series of the fame Vegetables ; but never till *tis fupplied with a2 new Fund of Matter, of like fort with that ic at firft contain’d. This Supply is made feveral ways: By the Grounds lying fallow for fome time, till the Rain has pour'd down a frefh Stock upon it: Or, by the Tiller’s Care in ma- nuring of it. And for farther Evidence that this Supply is in reality of like fort, we need on- Jy reflect a while upon thofe Manures that are — found by conftant Experience beft to promote Vegetation, and the Fruitfulnefs of the Earth. — Thefe are chiefly either parts of Vegetables, or of Animals ; which indeed either derive their own Nourifhment immediately from Vegetable Bodies, or from other Animals that do io. In particular, the Blood, Urine, and Excrements of Animals ; Shavings of Horns, and of Hoofs ; Hair, Wool, Feathers; calcin’d She'ls; Lees of Wine, and of Beer; Afhes of all forts of Ve- getable Bodies ;- Leaves, Straw, Roots, and Stub-
le, curn'd into the Earth by Plowings or other- — wife, to rot and diflolve there : Thefe, I fay, are our beft Manures; and, being Vegetable Subftances, when refunded back again into the” Earth, ferve for the Formation of other like Bodies. a: 3 , :
- Not wholly to confine our Thoughts to the Fields, let us luok a while into our Gardens ; where we fhall meet with fill farther Confir- mations of the fame thing. The Trees, Shrubs, and Herbs cultivated in thefe, after they have. continued in one Station, till they have deri- ved thence the greater part of the Matter fit for their Augment, will decay and degenerate,
od | unlefs
SP Saat ary ee lah
7 Mifcellanea Curiofa. 231 unlefs either frefh Earth, or fome fit Manure, be applied unto them. “Tis true, they may maintain themfelves there for fome time, by
fending forth Roots further and further to a
great Extent all round, to fetch in more remote Provifion ; but at laft all will fail; and they mutt either havea frefh Supply brought to them, or they themfelves be removed and tranfplanted to fome Place better furnifhed with Matter
for their Subfiftence. And accordingly Gardiners
-
‘ebferve, that Plants that have ftood a great
while in a Place, have longer Roots than ufual ;_
part of which they cut off, when they tranf- plant them to a frefh Soil, as now not of any
further ufe to them. All thefe Inftances, to pafs
over a.great many others that might be al- -Jedg’d, point forth a particular Terreftrial Mat- ter, and not Water, for the Subject to which Plants owe their Increafe. Were it Water on-
ly, there would he no need of Manures ; or of atranfplanting them from place to place. The
Rain falls in all Places alike; in this Field and
in) that indifferently; in one fide of an Or- chard or Garden, as well as another. Nor could there be any Reafon, why’a Trac of
Land fhould yield Wheat one Year, and not -the next; fince the Rain fhowers down alike in each. But I am fenfible I have carried on this
_ Article to too great a length; which yet on fo
_ample and extenfive a Subject, ’twas not ecafie
to avoid. Mh : i 5. Vegetables ave not form’d of Water 5 but of @ certain peculiar Terreftrial. Matter. It hath been fhewn, that there is a confiderable Quan- tity of this Matter contain’d both in Rain, Vode: Q. 4 | NOpEIne.,
232 «©Mifcellanea Curiofa.
£
Spring, and River-water: That the much grea- teft part of the fluid Mafs that afcends up-into Plants, does not fettle or abide there, but pafles through the Pores of them, and exbales up. into the Atmofphere: That a great part of the Terreftrial Matter, mix’d with the Water, : paf- fes up into the Plant along with it; and that — the Plant is more or lefs augmented in propor- tion, as the Water contains a greater or {mal- Jer Quantity of that Matter. From all which | we may very reafonably infer, that Earzh,- and — not Water, is the Matter that conflitutes Vegeta- i bles. The Plant in E, drew up into it 2501 | Grains of the fluid MafS ; and yet had received but Grains 3 and a half of Increafe from all that. The Mint in L, though it had ar firft
the difadvantage to be much lef than that in I; _
yet being fet in Water wherewith Earth was ~ plentifully mix’d, and thar in I, only in Water — without any fuch additional Earth, it had vaftly outgrown the other, weighing at laft 145 Grains more than that did, and fo having gain’d about twice as much as that had. In like manner that in K, though "twas a great deal lefs when put in than that in J, and alfo was impaird and of-— fended by Infeéts; yet being planted in Wa- ter wherein Earth was .diffolved, whereas the Water in which it ftood had none, it not only — over-took, but confiderably furpafsd the other ;
_weghing at laft 29 Grains more than that in I,
and yet had notexpended fo much Water as that, by above 2400 Grains. The Plant in N, tho’ at firft a great deal lefs than that in M; yet being fet in the foul crafs Water that was left in the Sull, after that, in which M was fet, was drawn off, in Conclufion had gain’d in sone ‘
Cet. eM ai Me S
ee eed Si
i a, eae ee he! ee a aoe | Mifcellanea Curisfa. 233 above double what that in the finer and thin- ner Water had. The Proportion of the Aug- — ‘ment of that. Plant that’ throve moft was, ‘to - the fluid Mafs fpent upon it, but as 1 to 46. In others, “twas but as 1 to 60, 100, 200; nay, in the Cataputia, ‘twas but as 1 to 714. The Mint in B took up 39 Grains of Water a- day, one day with another; which. was much more than the whole weight of the Plant ori- ginally; and yet, with all this, it gain’d nor one fourth of a Grain a-day in weight. Nay, that in H, took up 253 Grains a day of the Fluid.: Which was near twice.as much as its original weight, it weighing, when firft fet in the Water, but 127 Grains. And, afterall, the daily En- -oreafe of the Plant was no more than Grains 223, 6. Spring, and Rain-water, contain pretty near an equal Charge of Vegetable Matter; River-wa- ter more than either of them. The Plants in the Glaffes A, B, and C, were at firft of much the ' fame fize.and weight. At the End of the Expe- -rimenf, the Mint in A had gain’d 15 Grains out sof 2558 Grains of Spring-water; that in B, — _ Grains 17 and an half, out of 2004 Grains of Rain-water ; but thatm C had got 26 Grains out of only 2493 Grains of River-water. , [ do not found this Propofition folely upon thefe Tri- als; having made fome more, which I do not relate here, that agree weli enough with thefe. So _ that the Proportions here deliver’d, will hold for the main; but a ftriét and juft Comparifon is hardly to be expected. So far from it, that I make no doubt, but the Water that falls in Rain, at fome times, contains a greater fhare of Ter- reftrial Matter than that which falls at others.
A more»
= ge ee
re ay ohh Tee a Ae v g a
234 MifcellaneaCuriofa, A more powerful and intenfe Heat muft need® hurry up a larger quantity of that Matter a” long with the humid Vapours that form Rain, than one more feeble and remifs ever poflibly can. The Water of one Spring may flow forth with an higher Charge of this Matter, than that of another ; this depending partly upon the ‘quicknefs of the Ebullition of the Water, and partly upon the Quantity of that Matter latent in the Strara, through which the Fluid pafles, and the greater or lefs laxity of thofe Svrata. For 'the fame Reafon, the Water of one River may abound with it more than that of ano-— ther. Nay, the fame River, when much’ agi- tated, and in commotion, muft bear up more of it, than when it moves with lefs"rapidity and violence. That there is a great Quantity of this Matter in Rivers; and that it contributes. vaftly to the ordinary Fertility of the Earth, we _ have an illuftrious Inftance in the Nile, the Ganges, and other Rivers that yearly overflow the neigh- bouring Plains. Their Banks fhew the faireft and largeft Crops of any in the whole World. They are even loaded with the multitude of their Productions ; and thofe who have not feen them, will hardly be induced to believe ' the mighty Returns thofe Tracts make ig compari- fon of others, that have not the Benefit of like Inundations. — . ) hate
7. Water ferves only for a Vehicle to the Ter- reftrial Matter, which forms Vegetables 5 and does not it felf make any addition unto them. Where the proper Terreftrial Matter is wanting, the Plant is not augmented, though never fo much Water afcend into it. The Caraputia in E, took
td | up
~
gn lag oak om tieareen“s ahd yaa a SUM ik A i nts a 4 Y :
Mifeellanea Curiofa. ~ 235 up more Water than the Mint in C, and yet had grown but very little, having received only | three Grains and an half of additional weight; ‘whereas the other had received no lef$ than twenty fix Grains. ‘The Mint in I, was planted in the fame fort of Water as that in K, was 5 only the latter had Earth diflolved in the Wa- ter; and yet that drew off 13140 Grains of the Water, gaining it felf no more than 139 Grains in weight ; whereas the other took up but 10731 Grains of the Water, and was aug- mented 168 Grains in weight. Confequently — that fpent 2409 Grains more of the Water than this in K, did, and yet was not fo much encrea- “fed in weight as this by 29 Grains. ‘The Mint in M, ftood in the very fame kind of Water as that in N, did. But the Water in M, having much lefs Terreftrial Matter in it than that in N had, the Plant bore up 8803 Grains of it, gain- ing it felf only 41 Grains the while; whereas that in N drew off no more than 4.344 Grains, and yet was augmented 94 Grains. So that it fpent 4459 Grains of Water more than that did 5 and yet was not it felf fo much increafed in weight, as that was, by 52 Grains. This is both a very fair, and avery conclu4ive Inftance ; on which Account ’tis that 1 make oftner ufe — of it. Indeed they are all fo; and to add any thing further on this Head, will not be needful. : 7 ;
"Tis evident therefore Water is not the Mat- ter that compofes Vegetable Bodies. *Tis only the Agent that conveys that Matter to them ; that introduces and diftributes it to their feveral Parts for their Nourifhment. That Matter is fluggifh and unaétive, and would lie eternally
a | confin’d
aS ee) ee Ss Be Be i titan ae iia oe me SSA Ne, 1k Re p> ey
we exe
236 =Mifceilanea Curiofa, confin'd to its Beds of Earth, without ever ad-— vancing up into Plants, did not Water, or fome like Inftrument, fetch it forth and carry it un-— to them. ‘That therefore there is that plenti- tiful Provifion, and vaft Abundance of it fup-— plied to all Parts of the Earth, is a mark of a natural Providence fuperintending over the Globe - we inhabit ; and ordaining a due Difpenfation . of that Fluid, without the Miniftry of which the Noble Succeffion of Bodies we behold, Ani- : mals, Vegetables, and Mine * Conf. Nut. Hifts vals, would beall at a ftand *. Earth, p.47.&feq. But to keep to Plants, *tis uti & pe 128, Oe. = — manifeft Water, as well on othe this, as upon the other Hy- pothefis, is abfolutely neceflary in the Affair of Vegetation ; and it will not fucceed without it: Which indeed gave occafion to the Opi- nion, that Water ic felf nourifhed, and was changed into Vegetable Bodies. ‘They faw, though thefe were planted in a Soil never fo tich, fo happy, fo advantageous, nothing cameof it unlefs there was Water too in a confiderable quantity. And it muft be allow’d Vegetables will not come on or profper where that is wanting : But yet what thofe Gentlemen in- ferr'd thence, was not, we fee, well groun-
ded. his a This Fluid is capacitated for the Office here affign’d it feveral ways: By the Figure of its Parts ; which, as appears from many Experi- ments, is exactly and mathematically Spheri- cal; their Surfaces being perfe&tly polite, and without any the Jeaft Inequalities. “Tis evident, Corpufcles of fuch a Figure are eafily . fufcepti- ble of Motion, yea, far above any others what- | | ever;
i.
a
oy he BR EES I tea
——— Mifcellanea Curiofa. 237 ever; and confequently the moft capable of moving and conveying other Matter, that is not’ fo active and voluble. Then the Inter- vals of Bodies of thar Figure are, with re- fpect to their Bulk, of all others the largeit ; and fo the moft fitted to receive and enter. tain foreign Matter in them. Belides, as far as the Trials hitherto made inform us, the conitituent Corpufcles of Water are, each fing- Jy confider’d, abfolutely folid; and do not yield to the greateft External Force. This fecures their Figure againft any Alteration ; and the Intervals of the Corpufcles muft be always a- Tike. “By the latter, ‘twill be ever difpofed to receive Matter into it; and by the for- _ mer, when once received, to bear it on along with it. Water is further capacitated to be a Vehicle to this Matter, by the tenuity and - finenefs of the Corputcles of which it con: fits. We hardly know any Fluid in all Na. ture, except Pire, whofe conftituent Parts are fo exceeding fubtle and fiall as thofe of Wa- terare. They'll pals Pores and Interftices, thar _ neither Air nor any other Fluid will, ‘This enables them to enter the fineft Tubes and Veffels of Plants, and to introduce the Terreftri. al Matter; conveying it to all Parts of them ; _ whilft each, by means of Organs ‘tis endqwed with for the Purpofe, intercepts and affumes into it felf fuch Particles as are fuitable to its own Nature, letting the’ reft pafs on through the common Duéts. » Nay, we have almoft -every where Mechanical Inftances of much the fame Tenor. ’Tis obvious to every one, how _eafily and fuddenly Humidicy, or the Corpufcles of Water fuftained in the Air, pervade and ine
finuate
¥ £
BS 2 RS eR ao sti a2 a oe am 4s :
238 | Mi iba Curiofe.
finuate themfelves into Cords, however tightly twifted, into. Leather, Parchment, Vegetable Bodies, Wood, and the like. This it is that. fits them for Hygrometers ; and to meafure and determine the different quantities of Moifture — in the Air, in different Places and Seafons, How freely Water pafles and carries with it Terreftrial Matter , through - Filtres, Cola- tures, Diftillations, Gc. hath bean intimated al-
ready.
mw a
8. Water is not spill of performing this Of=
fice to Plants, unlefs affifted by a due Quantity of
Heat 5 and this muft concur, or Vegetation will not . fucceed. The Plants that were fet in the Glafles — Q, ‘Rs S, «ean Ofteher, and the following colder Months, had..not | near the quantity of Water fent up into them, or fo great an ad- — ditional Encreafe. by much, as thofe that were
fet in Fune, Fuly, and the hotter. *Tis plain Water has no. power, of moving it felf; or ri- fing to the vait height i. wiloes ia the siniove tall and lofty Plants. So far’ from this, that it does not appear, from any Difcovery yet made, that even its own Fluidity confifts in the inteftine. Motion of irs Parts ; whatever \ fome, otherwife very learned and knowing, Per- fons may have thought. There is no need of
any’ thing more, for folving all the Phenome- na of Fluidity, than fuch a Figure and Difpo-— fition of the, Parts, as Water has. Corpufcles of that make, and. that are all abfolutely Sphe-
rical, muft ftand fo very tickle and nicely — upon each other, as to be fulceptible of every
Impreffion ; ; and though not perpetually in Mo=
tien, yetmutt, be ever ready and liable tobe put into —
—
tera ee” Vek age Saree
Mifcellanea Guriofa. 239 into it, by any the’ flighteft Force imaginable. It is true, the Parts of Fire or Heat are not ca- pable of moving themfelves any more than thofe of Water; but they are more fubtil, light, and aétive, than thofe are, and fo more eafily: put into Motion.. In fine, ’tis evident and matter of Fact, that: Heat does operate upon, and move © the Water, in order to its carrying on the Work of Vegetation : But how. 'tis agitated it felf, and where the Motion firft begins, this isno fit Place to enquire. ache (iat ,
That the Concourfe -of Heat. in this. Work is really neceflary, appears, not only from the ‘Experiments before us, but fom all Natute of from our Kields and Fore{ts, our Gardens and our Orchards, We fee in Autumn, as the Sun’s Power grows gradually lefs and lefs, fo its Ef- feéts on Plants is remitted, and their Vegeta- tion flackens by little and little. Its Failure as firft difcernible in Trees. ‘Thefé are raifed shigheft above the Earth; and require a more intenfe Heat to elevate the Water, charged with their Nourifhment, to the Tops and Extre- ‘meties of them. So thar for want of frefh Support and Nuttiment, they fhed their Leaves, unlefs fecur’d by a very firm and hardy Con- ftiturion indeed, as our ever-Greens are. Next the Shrubs part with theirs; and. then the “Herbs and lower Tribes ; the Heat being at length not fufficient to fupply even thefe, ‘though fo near the Earth, the Fund of . their Nourifhment...-As the Heat returns the fuc- eeding Spring, they ail recruit again ; and are ifh’d with frefh Supplies and Verdure: But fitft, thofe which afe loweft and. neareft the Earth, Herbs, ‘and: they thar require a lefler — trams * ! , degree
240 Mifcellanea Curiofa. | degree of Heat to raife the Water with its — Earthy Charge into them: Then the Shrubs — and higher Vegetables in their Turns ; and laft- — ly, the Trees. As the Heat increafes, it grows — too powerful, and hurries the Matter with too — great Rapidity thorough the finer and more — tender Plants : Thefe therefore go off, and de- — cay ; and others that are more hardy and vigo- rous, and require a greater fhare of Heat, fuc- ceed in their Order. By which Mechanilm, © provident Nature furnifhes us with a very vari-— ous and differing Entertainment 5 and what is” beft fuited to each Seafon, all the Year round. | » As the Heat of the feveral Seafons affords us a different Face of Things; fo the feveral di-— fant Climates fhew different Scenes of Na- f comp ai ture, aig Productions of the Hift. Earth, Pag. Eat th “J 4 ee oe ng oe “a 267. & feq. tries yield ordinarily the lar | geft and talleft Trees; and — thofe in too much greater variety than the colder ever do. -Even thofe Piants which are common to both, attain to a much greater Bulk in the Southern than in the Northern Climes, Nay, there are fome Regions fo bleak and chill, that they raife no Vegetables at all to any confidera- ble Size. ‘This we learn from Greenland, from Ifeland, and other Places of like cold Site and Condition. In thefe no Tree ever appears ; and the very Shiubs they afford, are few, little, and low. | Ite CREE Again, in the warmer Climates, and fuch as do furnifh forth Trees and the larger Vegetables, if there happen a remiffion or diminution of the — ufual. Heat, their Produétions will be impeded and diminfhed in proportion. Our ‘late Colder ) | bs Summers
ie Pheer n Wee Se
; ae ‘ _ Mifcellanea Curiofa. | 241 Summers have given us proof enough of this: For though the Heat we have had, was fufficient to_raife the Vegetative Matter into the lower Plants, into our Corns, our Wheat, Barley, Peafe and the like ; and we have had plenty of Straw-berries, Ras-berries, Currans, Goosberries, and the Fruits of fuch other Vegetables as are low and near the arch : Yea, and a moderate {ttore of Cherries, Mulberries, Plumbs, Filberts, and fome others that grow fomewhat at a greater Height ; yet our App'es, our Pears, Walnuts, and the Productions of
the taller * Trees have = * The Dwarf: Apple and
been fewer, and thofe not fo kindly, fo tho- roughly ripen’d, and brought to that PerfeCti- on they were in the for- mer more benign and _ their warm Seafons.Nay, even the lower Fruits and Grains have had fome fhare in the com-
Pear-trees have fucceeded better. And indeed in Trees of the fame kind, thofe tbat keep clofeft to the Earth alwys produce the moft and beft Fruit. For which Rea- fon’ tis thit the Gardiners check and reftrain the Growth of better Pruit- trees, and prevent their running up to too great & Height. .
‘mon Calamity ; and fal- len fhort both in Number and Goodnefs of what _ the hotter and kinder Seafons were won’t to fhew us. As toour Grapes, Abricots, Peaches, Ne- Garens, and Figs, being tranfplanted hither out _of hotte: Climes, ’tis the lefs wonder we have of _ late had fo general a Failure of them. Nor is it the Sun, or the ordinary emiffion of _the Subterranean Heat only, that promotes Ve- getation ; but any other indifferently, according to its Power and Degree : This we are taught by our Stoves, hot Beds, and the like. All “aes J R eu
242 Mifcellanea Curiofa.
Heat is of like kind; and where-ever is the fame Caufe, there will be conftantly the fame Effeat. There’s a Procedure in every part of Nature, that is perfectly regular and geometrical, if we | ean but find it out ; and the further our Searches carry us, the more fhall we have occafion to admire this, and the better twill compenfate our Induttry: * ty?
ot
Ao Fis et CC
"eS t aR ie > ae
| Mifeellanea Curia. 943
An Account of the Meafure of the _ thicknefs of Gold upon Gilt Wire ; together. with Demonftration of
the exceeding Minutenefs of the
| Atom i -or’con (tituent’ Particles of
"Gold's as it was read before the
~ fion.
-: Royal Society, ‘by E. Halley.
VAT HAT are the conttituene, Parts of Mars iW); ¥, ter, and how: there. comes to be fo great a diverfity in-the weight of Bodies, to all ap- pearance. equally folid ;and. denfes) fuch as are Gold. and Gla, (whole fpecifick .Gravities are nearly-as 7, toi). {eems.a.very.hard Queltion to — thofe that fhall rightly confider it :. For fromun-
doubted Experiment, | Gravity. is in, all Bodies proportionable..to: the Quantity of . Matter in. each; und-there is, no, fuch thing as a Propen- -of ,fome.,more.,), others. lefs;. towards «Hf
_ Earth’s Center 3, fince the Impediment of the
Air being removed, all Bodies defcend, be they
— pever fo loofe, or. compact in Texture,.with e:
- qual Velocity... It follows therefore, That there fis. 7 pee asmuch Matter in Gold, as in a picce
of Gf,
of the fame Magnitude ;, and confe-
quently, that av leaft fix. parts of feven: in the
Bulk of Glafs, muft be Pore-or Vacuity: ‘This
-fome Favourers of the Atomical, Philofophy have
endeavoured to, folve,. by. fuppofing, the primary —— Ra or
244 Mifcellanea Curiofa. or conftituent Atoms of Gold to be much larger than thofé of other Bodies, and conféquently the Pores fewer ; whereas in other Bodies, the great ~ multitude of the interfperfed Vacuities does dimi- nif their "Weishts. °) °°" "9 (oe > Being defirous to examine. this Notion ‘of: the Magnitude of Atoms of Gold, I bethought .my felf of the extreme Dudility of that Metal,-which. is feen in the beating of it into Leaf, and above all in the drawing fine, Gilt-wire, , by. means whereof, I believed I might moft exaétly obtain
the true thicknefs of the Coat of‘ Gold, “that ’ ap-
pears, even with the Microfcope, fo: wellsto re- prefent Gold it felf, that not the leaft point of Silver appears through it. In order to this, Lin- form’d my felf among’ the Wire-drawers, what Gold they. us'd to their’ Silver > and “they told me, That the very beft double Gilt Wire’ was ~ made out of Cylindrick’ Ingots, ‘4’ Inches* in ‘Cir! cumference, and 28 Inches Jong, which’ weigh’ 16 Pounds Troy ; ‘on thefe-they beftow 4 Ounces of Gold, that is, to every 48 Ounces of Silver one of Gold ; and that two Yards’ of ‘the fuper- fine Wire weighs a Grain. Hence’ at firft’ fight it appear’d, that the length of 98 Yards is in weight 49 Grains, and that a fingle Grain of
Gold covers the faid 98 Yards, and that the
tooooth part of a Grain is above $ of an Inch
long; which yet may be adtually divided into” 10, and fo the rooocoth part ofa Grain of Gold be vifible without’a Microféope. “But be- ing defirous to compute the thicknefs of the Skin
of Gold, by means of the fpecifick Grayities of _
the Metals, viz. Silverro$, and Gold 183, I found the Diameter of fuch’ Wire the s3z° part of an Inch, and its Circumference the x35 part 5 but ¥ 5 lee i a ; the
bo RN Sie, | if 4
}
ney = on
Mifcellanea Curiofa. 245 the Gold in thicknefs not to exceed the ryre5q part of aa Inch ; whence it may be concluded, that the Cube of the hundredth part of an Inch would contain above 24.3 2000000, (or the Cu;be of 1345) ‘of fuch Atoms. And it may likew fe be marvelled at, that Gold being ftretcht to fo great a degree, as is here demonftrated, fhould yet fhew it felf of fo even and united a Texture, _ as not to let the white Colour of the Silver un-
der it appear through any the leaft Pores; which _ argues, that even in this exceeding thinnefs very many of thofe Atoms may ftill lie one over the other :- Which isa Confideration may merit the _ Thoughts of this Honourable Society, as tending to examine that renowned Atomical Doétrine, — which has of late much obtain’d among the Learned. a ee
ee
OE IEE REET Re ROME gS EDD a GPCR es i a Bh Me a wen i ep Amnnd
246 i Mifcellanea Curiofa.
eee
An Account of the feveral Species of Infinite Quantity, and of the Proportions they bear one to the other ; as it was read before the
Royal Society, by E. Halley. _
Tt HAT all:Magnitudes. infinitely gteat, or : fuch as exceed any affignable Quantity, are equal among themfelves, though it be vul- garly received for a Maxim, is not yet fo coms "mon as it is erroneous; and the Reafon of ‘the miftake feems to be, That the Mind of Man, coming .to contemplate the Extenfions of what exceeds the bounds of its Capacity, and of which the very Idea does include a Negation of Li- mits ; it comes to pafs that we we acquiefce ge- nerally, and it fuffices to fay fuch a Quantity is infinite. :
- But.if we. come..more. .nearly. to-examiae--this Notion, we fhall find, that there are really be- fides infinite Length and infinite Area, no lefs — than three feveral forts of infinite Solidity; all of which are Quantitates fui generis, having no more relation or proportion the one to the other, than a Line to a Plane, or a Plane to a Solid, or a Finite to an Infinite : But that among them- felves, each of thofe Species of Infinites are in iven Proportions, is what now intend to make plain, if poffible. i
But
\
Mifcellanea Curiofa. 24.7
Bat firft, infinite Length, or a Line infinitely Jong, is to be confidered either as beginning at a Point, and fo infinitely extended one way, or elfe both ways from the fame Point 5 in which café the one, which isa beginning Infinity, is the one half of the whole, which is the Summ of the beginning and ceafing Infinity ; or, as I may fay, of Infinity, 2 parte ante, and 2 parte poft : Which is analogus to Eternity in Time or Du- ration, in which there is always as much to fol- low as is paft, from any point or moment of Time : Nor doth the Addition or SubduGtion of finite Length or Space of time alter the cafe either in Infinity or Eternity, fince both the one
or the other cannot be any part of the whole.
' -As to infinite Surface or Area, any right Line, infinitely extended both ways on aminfinite Plane, does divide thar infinite Plane-into equal Parts ; the one tathe right, and the other to the left of the faid Line: But if from any Point in fuch a Plane, two right Lines be infinitely extended, fo as to make an Angle, the infinite Area, inter- cepted between thofe infinite right Lines, is to the whole infinite Plane, as the Arch of a Cir- cle, on the Point of Concourfe of thofe Lines, as a Centre, intereepted between the. faid Lines, 4s to the Circumference of the Circle ; or as the Degrees of the Angle to the 360 Degrees of a Circle. For Example, two right Lines meeting ata right Angle do include, on an infinite Plane, a quarter part of the whole infinite Area of {uch moPiane.
But if fo be, two parallel infinite Lines be fup- pofed drawn on fuch an infinite Plane, the Area intercepted between them will be likewife inf- nite ; but at the fame time will be infinitely lefs, R 4 than
SS
248 Mifcellanea Curiofa. ‘than that Space which is intercepted between two
_ infinite Lines that are inclined, though with ne- ver fo fmall an Angle; for that in the one Cafe,
; bs So eS ae Per Yet ee
the given:finite diftance cf the parallel Lines di-
minifhes the Infinity in one Degree of Dimen-
_fion; whereas in a Sector, there is Infinity in —
both Dimenfions; and confequently, the Quan- tities are the one infinitely greater than the other, and there is.no proportion between them.
From the fame Confideration arife the Three
-feveral Species of infinite Space or Solidity, as _ - has been faid ; for a Parallelepepide, ora Cylin- —
der, infinitely long, is greater than any finite Magnitude how great foever ; and all fuch So- lids, f{uppofed to be formed on given Bafes, are
as thofe Bafes, in proportion to one another. —
But if two of thefe three Dimenfions are wan- ting, as in the Space intercepted between two pirallel Planes infinitely extended, and at a finite
diftance ; or with infinite Length and Breadth, |
with a finite Thicknefs ; All fuch Solids fhall be
as the given finite diftances one to another: But thefe Quantities, though infinitely greater than the other, are yet infinitely lefs than any of
thofe, wherein all the three Dimenfions are infi-
nite. Such are the Spaces intercepted between t.vo inclined Planes infinitely extended ; the Space
intercepted by the Surface of a Cone,~or the fides
-of a Pyramid likewife infinitely continued, &e: of all which notwithftanding, the Proportions one to another, and to the. 73 mv, or vaft Abyfs of infinite Space (wherein is the Locus of all
things that are or can be; or to the Solid of in-
finite Length, Breadth, and Thicknefs, taken all -manner of ways) are eafily affignable. For the Space between two Planes, is to the whole, as
the
BEAN ans
——— Mifcellanea Curtofa. 249 _the Angle of thofe Planes to the 260 Degrees of the Circle. As for Cones and Pyramids, they are as the Spherical Surface, intercepted by them, is to the Surface of the Sphere ; and therefore Cones are as the verfed Sines of half their An- gles, to the Diameter of the Circle: Thefe three ‘forts of infinite Quantity are analogous toa Line, Surface and Solid, and after the fame manner , cannot be compared, or have any proportion the “one to the other. — : - Befides thefe, there are feveral other. Species of infinite Quantity, arifing from the Contemplation of Curves, and their Afymptotes; which, by reafon of ‘the difficulty of the Subje@, cannot be made fo plain to moft Readers : But what has been already faid, may be fufficient to evince what we undertook to explain.
*
250 Mifiellanea Curiofa. 4
> Oa eapeinreniak
An Account of Dr. Robert Hook’s Lnvention of the Marine Baro- meter, with its Defcription and Ujes ; publifbed by order of the Royal Society, by K. Halley, R.
Ince it was found that the Torricelian Tubes commonly call’'d the Mercurial Barometers by the rifing and falling of the Quick-filver therein, doth prefage the Changes of the Air, in relation to fair and foul Weather ; upon feveral Years Obfervation of it, it has been proved and adjufted for that purpofe by Dr. Ro- bert Hook; and there have been by him ma-— ny attempts to improve the Inftrument, and render the Minute Divifions on the Scale thereof more fenfible. He alfo judging that it might be of great ufe at Sea, contrived fe- veral ways to make it ferviceable on Board of — Ship ; one of which he explain’d to the Royal Society at their Weekly Meeting in Grefham Col- lege, Fanuary 2 1663. Since which time he hath further cultivated the Invention, and fome Years ago produced before the faid Soci- ety, the Inftrument I am now ‘to defcribe, which for its fubtilty and ufefulnefs, feemeth to
Maifeellanea Curtofa. 251 to furpafs all other performances of the like Na- ture. i ait Till fuch time as the Author’s prefent Indi- fpofition will give him leave to beftow freely his Thoughts on this Subject upon the Publick, it is the Opinion of the Society, that fuch an Aceount be given of this Contrivance, as may render it known, and recommend it to the Ma- riners ufe, for which it was principally in- The Mercurial Barometer requiring a perpen- dicular Pofture, and the Quick-filver vibrating
therein with great Violence upon any Agitation, i3 therefore uncapable of being ufed at Sea (tho’ it hath lately been contrived to be made porta-
ble), fo it remain’d to find out fome other Pria- . ciple, wherein the Pofition of the Inftrument was not fo indifpenfably neceflary : For this, all thofe that ufe the Sea are obliged to the great facility Dr. Hook has always fhewn, in apply- ing Philofophical Experiments to their proper ES ll eli It is about forty Years fince, that the Ther- ‘mometers Of Robert de Fluéibus, depending on
‘the Dilatation and Contraétion of included Air
‘by Heat and Cold, have been difufed, upon difCovery that the Airs preffure is unequal ; that inequality mixing it felf with the Effects of the warmth of the Air in that Inftrument. And inftead thereof was fubftiruted the feal’d Thermometer , ‘including Spirit of Wine (firlt brought into England, out of Italy, by Sir Ro-
bert Southwell) as a proper Standard of the temper of the Air, in relation to Fleat and
Cold; that Aitherial Spirit being of all the Xnown Liquors the moft fufceptible of Dilata-
: tion
%
252 Mifceilanea Curiofa,.
tion and Contraction, efpecially | with a. mode- rate degree of either Heat or Cold) Now this being allow’d as a Standard, ..and, the other
- Thermometer that includes Air, being gradua-
ted with the fame Divifions, fo, as at thetime when the Air was included, to agree with the Spirit-Thermometer in all the degrees of Heat and Cold, noting at the fame time the precife height of the Mercury in.the common Barometers : It will readily be underftood, that whenfoever thefe two Thermometers {hall agree, the pref- fure of the Air isthe fame it was, when the Air was included, and the Inftrument gradua- ted: That if in the Air-Thermometer the Li- quor ftand higher than the Divifion marked thereon, correfponding with that on the Spi- riteglafs, it is an indication that there is a greater preflure of the Air at that time, than when the Inftrument was graduated. And the contrary isto be concluded, when the Air-glafs ftands lower than the Spirit, w/z. that then the
Air is fo much lighter, and the Quick filver, in
the ordinary Barometer lower than at the faid time of Graduation. ee ae
And the Spaces anfwering to an Inch of Mer- cury,. will be more or lefs; according to the guantity of -Air fo included, and the {mallnefs of the Glafs Cane, in which the Liquor: rifes. and falls, and may be augmented almoit in a- ny proportion, under that of the Specifick: Gra- vity. of the Liquor of the Thermometer to Mer, cury.. So.as to have a Foot or, more for an: Inch of Mercury, which is another great con- venience, cree | 7
1 ie ee
Mifcellanea Curiofa. 2153 ~ It has been obferved -by fome, that in long keeping this Inftrument, the Air included either’ finds a means to efcape, or depofites fome Va- pours mixt with it, or elfe for fome other caufe. becomes lefs Elaftick, whereby, in proces of time, ‘it gives the height of the Mercury fomee what greater than it ought ; but this, if it fhould happen in fome of them, hinders not the uféful- nels thereof, for that it may at any time very eafily be corrected by Experiment, and the ri- fing and falling thereof are the things- chiefly remarkable in it, the juft height being barely a Peek ag te < M NT aA | ~'In thefe Parts of the World, long Experi- ence has told us} thar the rifing of the Mer- eury forebodes fair Weather ‘after foul, and an Eafterly or Northerly Wind ; and that the fal- ling’ thereof, on the-contrary, fignifies Souther-_ ly or Welterly Winds, with Rain, or ftormy: Winds, or both; which latrer it is of much mMore confequence to provide againft at Sea than at’ Land ;' and in a Storm, the Mercury begin- ning to rifé isa fure fign that it begins to abate, as has been experienced in high Latitudes, both to the Northwards and Southwards of the AR- _ The Form of this Inftrument is fhown in the Cut, by Tab. 4. Fig. 1, wherein,
_ A Breprefents the Spirit-Thermometer, gradua- ted from 0; or the freezing Point, through all the poflible'deprees of the Heat or Cold of the. Air, at leaft’in' thefe'Climates. ey CD, is the Air-Thermometer, graduated after. the fame manner with the like Degrees, |
E F,
- common Barometers.
254 Mifcellanca. Curiofa. He 7
Gy a Hand ftanding on toa Pale absabal height of the Mercury. thereon, as. it_ was. ‘when the Inftrument was graduated, as fuppofe here at. 29% Inches situ ai aeicaall
"LM, a Wire on which the Plate EF, flips up. and down, parallel to the Cane of the Thermo- meter CD. < jsbecke tan eae Ocal
‘K, any -Poine at which the, Spirit Mands. at, the time of Obfervation ; fuppofe at 38; on) the Spirit-Thermometer 5 Slide the Plate. EF. till the Hand G ftand at 38 on the Air-Ther-s mometer, and if the Liquor therein fland at, 28 likewife, then 1s the preffure of, .the,, Airy the fame as at the time of Graduation, vig) 2.9, 5 3 but if it ftand. higher, as. at. 30,/ at..1.5) then is the preflure of the Air greater 5), and’ the divifion on, the fliding Plate againit . che, Liquor, fhews the prefent height of the .Mer-. cmy to be twenty nine Inches feven;,Tenths, And this may fuffice as; to the manner of ufing, ite. Png gigoe baa. eas snot oct a { had one of thefe Barometers with me. in, my late Southern Voyage, and it never. fail- ed to prognoftick and, give early notice. of all, the bad. Weather we -had,. fo, that) I, depended thereon, and made provifion accordingly, 5 and; fom. my own. Experience I conclude; that..a more ufeful Contrivance) hath not), for this long time been offer for-- the. benefit of INa-
Vigation. _
Thefe
Mifeellanea Guriofa. 255,
_ Thefé Inftruments are made according to the Direétion of Dr. Hook, by Mr. Henry Hunt, Ope- rator to the Royal Society, who will furnifh any Gentlemen with them, and give them DireGtions low. to ufe them. sh mei te
ETS PREP Se SOD ae ee ; ny ae ’ |
256 Mifiellanea Curiofa. =
A Difcourfe concerning the Propor- tional Heat of the Sun in all La- titudes, with the Method of col- lefting the fame; as it was read before the Royal Society, in one of their late Meetings. By}. Hal-—
i ee having lately arifen fome Difcourfe — about that part of the Heat of Wea- ther, fimply produced by the Aéction of the Sun; and I having affirmed, that if. that were confidered, as the only Caufe of the Heat of the Weather, I faw no Reafon, but : that under the Pole the folftitical. Day ought — to be as hot as it is under the Aiquinoctial, when the Sun comes vertical, or over the Zenith: For this Reafon, that for all the 24 Hours of that Day under the Pole, the Sun’s Beams are inclined to the Horizon, with an- Angle of 233 Degrees; and under the Aiqui-— noétial, though he come vertical, yet he fhines — no moré than 12 Hours; and is again 12. Hours abfent ; and that for 3 Hours 8 Minutes of that 12 Hours, he is not fo much elevated as under the Pole; fo that he is not 9 of the whole 24, higher than tis there, and is 15 Hours lower. Now the fimple Aétion of the Sun is, as all other Impulfes or Stroaks, nS : or
%
ee eee
a sk cM a cde
Ne a eS pm Oe eee me ‘ @ a Curio
Mifeellan yar. ‘eanz ~or lef forceable, according to the Sinus of the Angle of Incidence, or to the Perpendicular let fall on the Plain, whence the vertical Ray (bes ing that of the greateft Heat,) being put Redius, — the force of we a on the Horizontal Surface of the Earth willbe to that, as the Sinus of the Sun’s Altitude: at any other time. This being allow’d for. true, it will then follow, that the time of the continuance of the Sun’s fhining be- ing taken for a Bafis, and the Sines of the Sun’s Altitudes ereted thereon.as Perpendiculars, and a Curve drawn through the Extremities of thofe Perpendiculars,* the Area comprehended fhall be proportionate to the Collection of the Heat of all the Beams of the Sun in that fpace of time. Hence it will follaw, thar under the ’ Po'e the Collection of all the Heat of a tropie cal Day, is proportionate to a ReCtangle of the Sine: of 222 gr. into 24 Hours, or the Cir cumference of a Circle ; that is, the Sine of 233 - gr. being nearly 4, Tenths of Radius ; as ¥5 into _ 32 Hours. On the Polar Heat is equal to that of the Sun containing 12 Hours above the Horizon, at $3 gr height, than which the Sun is not: 5’ Hours more elevated under the qui- moctials 4 — 34:13 sg - But that this Matter may the better be un- derftood, I have exemplified ic by a Scheme, (Tab. 4. Fig. 2.) wherein the 4rea XG HH, is equal to ithe Area of all the Sines of the Sun’s Altitude under the Aiquinoétial, ereéted on the tefpective Hours from Sun-rife to the Zenith ; and the Area & HH & isin the fame propor- tion to the Heat of the fame 6 Hours under the Pole on the Topical Day; and OH HQ, is proportional to the collected Heat of 14 oat Hours,
358 AMifcellanea Curiofa.. —
' Hours, or half a Day under the Pole, which {pace © H HQ, 1s vifibly greater than the other Area H XG H, by as much as the Area HGQ
is greater than the Area’ X G © 3) which, sthat sit
is fo, is vifible to fight, by a great: excefs 5 and: fo much in proportion does the Heat of: the 2.4. Hours Sun-fhine under the. Pole, exceéd that of the 12> Hours under the AiquinoGtial: Whence, Cateris paribus, it is reafonable to. coriclude, that were the Sun: perpetually under: the Tropick, the Pole would be at leaft as wafm, as itis now. — unddr the Lineite felf sce sd cucwh awerh Satthee
. Buc whereas the Nature of Heat is to remain in the Subje&, after the Caufe that heated is re- moved, and particularly in the Air; under the Aiquinoétial, the 12 Hours abfence of the Sun — does very little ftill the Motion» impreffed by
the paft AGtion.of his: Rays, wherein Heat con- fifts, before he arife again : But ‘under the Pole the long abfence of the Sun for 6 Months, where: _ in the extremity of Cold does obtain, has.fo — chill'd the Air, that it is as it were frozen, and cannot, before: the Sun shas got far towards it, be any way fenfible: of his: prefencey ‘his: Beams. being obftruéted by. thick Clouds, and perpe- tual Fogs and Miits, and by that Atmofphere _ of Cold, as the late, Honourable Mr. Boyle was pleafed to term it, proceeding from the ever- lafting Ice, which in immenfe Quantities .does chill the ‘Neighbouring Air, and which the too foon retreat of the Sun Jeaves -unthawed, to en- créafe again, during- the long Wintet that fol- lows ven interval of Summer. But the differing Degrees of Heat and Cold, in differ- ing Places, depend: in ‘great meafure upon the Accidents of the Neighbourhood of high Moun-
oy Rip denice a ae ea ee
Mifcellanea Curiofa. 259 tains, whofe height exceedingly chills the Air ° brought by the Winds over them; and of the Nature of the Soil, which varioufly retains the Heat, particularly the Sandy, which in Africa, Arabia, and generally where fuch Sandy Defarts are found, do make the Heat of the Summer in» credible to thofe that have not felt ir. |
In the profecution of this firft Thought, J have folved the Problem generally, viz. to give the proportional Degree of Heat, or the Suth of all the Sines of the Sun’s Altitude, while he is above the Horizon in any oblique Sphere, by reducing it to the finding of the Curve Sur- face of a Cylindrick Hoof, or of a given part thereof. | |
Now this Problem is nct of that difficulty as — appears at firt fight, for in Tab. 4. Fiz. 3. let the Cylinder ABCD be cut obliquely with the Eilipfe BDI, and by the Center thereof H, de- feribe the Circle IAILM ; I fay, the Curve Sur- face IKLB is equal to the Rectangle of IK ‘and BL, or of HK and 2 BL or BC: And if there be fuppofed another Circle, as NQPO, cutting the faid Ellipfe in the Points P,; Q_; draw PS, ‘OR, parallel to the Cylinders Axe, till they meet with the aforefaid Circle IKILM in the Points R,;-S, and draw the Lines RTS, QVP bife&ted in T and V. I fay again, that the Curve Surface RMSQDP is equal to the Re» angle of BL or MD and RS, or of 2 BL or AD and ST’ or VP; ‘and the Curve Surface QNPD is equal to RS x MD- the Arch RMS x SP, or the Arch MS x 2 SP: OF ir fs equal to the Surface RMSQDP, fubftraGing the Surface RMSQNP. So likewife the Curve Surface QBPO is equal to the Sum of the Sur- “p S 2 face
han, i . SE Oe? SS Se oe Se PEE Fe 8 a 7 | ie > he ig = pi vin ie ig Nae eaieie) Ay
‘ ae"
260 =Mifcellanea Curiofa. ~ face RMSQDP, or RS x MD, and of the Sur- face RLSQOP, or the Arch LS x 2 SP.
This is the moft eafily demonftrated from the Confideration, ‘That the Cylindrick Surface IKLB. is to the in{crib’d Spherical Surface IKLE, cither in the whole, or in its Analogous Parts, as the tangent BL is to the Arch EL, and from the Demonftrations of Archimedes de Sphara & ‘Cylindroy Lib. 1. Prop. XXX, and XXXVII, XXXIIX. which I fhall not repeat here, but leave the Rea- der the pleafure of examining it himfelf; nor will it be amifs to confult Dr. Barrow’s Learned Lectures on that Book, Publifh’d at London, Anno 1684, viz. Probl. 1x. and the Corollaries thereof. .
Now to reduce our Cafe of the Sum of all the Sines of the Sun’s Altitude in a given Declina- - tion and Latitude to the aforefaid Problem, Jet us confider (Tab. 4. Fig.'4.) which is the Anae lemma projected on the Plain of the Mersdian, Z the Zenith, P the Pole, HH the Horizon, wz x the Aiquinoctial, & %, vp vp the two Tropicks, & Ithe Sine of the Meridian Altitude | in & ; and equal thereto, but perpendicular to the Tropick, erect % 1, and draw the Line "T 1 interfeting the Horizon in T, and the Hour Circle of 6, in the Point 4, and 6 4 fhall - be equal to 6R, or to the Sine of the Altitude at 6 : And the like for any other Point in the Tropick, ere€ting a Perpendicular thereat, terminated by the Line TI’ 1: Through the Point 4 draw the Line | 4y 5> 7 parallel to the Tropick, and reprefenting a Circle equal thereto; then fhall the Tropick o% % in Fig. 4. anfwer to the Circle NOPQ, in Fig.3. the Circle 4, 5, 7, fhall anfwer the Circle IKLM, T 4.1 fhall anfwer to the Elliptick Segment QIBKP, 6R or 6 4 fhall anfwer to
>
BORE a ead 9 Og ip bee tats 5 in
| Mifcellanea Curiofa. 261 SP, and 4 1 to BL, andthe Arch & T, to the Arch LS, being the femidiurnal Arch in that La- titude and Declination ; the Sine whereof, tho” not expreffible in Fig. 4. mutt be conceived as
Analogous to the Line TS or UP in Fig. 3.
The Relation between thefe two Figures be- ing well underftood, it will follow from what precedes, That, the fum of the Sines of the Meri-
‘dian Altitudes of the Sun in the two Tropicks, (and the like for any two oppofite Parallels) being multi~ plied by the Sine of the femidiurnal Arch, will give an Area Analogous to the Curve Surface’ RIMSQDP; and thereto adding in Summer, or- Subftratting in Winter, the Produtt of the length of the femidiurnal Arch, (taken according te-Van Geulen’s Numbers) into the difference of the above~ faid Sines of the Meridian Altitude: The fum in one cafe, and difference in another, fhall be as the Aggregate of all the Sines of the Sun’s Altitude, during his appearance above the Horizon 3 and con-
— fequently of all his Heat and A€tion on the Plain of | the Horizon in the propofed Day. And this may alfo be extended to the parts of the fame Day ; for if the aforefaid Sum of the Sines of the Meri-
dian Altitudes, be multiplied by half the Sum of the Sines of the Sun’s Horary diftance from Noon, when the Times are before and af- ter Noon; or by half their difference, when | both are on the fame fide of the Meridian ; and-
thereto in Summer, or therefrom in Winter ,. be added or fubftrated the Product of half the Arch anfwerable to the propofed interval of Time, into the difference of the Sines of Meridian Altie | tudes, the Sum in one cafe and Difference in the other, fhall be proportional to all the Action of the Sun during that fpace of time. ba S I fore-
462 Mifcellanea. Cuviofa.
I fore-fee it will be Objected, that I take the Radius of my Circle on which I ere& my Per- pendiculars always the fame, whereas the Paral- _ lels of Declination are unequal ; ‘but to this 1 anfwer, That our faid Circular Bafes ought not to be Analogous to the Parallels, ~ but to the Times of Revolution, which are Amat in all of them.
It may perhaps be etal to give an whites
the Computation of this Rule, which may feem difficult to fome. Let the Solfticical Heat in & and w be required at age? ee ate by 3" te ah uke 2
380-2'8 Co-Lat. . Diff. Afcen : 3300-1" 1. | 23, 30 Decl. © _ | Arch. Semid, lin 123-EL. 61-58 Sinus= ,8826 4] Ar.Sem.byb. 56-49.8,638923 14-58 Sinus 268267 Arch.aftivimenfura2,t4995$
ee
: Summa 1,140931|4re. byb. menfura. 991683, Diff. 624417
Then t 5140931 in JR em + 624417 3 in vi 1499557 12.9734 And, ERR in $36528. —2eq4atz in OT ORE F250 Teh. aN ito:
ee ae 2529734. Mell be as he opt Summers Day Heat, and 0,32895.,as the AGion of the Sun in the Day. of the Winter Solftice. - ,
After: this ‘manner I computed hy following Table for every tenth Degree. of Latitude, to the ‘Equinodtial and Tropical Sun, by which an Eftimate may be made of the intermedi ate
Rae
Lat.
_ Mifeellanea Curiofa. | 263
ies he soe = Suain |
yar , +i : 20290 0 5 | fp 21737 4° 22651 23048 | 5 P22G08 Pe S768" > | 23773 1075" fa 24673 |. 10; Of 25055. bas
” Thole ey ‘ache ‘tore of the Kavli! 6F ha Problem, as to the Geometry thereof, would do well to compare the XIII. Prop. Cap. V. of the _ Learned Treatife, De Calculo Centri Gravitatis, en the Reverend Dr Wailisy Publifhed Anno
70. i
Oe this Rule there follow Rien Corollaries ! worth Note: AsI. That the Aiquinogtial Heat, when the Sun comes Vertical, is as twice the Square of Radius, which may be propofed ‘46 a Standard to compare with, in all other Cafes. I], That under the A®quinoétial, the Heat is - asthe Sine of the Sun’s Declination. II), That . in the Frigid Zones when the Sun fets not, the Heat is as the Circumference of a Circle into the Sine of the Altitude at 6. And confequently, that in the fame Latitude thefe Aggregates of Warmth, are as the Sines of the Sun’s Declina- tions ; and in the fame Declination of Sol, they
| S 4 are
264 Mifcellanea Cuviofa.
are as the Sines of the Latitude, and generally they are as the Sines of the Latitude into the Sines. of Declination. IV. That the Aiquinoétial Days Heat is every where as the Co-fine of the’ Lati- tude. V. In all places where the Sun fets, the difference between the Summer and Winter Heats, — when the Declinations are contrary, is equal to a Circlé into the~Sine of the Altitude ar fix in the Summer Parallel, and confequently thofe dif- Ferences are as the Sines of Latitude into, or multiplied by the Sines of Declination. VI. From the ‘Table I have added, it appears, that the — Tropical Sun under the Aiquinoctial, has, of all — others, the: Jeaft. Force. Under the Pole it is greater than any. other Days Heat whatfoever, being to that of the Aiquinoétial as 5 to 4.
' From the Table and thefe Corollaries may a general Idea be conceived of the Sum of all the Aétions of the Sun in the whole Year, and that part‘of the Heat that arifes fimply from the Pree fence of the Sun be brought to a Geometrical Certainty: And if the like could be performed for €old ; which is fomething elfe than the bare Abfence of the Sun, as appears by many Inftan- es, we might hope to bring what relates to this part of Meteorology to a perfect Theory. 5
Con-
meee | -— Mifeellanea Curiofa, 965
Cree RS ne are
Concerning the Diftance of the Fiz’d Stars. By the Honourable Fran- ~ tis Roberts, E/g, S$. RS.
| HE Ancient Aftronomers, who had no a other way of computing the Diftances of the Heavenly Bodies, but by their Parallax to the Semi-diameter of the Earth; and. being never able to. difcover any in the fix’d Stars, did from thence rightly enough infer, that their Diftance ‘was very great, and much exceeding that of the Planets, but could go no farther otherwife than by uncertain guefs. — ae ay eke » Since the Pythagorean Syftem of the World has been reviv’d by Copernicus, ( and now by all Mathematicians accepted for the true one) there feem’d Ground to imagine that the Dia- meter of the Earth’s Annual Courfe (which, according to our beft Aftronomers, is at leaft 40000 times bigger than the Semi-diameter of the Earth) might give a fenfible Parallax ‘to the fix’d Stars, though the other could not, and thereby determine their Diftance more pre- | TRA laa ' |
_. But though we have a Foundation to build on fo vaftly exceeding that of the Ancients, there are fome Confiderations may make us fufpeé
that even this is not large enough for our pur-
Monfieur @
Te OR Re, a ea , OS SEE Sie Ree 2
266 = Mifcellanea Guriofa.’
Monfieur Hugens (who is very exaé& in is Aftronomical-Obfervations) tells us, he could ne- ver upseban any vifible Magnitude in the fix’d Stats, though. he uféd-Glafles, which: magnified ete Diameter abo ab tisties. ‘8 MS 04 Now, finceinvalh likelyhood the fix’d Stars are Suns, (perhaps ofa different Magnitude) we may as a reafonable Medium prefiume they are gene- ~ rally about the bignefs ih the Sun. :
Let us then (for Example) fuppofé the Dog- Star to be fo. ‘The Diftance from us to'the Sun being about roo times. the Sun’s Diameter. (as is demonftrable from the Sun’s Diameter being 22 Minutes) ‘it is evident, that the Angle under which the Dog-Star is feen in Mr. Hugens’s Tele- fcope, muft be near the fame with the Angle of its Parallax to the Sun’s Diftance, or Semi-dia- meter of the Earth’s Annual Courfé; fo that the Parallax to the whole Diameter, can ‘be but double fuch a quantity, as even to Mr. Hugens’s nice Obfervation is altogether infenfible. =
~~ The Diftance therefore of the fix’d Stars feems
‘
:
hardly within the reach of any of ovr Methods
sa
to détermine ;’ but from what has been laid down,
we may. draw fome Conclufions that will’ mu illuftrate the prodigious vaftnefs of it, © ‘x, Thatthe Diameter of the Earth’s Annual Orb (which contains at leaft’ 160 Millions of Miles) is but-as a Point in comparifon of *it;"at leaft it muft be above Gooo times the Diftance’ of the Sun: For if a Star fhould appear thro” the’ aforefaid ‘Telefcope half a’ Minuce “broad (which isa pretty fenfible Magnitude) the true apparent Diameter would not exceed’ 18° 3d Mi- - nutes, which is lefs than the 6oooth part of the apparent Diameter of the Sun, and spree ee sk aie ih 3 the
ne Nee Ae hae
Des Bae i iat ;
Mifcellanea Guriofa.. 267 the Sun’s Diftance not the Goooth part of the Diftance of the Star. liskie
9, That could we advance towards the Stars gg Parts of the whole Diltance, and have only. TGs ‘Part remaining, the Stars: would ‘appear Tits tle bigger to us than they do -here;\ for they would fhew no otherwife than they do through a Telefcope, which magnifies an Hundred-fold,
~ "3. That at leaft Nine Parts in Ten of the. Space between us and the fix’d Stars, can receive no greater Light from the Sun, of any of the Stars, than what we have from ‘the Stars in a. pment nt bacicield ay "That Light takes up more time in travel. ling from the Stars to us, than we in making. a We-India Voyage (which is ordinarily per- form’d infix Weeks.) That a Sound would not. arrive to us from thence in 50000 Years, nor a ‘Cannon-bullet in a much longer time. This is eafily computed, by allowing (according to Mr. Newton) ‘Ten Minutes for the Journey of Light from the Sun ‘hither, and that a Sound moves
oy
about 1300 Foot ina Second.
a ‘The
C Sithat han ta TET SO Nae a
i Cag O.ra eit P R
The Famous Mr. Ifaac Newton’s Theory of the Moon. 4
HIS Theory which hath been long expeét- — sed by all the true Lovers of 4fronomy, was communicated from Mr. Newton to Dr. Gre-~ gory, Aftronomy Profeffor at Oxford, and by him publifhed in his Ajtron. Elem. Philof. and Geomer.
«336. From whence, as it was lately tranflated into Engl:fh, I thought fit to infertit here. = > -By this Theory, what by all Aftronomers was. thought moft difficult and almoft’ impoffible to, de done, the Excellent Mr. Newton hath now. effected; viz. to determine the Moon’s Place. even in her Quadratures, and all other Parts of her Orbit, befides the Syzygys,’ fo accurately by ‘Calculation, that the Difference between that and her true Place in. the Heavens, fhall fcarce be above two minutes'in her Syzygys, or above three in her Quadratures, and is ufually fo fmall, that ic may well enough be reckon’d only as a Defeé& in the Obfervation. ‘ And this Mr. New-” ton experienced, by comparing it with very ma-_ ny Places of the Moon, obferv’d by Mr. Flam-_ freed, and communicated to him. a The Royal Obfervatory at Greenwich, is to the Weft of the Meridian of Paris, 2 degrees, ‘19 minutes. Of Uraniburgh, 12 degrees, 51 minutes, 30 feconds. And of Gedanum, 18 de-— gees, 48 minutes.
The
righ. ¢. nee
ean Motions of the Sun and Moon, ac- from the Vernal A@quinox at the Meridi- eenwichy 1 make to be as followeth, The laft Day of December 1680, at Noon (Old Stile) the mean Motion of the Sun was 9 Signs, 20 degrees,-34 minutes, 46 feconds. Of the Sun’s Apogeum, was 3S. 7 deg. 22 min. 30 feconds. _ That the mean Motion of the Moon at that time, was 6S. 1 degree, 45 minutes, 45 feconds, And of her Apogee, 8 S. 4 degrees, 2§ minutes, 5 feconds. Of the afcending Node of the Moon’s Orbit, § S.a4deg. 14 min. 25 fetonds, &e. 7 __ And on the laft Day of December, 1700. at Noon, the mean Motion of the Sun was 95. 20 | degrees, 43 minutes, 50 feconds. Of the Sun’s Apogee, 3 S. 7 degiees, 44 minutes, 30 féconds. mean Motion of the Moon was 10 8, 15 de- ) Minutes, 50 feconds. Of the Moon’s 11S. 8 degrees, 18 minutes, 20 {e- nd of her afcending Node, 4.5. 17 de- minutes, 20 feconds Forin 26 Fulie or 7305 Days, the Sun’s Motion is 20 5. 0 degrees, g minutes, 4, feconds. id the Motion of the Sun’s Apogee, 21 mie ju ‘ea conds. } ad Motion of the Moon in the fame time, is ol. 4S. 13 degrees, 24, minutes, 5 fe- And the Motion of the Lunar Apogee, is rol. 3S. 3 degrees, 50 minutes, 15 feconds, the Motion of her Node, 1 Revol. 0'S. fees, FO minutes, 15. feconds. | 8 Motions are accounted from the 1 Equinox: Wherefore if from them re be fubtracted the Receflion or Motion Of the AquinoStial Point, in Antecedentia, durin that fpace, which is 16 minutes, 4® feconds, there : will
i Beiiee ho " eT ie ie é as i ia se
“ri — Mife Lane Gat
will remain the Motions in sell fix’d Stars in 20 Fulian Years; v1 19 Revol. 11 S. 29 degrees, §2 minu conds., Of his Apogee, 4 minutes, 20 feconds. And the Moon’s 267 Revol. 4S, 13 degrees, 17 minutes, 25 feconds. - Of her Apogee, 2 Revol. 2S. 3 degrees, 33 minutes, 5 feconds.» And of the ‘Node of the Moon, 1 Revol. o S. 27 de- grees, 6 minutes, $5 feconds. —
According to this. Computation, the Tropical Year is 265 Days, 5 Hours, 48 Minutes, 57 Se- conds, And the Sydereal Year is 365 Pays, 6 hours g Minutes, r4Seconds. = 5
‘Thefe mean Motions of the Lamnieanied are affected with various masse 3 OF which, pas a4 awe sgn SN
+- There, are the Anduids Equations aforefaid . mean Motions of the §
- Moon, and of | the Apogeels and: “Nod ‘Moon. _ be
The Annual Equation of: the mean | the Sun, depends on the: Eccentrici Earth’s Orbit round .the Sun, which 4s. fuch Parts, as that the Earth's mean. from the Sun fha!l be 1000: Whence the Equation of the Centre 5 and is, ’ 1 degree, 56 minutes, 20 feconds.: —
The greateft Annual Equation « of | mean Motion, is 11 “degrees, 49 fec i her Apogee, 20 minutes, and of her N minutes, 30 feconds. . |
And thefe four Annual. Equat ways mutually proportional on ther: Wherefore when any of - the’ greateft, the other three will alle! be
greatelt ; and when any ‘one leffens, ea | ther
‘Mifcellanea Curiofa. 971
il allo be diminifhed in the fame
innual Equation of the Sun’s. Centre be- g% given, the three, other correfponding. An- nual Equations .will be alfo given; and there- fore a ‘Table of that will ferve for. all. For if the Annual Equation of the Sun’s Centre be taken from thence, for any Time, and be call’d P, and letys P=—Q, OQ+ SFQ=—R,IEP= D, D+ 4ZD=E, and D Gn rade SS 2 F; then fhall the Annual Equation of the Moon’s mean Motion for that time be R, that of the Apogee of the Moon will be E, and that. of the
Node F. iM) ahhiay aris a ie
.. Only obferve here, That if the Equation of the Sun’s Centre be required to be added re then. the Equation of the Moon’s mean Ma- tion muft be. fubtrated, that of her Apogee muft be added, and that of the Node fubdu&- ed, And on the contrary, if the Equation. of the Sun’s - Centre were to be fubducted, the Moon’s Equation mutt be added, the: Equation Lear Apogee fubducted, and that of her Node added. . brihsele cred tae pte ba cching y Paes | | . There 4s alfo. an Equation of ithe Moons. mean
Motion, depending onthe fituation of her Apo- geey in refpet of the Sun ; which is greateft when .the Moon’s Apogee is in, an Odtant
ait. ip ITE: e =,
a the Sun, and is nothing at all when it is the Quadratures or Syzygys, This Equa- mi, When greateft, and the Sun in Perigeo, is Minutes, $6 Seconds, But.if the Sun be in Apogao, it will never be above 3 Minutes. 24 Secounds. At other Diftances of the Sun from the Earth, this Equation, when reateft, is reciprocally as the Cube of fuch Diftance. Bue | when
Pd RP ar 2A ray ae
272 Mifcellanea Curio when the Moon’s Apogee is any where the Offants, this Equation grows lefs, an moftly at the fame diftance between the Earth and Sun, as the Sine of the'double Diftance of the Moon’s Apogee, from the next Quadrature or Syhypy,s to the Raditas?) thie oa Sam
This is to be added to’ the Moon’s Motion, while her Apogee paffes from a Quadrature with the Sun to a Syzygy ; but this is to be fubtraéted from it, while the Apogee moves from the Sy- ayey to the Quadratare, aot on Ae
There is moreover another Equation of the Moon's Motion, which ‘depends en the Afpect of the Nodes of the Moon’s Orbit with the Sun: And this is greateft, when her Nodes are in Oftants to the Sun, and vanifhes quite, when they come to their Quadratures or Sy- zygys. This Equation is proportional to the Sine of the double Diftance’ of the’ Node from the next Syzygy, or Quadrature; and at grea- teft, is but 47 feconds. This muft be added to the Moon’s mean Motion, while the Nodes are pafling from their Syzygys with the Sun, to their Quadratures with him ; but fubtracted while they pafs from the’ Quadratures to the -" Brom the Sun’s true Place, take the e
Py) ees
Mt
re
above fhew’d, the Remainder will be the Annu- al Argument of the faid Apogee. From whence the Eccentricity of the Moon, and the’ fecond Equa- tion of her Apogee may- be computed after ‘the manner of the following (which takes place alfo in the Computation of any other inter mediate Equations. "oh eel ale al
Sa
Let
—- MifcellaneaCuriofa. 273°
a» oid b.vgi Fig. 6. Let-'T reprefent the Earth Ts a Right Line joining the Earth and Sun» - TACB, a Right Line drawn from the Earth
‘to the middle or mean Place of the Moon’s Apo- gee, equated, as above: “Let the Angle SIA be the Annual Argument of the afurefaid Apo- _ gee, T’A the leaft Eccentricity of the Moon’s _ Orbit, TB the greateft.. Biflect AB in G; “ and on the Centre C, with the Diftance AC defcribe a Circle AFB, and make the Angle ~BCF = to thedouble of the Arnual: Argument. _ Draw the Right Line TF, that fhall be ‘the:Ec- centricity of the Moon’s Orbits and the Angle BT'F, is the fecond once of the Moon’s _ Apogee required)! 20
In order to whofe Bert riniirations bet the mean | Diftanae! of the Earth from the Moon, or the _ Semi-diameter of the Moon’s Orbit; be*t00000 3, then fhall its greateft Eccentricity'T B be 667 fuch Parts ; andthe leaft. T A, 433109. that the greateft Equation of the Orbit, om when the Apogee is in the Syzygys, will be 7 degrees, 29. minutes, 30: feconds, or perhaps 7 degrees, ‘4.0 minutes, (for I fufpeét there will be fome Alteration, according to the Pofition of the Apogee in Cancer and Capricorn.) But when it is Quadraté tothe Sun, the greateft Equation az forefaid will be 4 degrees, s7 minutes, 56 fe2 _conds ; ; and the greateft Equation of : the Apo- gee, 12 degrees, 1.5 minutes, 4 feconds, _ © Having front’ thefe.. ‘Principles made a Table of the Equation: ‘of the: Moon's» Apogees:.and: of the’ Eccentricities: of her Orbit. to each: de- gree-of the Annual’ Argument,.. from whence the Eccentricity TF, and the Angle BT F (vige the. fecond andthe) mae Equation of
tne
Pg, a er A RRR
274 Maifcellanea Curiofa. _ the Apogee) may eafily be had for any Time required ; let the Equation thus found be ad- ded to the firft Equated Place of the Moon’s Apogee, if the Annual Argument be lefs than gO degrees, or greater than 18@ degrees, and lefs than 270; atherwife it muft be fubduéted _ from it; and the Sum or Difference fhall
be the Place’ of the Lunar Apogee fécondarily equated ; which being raken from the Moon’s
Place equated a third time, fhall leave the mean Anomaly of the Moon correfponding to any given Time. Moreover, from this mean Anomaly of the Moon, and the before- found Eccentricity of her Orbit, may be found ( by means of a Table of Equations of the Moon’s Centre made to every degree of the mean Anomaly, and fome Eccentricities, (viz. 4.5000, $0000, 55000, 60000, and 65000) the Proftapherefis, or Equation of the Moon’s Cen- tre, asin the common way : And this being taken from the former Semi-circle of the mid- dle Anomaly, and‘added in the latter to the Moon’s Place thus thrice equated, will pro- duce the Place of the Moon a fourth time. equated. , Pea tpinces art eer
‘The greateft Variation of the Moon (2%, that which happens when the Moon is in, an: -
O&ant with the\ Sun) is nearly, reciprocally as the Cube of the Diftance of the Sun from the Earth, Let that be taken 37 minutes, 29 feconds, when the Sun is in Perigeo, and 33 minutes, 40 feconds, when he isi» Apogeo > And Jet the Differences of this Variation in the O@ants be made reciprocally, as the Cubes of the Diftances of the Sun from the Earth ; and fo let a Table be made of the aforefaid Varia-
| tion
Mifcellanea Curiofa. 275 tion of the Moon in her Qétants (or its Lo- garithms ) to every Tenth, Sixth, or Fifth Degree of the mean Anomaly: And for the Variation out of the Oétants, ‘make, as Radi- ‘us to the Sine of the double Diftance of the
_ Moon trom the next Syzygy, ot Quadrature :: fo let the afore-found Variation in the Octant be to the Variation congruous to an other Afpeét ; and this added to the Moon’s
Place before found in the firft and third Qua+ drant (accounting from the Sun) or fub- ducted from it in the fecond and fourth, will give the Moon’s Place equated a fifth time. r __Again, as Radius to the Sine of the Summ of the Diftances of the Moon from the Sun, _and of her Apogee from the Sun’s Apogee (or ‘the Sine of the ExcefS of that Summ above 360 degrees,) :: {0 is 2 minutes, 10 feconds, to a fixth Equation of the Moon’s Place, which
_ mult be fubtracted, if the aforefaid Summ or Ex- cefs be lefs than a Semi-circle ; but added, if it
be greater. Let it be made alfo, as Radius ‘to the Sine of the Moon’s diftance from the Sun:: fo 2 degrees, 20 fecants, toa feventh Equation ; which when the Moon’s Light is in- creafing, add ; but when decreafing, fubtract ; and the Moon’s Place will be equated a {e- venth time, and this is her Place jn her proper 10 a es |
Note here, the Equation thus’ produced by the mean Quantity 2 degrees, 20 feconds, is not always of the fame magnitude ; but is in- creafed and diminifhed, according to the Po- fition of the Lunar Apogee. For if the Moon’s Apogee be in Gastsheion with the a - % Sun’s
\
276 Mifcellanea Curiofa. Sun’s, the aforefaid’ Equation is about 54, fe- conds greater: But when the Apogees are in Oppofition, ’tisabout as much lefs; and it li- brates between its greateft Quantity 2 minutes, 14, feconds, and its leaft, 1 minute, 26 feconds. And this is, when the Lunar Apogee is in Con- — junction, or Oppofition with the Sun’s: But in the Quadratures, the aforefaid Equation is to be leffen’d about s0 feconds, or 1 minute, when the Apogees of the Sun and Moon are in Con- junction ; but if they are in Oppofition, for want ofa fufficient number of Obfervations, I can- not determine, whether it is to be leffen’d or in- -creasd. And even as to the Argument or De- crement of the Equation, 2 minutes, 20 fe- conds, above mentioned, I dare determine no- thing certain, for the fame Reafon, viz. the want. of Obfervations accurately made.” me If the fixth and feventh Equations are aug- mented or diminifhed in a reciprocal Rario of the diftance of the Moon from the Earth ; i. es in a direét Ratio of the Moon’s Horizontal Paral- . lax, they will become more accurate: And this may be readily done, if Tables are firft made to each minute of the faid Parallax, and to every fixth or fifth degree of the Argument of the fixth Equation for the Sixth, as of the diftance of the Moon from theSun, for the Seventh Equaz tion. es Whi. | hi From the Sun’s Place, take the mean motion of the Moon’s afcending Node, equated as above ; the Remainder fhall be the Annual Argument of the Node, whence 4ts fecond Equation may be — computed after the following manner in the pre-— ceding Figure. | AE ORME
Let
pS le ar a
_ Mifcellanea Curiofa. 277
Let T, as before, reprefent the Earih; TS a. Right Line, conjoining the Earth and Sun : Let alfo the. Line —T ACB, be drawn to the Place of the afcending Node of the Moon, as . above equated; and let ST' A be the Annual
- Argument of the Node. Take TA from a
Scale, and let it be to AB:: as 56 to 3, or as 11% tor, Then bifle&t BA in C, andon C as a Centre, with the Diftance C A, de--
_ {cribe a Circle, as AF B, and make the -Angle _ BCF, equal to double the Annual Argument
of the Node before-found: So fhall the Angle
BTF, be the fecond Equation of the afcen-
_ ding Node; which muft be added, when the
Node is pafling from the Quadrature toa Syzy-
_ gy with the Sun; and fubducted, when the Node
_moves from a-Syzygy towards a Quadrature.
aa
_ By which means, the true Place of the Node of
the Lunar Orbit will be gained: Whence from
"Tables made after the common way, the Moon’s _ Latstude, and the Reduétion of her Orbit to the
_ Ecliptick, may be computed, fuppofing the In=
clination of the Moon’s Orbit to the Ecliptick, to be 4, degrees, 59 minutes, 35 feconds, when
_ the Nodes are in Quadrature with the Sun; and
5 degrees, 17 minutes, 20 feconds, when they are in the Syzygys,
And from the Longitude and Latitude thus found, and the given Obliquity of the Ecliptick,
23 degrees, 29 minutes, the Right Afcen- fon and Declination of the Moon will be
found. _.. The Horizontal Parallax of the Moon, when
fhe is in the Syzygys, at a mean diftance from
the Earth, I make to be §7 minutes, 30 {e-
conds ; and her Horary Motion, 33 minutes, 22 i @ ee feconds,
Te»
278 § Miaifcellanea Curiofa. * feconds, 32 thirds; and her apparent Diame- ter 21 minutes, 30 feconds.° But in her Qua- dratures at a mean Diftance from the Earth, I make the Horizontal Parallax of the Moon to be 59 minutes, 40 feconds, her Horary Mo-" tion 32 minutes, 12 feconds, 2 thirds, and her apparent Diameter, 31 minutes, 2 feconds. ‘The Moon in an Oétant to the Sun, and at a mean’ diftance, hath her Centre diftant from the Cen- tre of the Earth about 60 3 of the Earth’s Semi- diameters. - Re eo
The Sun’s Horizontal Parallax I make to be x0 feconds, and its apparent Diameter at a mean diftance from the Earth, I make 32 minutes,
15 feconds. ent ‘The Atmofphere of the Earth, by difper- fing and refracting the Sun’s Light, cafts a Shadow, as if ic were an Opake Body, at leaft - to the height of 40 or 90 Geographical Miles — (by a Geographical Mile, | mean the fixtieth arc of a Degree of a great Circle, on the Earth's Surface.) This Shadow falling upon the Moon in a Lunar Eclipie, makes the Earth’s Shadow be the larger or broader. And to each Mile of the Earth’s Atmofphere, is core refpondent a Second in the Moon’s Disk, fo that the Semi-diameter of the Earth’s fhadow projected upon the Disk of the Moon, is to be increafed about 50 feconds: Or, which is all one, in a Lunar Ecliple, the Horizontal Paral- Jax of the Moon is to be increafed in the Ratio of about 70 to 69. : 2
Thus far the Theory of this Incomparable _ Mathematician. And if we had many Places of the Moon accurately obferv’d, efpecially about her Quadratures, and thefe well ws
mn | pare
\
+ Mifcellanea Curiofa. 279 pard with her Places, at the fame time cal- culated according to this Theory; it would then appear, whether there yet remain any o- ther fenfible Equations ; which when accounted
for, might ferve to improve and enlarge this
Theory. |
wae
280 | Mifcellanea Curiofa. &
An Eftimate of the Degrees of the - Mortality of Mankind, drawn from curious ables of the Births and Funerals at the City of Bre- flaw ; with an Attempt to afcer- tain the Price of Annuities upon — Lives. By Mr. E. Halley’, cosine ROS, Soe set nna te
C Be Contemplation of the Mortality of Mankind, has befides the Moral, its Phyfi- cal and Political Ufes, both which have been fome Years fince moft judicioufly confider’d by the Curious Sir 72/liam Petty, in his Natural and Political Obfervations onthe Bills of Mortality of London, ownd by Captain John Graunt : And fince in a like T'reatife on the Bills of Mor- tality of Dublin. But the Dedu@ion from thofe Bills of Mortality feemed even to their Authors
to be defective: Firft, In that the Number of
the People was wanting. Secondly, That the
Ages of the People dying was:not to be had. — And Laftly, That both London and Dublin, by — reafon of the great and cafual Acceffion of Stran- — ‘gers who die therein, (as appeared in both, by the great Excefs of the Funerals above the Births) rendred them incapable of being Standards for this purpofe ; which requires, if it were poffible, that the People we treat of, fhould not ar all ee oe am be
rN ’ —— 4 \ d 4
I
|
I
a ~ ,
\
t
x
YAY
fo %B6 oe
—
sere
9 ui
Mifcellanea Curiofa. 9281
wer
be changed, but die where they were born, with- out any. adventitious Increafe from Abroad,» or Decay .by Migration elféwhere... anome dt 2p it
aT
Place, as well as of the Country round about ; whence comes that fort of Linnéen we ufually call your Sclefie Linnen ; which is the chief, if “not the only Merchandize of the Place. For thefe Reafons, the People of this City feem _moft proper for a Standard; and the rather, for ‘that the Births do a finall matter exceed the Funerals. ‘The only thing wanting, is the Num- “ber of the whole People, which in fome mea- -fure I have endeavour’d to fupply, by the com- parifon of the Mortality of the People of all Ages, which I fhall from the {aid Bills trace out with all the Accuracy poffible, ,
it
MPS ee kOe
282 Mifcellanea Curiofa, Ie appears that in the Five Years mentioned, viz. from 87 to 91 inclufive, there were born — 6193 Perfons, and buried 5869 5 that is, born per Annum 1228, and buried 1174 ; whence an Increafe of the People may be argued of 64, per Annum, or of about a 20th part, which may perhaps be balanc’d by the Levies for the Empe- rors Setvice in his Wars. But this being con- tingent, and the Births certain, I will fuppofe the People of Breflaw to be increaféd by 1238 Births annually. Of thefe it appears by the fame Tables, that 34.8 do die yearly in the fir Year of their ge, and that but 890 do arrive at a full Year’s Age; and likewife, that 198 do die in the Five Years between 1 and 6 compleat, taken at a Medium; fo that but 692 of the Perfons born do furvive Six whole Years. From this 4ge the Infants being arrived at fome de- gree of Firmnefs, grow lels and lefs Mortal; and it appears, that of the whole People of Breflaw there die yearly, as in the following Ta- ble, wherein the upper Line fhews the Age, and the next under it; the Number of Perfons of that Age dying yearly. _ fess,
ieee
Mifcellanea Curiofa. 283 AS rg 8 eriwaz 28. 34 II, 1166. 55-2 32564362 9+ 8.7.7
36. 42: 45 9-39 54. 55 6 56s G OE C.Gs Fi 7.10 84k rg oe 9 20,42
“qo i 72 77 81 84. go 9614 9+ 11 96 6 .7.3-4.2-51 1.
98 . 99 « 100. Oo. e soy
- And where no Figure is placed over, it is to be underftood of thofe that die between the Ages of the precedent and confequent Co- - From this Table it is evident, that from the Age of 9 to about 25, there does not die above 6 per Annum of each Age, which is much about I per Cent. of thofe that are of thofe Ages : And whereas in the 14, 15, 16, 17 Years, there ap- pear to die much fewer, as.2 and 323 yet that feems rather to be attributed to Chance, as are the other Irregularities in the Series of Ages, which would re&tifie themfelves, were the num- ber of Years much more confiderable, as 20 in- ftead of 5. And by our own Experience in Chrift-Church Hofpital, 1 am inform’d there die of the Young Lads, much about 1 per Cent. per ‘Annum, they being of the aforefaid Ages. From ‘25 to 50, there feem to die from 7 to 8 and 9g per Annum of each Age; and after that to 70, they growing more crafie, though the number be much diminifhed, yet the Mortality increafes, and there are found to die 10 or 11 of each Age per An-
num : From thence the number of the Living be- ing
284 Mifceilanea Curiofa, ing grown very fmall, they gradually decline till there be none left to die 5 as may be feen.at one View in the Table. | 1
- From thefe Confiderations I have form’d the adjoined Table, whofe Ufes are manifold, and give a more juft Idea of the Strate and Condition of Mankind, than any thing yet extant that I know of. It exhibits the Number of People in the City of Breflaw of all Ages, from the Birth to extreme Old Age, and thereby fhews the Chances of Mortality at all Ages, and likewife how to make a certain Eftimate of the Value of Annuities for Lives, which hitherto has been ogly done by an imaginary Valuation. Alfo the Chances that there are that a Perfon of any Age propofed does live to any other Age given; with many more, as I fhall hereafter fhew. ‘This Table does fhew the Number of Perfons that are living in the Age cur- rent annexed thereto, as follows:
bak
Sn cts Ak al
‘
+
142
fp AE Ded Age. {Per- [Age. |Per- [Age. jPer- (Age. Prer- Age. |Per- |Age. |Per- Age. Perfons.
ca (Curt. {fons [C urtifons. \Curt. Ons. |Curt. ffons. {Curt. }fons. (Curt. flons. { a : 3 680] 15 | 628} 22 | 536) 29 | 539) 36 | 498 s ted Se: 67o| 16 4 622) 23° | 579] 39. 53H 37 | 474 4g 42.70 Si 2: 661] 17 | 616) 24 | 573] 32 | 523/38 | 463) 56 2964 22 a 18 | GTO) 25 | SO7, 3% | SIS] 39° | 404) - og 3604 ee “1g | 604, 26 | 560} 33 5071 40 | 445 42, ©3708 Nl 6 $981 27 | $531 34 | 499/40 | 436). 49 °° 2709 | zo 392] 28 | $46) 35° 4 490) 42 1427). 6G 104 § Age. Age. [Pet- Gee Per- |Age. |Per- |Age. {Pere} 63 1694. = | Curt. fons. |Curt. [fons.-|Curt. fons.| 9g 1204 S| 43 bE 202) 72 7 131) 78. 58 77 69% a 44.” 65 192] 72, | 220) 79 49) 84 253 = 4. 45 “€6 | 182] 73 | BOO] 80 | 4H doo 107 S | 46 67 | 1721 74 | ..98) 8t | 34/—— ba 68 | 162| 75 | 88] 82 28] 24000 {4s 69 | x32 76 "| 78) 83. | 23) 9. 7 68 20} -Sum Total.
Thus
ae ST AS Oe eG 42 Se N Ne
286 Mifcellanea Curiofa. Thus it appears, that the whole People of - Breflaw does confift of 34000 Souls, being the - Sum Total of the Perfons of all Ages in the Table : The firft ufe hereof is. to fhew the Pro- portion of Mew able to bear rms in any Multi- tude, which are thofe between 18 and 56, ra- ther than 16 and 60; the one being generally too weak to bear the Fatigues of War, and the Weight of Arms ; and the other too crafie and infirm from Age, notwithftanding particular In- ftances to the contrary. Under 18 from the Table, are found in this City 11999 Perfons, 3950 above 56, which together make 15947. fo that the Refidue to 34.000 being 18053, are. Perfons between thofe Ages. At leat one half thereof are Males, or go27: So that the whole Force this City can raife of Fencible Men, as the Scotch call them, is about gooo, or +7, or fome- what more than a quarter of the Number of Souls ; which may parhaps pafs for a Rule for all other places. i The Second Wfe of this Table, is, to fhew the differing degrees of Mortality, or rather Vitali ty, in all Ages ; for if the Number of Perfons of any 4ge remaining after one Year, be divided by the difference between that and the number of the ge propofed, it fhews the Odds that there - is, that a Perfon of that Age does not die in a Year. As for Inftance, a Perfon of 25 Years of Agehas the Qdds of 560 to 7, or 80 to I; that he does not die in a Year: Becaufe that of 567, living of 25 Years of Age, there do die no more than 7 ina Year, leaving 560 of 26 Years old. | | ve. *
So
— Mifcellanes Curiofa, 287 - So likewife for the Odds, that any Perfon does not die before he attain any propofed Age : Take the xvmber of the remaining Perfons of the Age propo‘ed, and divide it by the difference between it and the number of rhofe of the Age - of the Party propoied ; and that fhews the Odds there is between the Chances of the Party’s li- ving or dying. As for Inftance ; What is the Odds that a Man of 40 lives 7 Years: Take the number of Perfons of 47 Years, which in the Table is 377, and fubtract it from the number of Perfons of 40 Years, which is 4455 and the difference is 68: Which fhews that the Pexfons dying in that 7 Years, are 68, and that it is 277 to 68, or §z to f, that a Man of 40 does live 7 Years. And the like for any other anmber of Years. Ufe Ill. But if it be enquired at what num- ber of Years, it is an even Lay that a Perfon of any Age fhall die, this ‘Table readily per- forms it: For if the number of Perfons /iving of the Age propofed, be balfed, it will be found by the Table at what Year the faid Number is reduced to half by Mortality ; and that is the Age, to which it is an even Wae ger, that a Perfon of the Age propofed fhall arrive before he die. As for Inftance; A Per- fon of 30 Years of Age is propofed, the num- ber of that Age is $31, the half thereof is 265, which number J find to be between 57 and §9 Years; fo that a Man of 30 may rea- fonably expect to live between 27,.and 28 Years. ; |
. Ufe lV, By what has been faid, the Price of Infurance upon Lives ought to be regulated, and the difference ;is.-difCovered between the © ie leap PE: | Price
TEE os Se ae ao i,
288 Mifcellanea Curiofa. ~ Price of infaring the Life of a Man of 20 and So. For Example ; It being 100 to 1, thata Man of 20 dies not in a Year, and but 38 ‘to 1, for a_ Man of $0 ‘Yeats bf Age." 870" aa Ufe V. On this depends the Valuation of Annuities upon Lives ; for it is plain, that the Purchafer ought to pay for only fuch a part of the Value of the Annuity, as he has Chances that he is living ; and this ought to be com: puted yearly, and the Sum of all thofe yearly Values being added together, will amount to the Value of the Annuity for the Life of the Perfon propoféd. Now the prefent Value. of Money payable after a Term of Years, at any given Rate of Intereit, either may be had from ‘Tables already computed ; or almoft as compendioufly, by the ‘Table of Logarithms : For the Arithmetical Complement ‘of thg Lo- garithm of Unity, and its yearly” Intereft, (that is, of I, 06 for Six per Cent. being 9, 974.694.) being multiplied by ‘the number of Years pro- pofed, gives the prefent Value of One Pound payable after the end of fo many Years. Then by the foregoing Propofition , it will be as the number ‘of Perfons living after that. Term of Years, to the number dead; fo are the Odds that any. one Perfon 1s alive or dead. . And by confequence, as” the Sum ‘of both, or the number of ‘Perfons: living of the ‘Ave fart propofed, to’ the’ ‘number remaining after. fo many Years, (both given by the ‘Ta- ble) fo the~ prefent Value of the yearly Sum ayable after the Term propofed, to the Sum which ought to be paid for’ the ‘Chance. the Perfo has to enjoy fuch an’ Annuity after fo many “Years. ~ And this being repeated’ for é every
Mifcellanea Curiofa. . 289. every Year of the Perfon’s Lilie, the Sum of all the prefent Values of thofe Chances is the true Value of the Annuity. This will wich- out doubt appear-to be a moft laborious Calcu- lation ; but it being one of the principal Ufes of this Speculation, and having found jome Compen- dia for the Work, I took the pains to compute the following Table, being the fhort Refult of a not ordinary number of Arithmetical Operations : Ir fhews the Value of Annuities for every Fifth Year of Age, to the Seventieth, as fol- lows.
Age. Years Pur. ars Por. | Age.| Years Pur.
10,28 1227-4 §0 9,21 13,40 11,72 | 55) 8,51 13,44 UE eT OBC 7,60 13422 19,57 | 65) 6,54 12,78 pi ae! Se MME ook
This fhews the great Advantage of putting» Money into the prefent Fund lately granted to _ Their Majelties, giving 14, per Cent. per Annum, _or at the Rate of 7 Years Purchafe é a Life; when young Lives, at the ufual Rate of Intereft, are worth above 13 Years Purchafe. It fhews _ likewife the Advantage of young Lives over thofe in Years; a Life of Ten Years being almoft ~ worth 13% Years Purchafé, whereas one of 36 is worth but 11. 7 _ Ufe V. Two Lives are likewife valuable by the fame Rule; for the number of Chances _. of each fingle Life, found in the Table, bes ing multiplied together, become the Chances of the Two Lives. And after any certain iiss ee aL Term
290 Mifcellanea Curiofa. Term of Years, the Produ& of the two re- “maining Sums is the Cinances thar both the Perfons are living. The Product of the two Differences, being the numbers of the Dead of both Ages, are the Chances that both the Perfons are dead. And the two Produéts of the remaining Sums of the one Age multipli- ed by thofe dead of the other, fhew the Chan- ces that there are, that each Party furvives the other: Whence is derived the Rule to eftimate the Value of the Remainder of one Life after another. Now as the Produét of the Two Numbers in the Table for the T'wo Ages propofed, is to the difference between that Produét, and the Produ& of the two num- bers of Perfons deceafed in any {pace of time; fo is the Value of a Sum of Money to be paid after fo much time, to the Value thereof uns der the Contingency of Mortality. And _ as the aforefaid Product of the two Numbers an- fwering to the Ages propofed, to the Pro- duct of the Deceafed of one Age multiplied by thofe remaining alive of the other 3 fo the Value of a Sum of Money to be paid af- ter any time propofed, to the Value of the Chan-: ces, that the one Party has that he furvives the other, whofe number of Deceafed you made ufe of, in the fecond Term of the Pro- portion. This perhaps may be ‘better under- ftood, by putting N for the number of the’ younger Age, and » for that of the Elder ; T, y the Deceafed of both Ages refpectively, and R, r for the Remainders; and R -- YT == N, andr -- y= x, Then fhall Nx be the whole Number of Chances; Nm — 7, be the Chances that one of the two’ Perfons ‘is living,
DR i. aaeeeyeen Cae tag 4 aes
Mifcellanea Curtofa. 291 living, Y y the Chances that they are both dead; Ry the Chances that the elder Perfon is dead, and the younger living ; and r Y the Chances, that the elder is living, and the younger dead. Thus two Perfons of.18 and 35 are propofed, and after 8 Years thef Chances are required. The Numbers for 18 and 35, are 610 and 490; and there are s0 of the Firfk Age dead in 8 Years, and 73 of the Elder Age. There are in all 610 x 490, or 298900 Chances ; of thefé there are 50 X 73, oO: 3650, that they are both dead. And as 298900, to 298900 — 3650, or 295250: So is the prefent Value of a Sum of Money to be paid after 8 Years, to the prefent Value of a-Sum to be paid, if either of the two live. And as 560 x 73, {0 are the Chances that the ‘Elder is dead, leaving the Younger; and as 417 X $95 fo are the Chances that the Younger is dead, ‘leaving the Elder. Wherefore as G10 x 490 to $60 x 73, fo is the prefent Value of a Sum to be paid at 8 Years end, to the Sum to be paid for the Chance of the Youn- gers Survivance; and as 610 x 490 to 417% _§ fo is the fame prefent Value to the Sum to be paid for the Chance of the Elder’s Survi- _vance. . This poflibly may be yet better explained, _by expounding thefé Products by Reétangular Parallelograms, as in Fig, 7. wherein 4B or €D reprefents the number of. Perfons of the ;younger Age, and DE, B.A thofe. remain« ing aliveafteracertain Term of Years; whence ~C E will anfwer the number of thefe. dead in . that _ time +, DO AC, BD may reprefent the snumber of the elder Age; 4 F, BI the Survi- eT U2 vors
292 Mifcellanea Curiofa. —
vers after the fame Term; and CF, DI, thofe of that Age that are dead at thar time. ‘Then fhall the whole Parallelogram 4 BC D be Nz, or the Product of the two Numbers of Perfons, reprefenting fuch a number of Per-
A Ad eel
fons of the two Ages given; and by what
was faid before, after the Term propofed, the Rectangle HD fhall be as the number of Per- fons of the younger Age that furvive, and the Rectangle 4 E as the number of thofe that die. So likewife the Rectangles AI, FD fhall be as the Numbers, living and dead, of ‘the other Age. Hence the Rectangle HI fhall be as an equal number of both Ages fur- viving. The Rectangle F E being the Pro- dué& of the Deceafed, or Yy, an equal num- ber of both dead. The Rectangle GD or R}, a number living of the younger Age, and dead
of the elder: And the Reétangle 4G or r¥ a number living of the elder Age, but dead of the younger. This being underftood, it is obvious, that as the whole Retangle 4 D or
N nis to the Gnomon FABDEG or Nn—T), {o is the whole number of Perfons or Chances, to the number of Chances that one of the two Perfons is living: And as 4D or Nm is to FE or Yy, fo are all the Chances, to the “Chances that both are dead; whereby may be computed the Value of the Reverfion after both Lives.) And as AD to GD of Ry,
“{o the whole number of Chances, to the Chan-
ces that the younger is living; and the other dead ; whereby may be caft up what Value ought to be paid for the Reverfion of one Life ‘after another, as in the Cafe of providing for ~ Clergy-men's Widows, and others, by fuch
Reverfions. |
bof) ot) Bu Mas 2a eel ialat si Seki sci Mifcellanea Curtofa. 293 Reverfions. Andas 4D to AG, orrY, fo are all the Chances, to thofe that the elder furvives the younger. I have been the more particular, and perhaps tedious, in this Matter, becaule it is the Key to the Cafe of Three Lives, which of it felf would not bave been fo eafie to com- rehend. VII. If Three Lives are propofed, to fnd the Value of an Ansuity during the continu- ance of any of thofe three Lives; the Rule is, As the Produé& of the continual Multiplica- tion of the Three Numbers, in the Table, anfwer- ing to the Ages propofed, is to the difference of that Produ&, and of the Produtt of the Three Numbers of the Deceafed of thofe Ages, im any given Term of Years: So is the prefent Value of a Sum of Money, to be paid certainly after fo many Years, to the prefent Value of the famz Sum to le paid, provided one of thofe Three Perfons be living at the Expiration of that Term. Which Pro- _ portion being yearly repeated, the Sum of all —thofé prefent Values wi!l be the Value of an Annuity granted for three fuch Lives. But to’ explain this, together with all the Cafes of - Survivance in Three Lives: Let N be the Number in the Table for the younger Age, n for the fecond, and v for the e'der Age ; let Y be thofe dead of the younger Age ia the Term propoied, » thofe dead of the fecond _ Age, and vu thofe of the elder Age ; and ler R be the Remainder of the younger Age, y that of the middle Age, and ¢ the Remainder of the elder Age. Then fhall R +-Y be equal to N, r ~- y to n, and eg -v tov, and the con- tinual Product of the three Numbers N, 2, 1%, fhall be equal to the contiiual Product of aoe U3 R
Pes ae dew SE GUM RIE eA eet) eee , PAREN ee ee Pay : ees ES 3 }
294 Mifcellanea Curiofa,
R+Yx r+ yx ¢-- v, which being the whole Number of Chances for three Lives, is com- pounded of the cight. Produéts following. (1) R re, which is: the Number of Chances that all three of the Perfons are living. (2) re 2% which is the Number of Chances that the two elder Perfons are living, and the younger dead. (3) Rey the Number of Chan- ces that the middle Age is dead, and the youn- ger and elder living, (4) R 7 wv being the ~ Chances that the two younger are living, and the elder dead. (5) ¢ Yy the Chances that thetwo younger are dead, and the elder li. ving. (6)r Yu the Chances that the younger and elder are dead, and the middle Age Ii ving. (7) Ry which are the Chances that
'. the younger is living, and the two other
dead. And Laftly and Eighthly, Yyv, which are the Chances that all three are dead. Which latter fubtracted from the whole Number of Chances Nav, leaves Nnv—Yyv the Sum of all the other feven Products; in all of which one or more of ithe three Perfons are. furviving. :
To make this yet more evident, I have ad- ded Fig. 8. wherein thefe eight feveral Pro- du&s are at one view. exhibited. Let the — reCtangled Parallelepipedon «BCDEFGH be conftituted of the fides 4B, GH, €5c. proportional to N the Number of the youn- ger Age ; AC, BD, &c. proportional to n; and 4G, C E, €c. proportional to the Num-
_ ber of the elder, or % And the whole Paral- lelepipedon fhall be as the Product Nx », or our whole Number of Chances. Let BP be asR, and 4 P as Y; let C L beas r, ‘and Ln | co aS
Mifcellanea Curiofa. 295 ~asy3 and GN ase, and NA asv; and let the Plain P Rea be made parallel to the Plaia ACGE; the Plain NVDY parallel tao ABCD; and the Plain LXTQ parallel to the Plain ABGH.. And our firlt Produ& Rr ¢ fhall be asthe Solid §$ TIF Zeb. The Second, or r »T will be as the Solid EY Ze QS MI. ~The Third, R ey, asthe Solid RHOVH7IST. And the Fourth, Rrv, asthe Sold Zab DWXIK, _|Fifthly,' ¢ Yy,; as the Solid GOQRSIMNO. ‘Sixthly, , Yu, as IK LMGYZ 4.. Seventhly, Rv, as the Solid IK POBXVW.,. And Laftly,'41KiLMNOP will be as the Pro- duét- of the 3 Numbers of Perfons dead, or Ty v. I fhall not apply this in all the Cafes _ thereof, for brevity-fake ; only to fhew in one how all the reft may be performed, let it be demanded what is the Value of the Reverfion of the younger Life after the two elder pro- pofed, The proportion is as the whole Num- ber of Chances, or Nn.v to the Produ& Ry »; fo is the certain prefent Value of the Sum payable after any Term propofed, to the Value due to ‘fuch Chances as the younger Perfon has to bu- ry both the elder, by the Term propofed ; which therefore he is to pay for. Here it is to be noted, that the firft Term of all thefe Proportions is the fame throughout, wiz. Nn». The fecond changing yearly according to the _Decreafe of R, r, ¢, and Increafe of Y, », v. _ And the third are fucceflivelo the prefent Va- lues of Money payable after ‘one, two, thrée, ec. years, according to the Rate of Intercft agreed on. ‘Thefe Numbers, which are in ail Cafes of Annuities of neceflary Ufe, Ihave put into the following Table, they’ betng’ Decimal Be oy U 4 Values,
ees, 2 SIN PO DS Ware ec, © ye ee
296 «= Mifcellanea Curiofa. Values of one Pound payable after the Num-
ber of Years in the Margent, at the Rate o 6 per Cent. ote G2
Caen eee en ae Yearse |Preit. Va-|Years. |Prel. Vas| Years. |Pref.Va-
lue of 11. TE 1999434 2 |0,3990 | 3 [2.8396 ee cay des 5 97473 6 |o,7050 7 10,6650 8 |0,6274 9 jaxs9I9 19 0,5 534 Il |0,5268 I2 j0,4.970 | - 12 10,4688 14. [0244-23 15 [0.4173 16 0,3936 17 193714
18 |0,32503
It were needlefs to advertife, that the great. trouble of working fo many Proportions will be very much alleviated by ufing Logarithms ; and that inftead of ufing Nnv—Yy v for the fecond Term of the Proportion in finding the Value of Three Lives, it may fuffice to ufe only Y y v, and then deducting the fourth Term fo found out of the third, the Remain-
der fhall be the prefeat Value fought; or all ial et, Nea ticam bate lai
Mifcellanea Curiofa. 297 thefe fourth Terms being added together, and deduéted out of the Value of the certain Annui- ty for fo may Years, will leave the Value of the contingent Annuity upon the Chance of Mor- tality of all thofé Three Lives. For Example ; Let there be Three Lives of 10, 20, and 40 Years of Age propofed, and the Proportions will be thus ; | hae
As 661in $31 in 44.5 or 156190995, or Nnv _ to 8in 8 in 9, or 576, or Vy for the firft ; Year, fo 0,94.34. to 0,00000348. To 15 in 16 in 18, or 4320, for the fecond Year, fo 0,8900. to 0,00002462. To 21-in 24 in 28, or 14112 for the third , ~ Year, fo 0,8396. to 0,00008128. ‘Fo 27 in 32 in 38, for the fourth Year, fo : O,;7921. to 0,00016650. To 33 in 41 in 48, for the fifth Year, fo | 0574.7 3. t0 0,00031071. To 39 in 50 in 58, for the fixth Year, fo 0,705Q. to O,00051 051.
And fo forth to the 6oth Year, when we fuppofe the elder Life of Forty certainly to be expired; from whence till Seventy we muft compute for the Firft and Second only, and from thence to Ninety for the fingle _youngeft Life. Then the Sum Total of all thefe Fourth Proportionals being taken out of ‘the Value of a certain Annuity for 90 Years, being 16,58-Years Purchafe, fhall leave the ju Value to be paid for an Annuity during _ the whole Term of the Lives of Three Per-
fons of the Ages propofed. And note, that it
eee a eee ee will
UR uy Hh SiR A Rect Rae i fg NN Aaah COM SB
298 Mifceilariea Curiofa, will not be neceflary to compute for every Year fingly ; but thac in moft Cafes every 4th or sth Year may fuffice, interpoling-fer the intermedi- ate Years feeundum artem. 9 9
It may be objected, that the different Salu- brity’ of Places does hinder this Propofal from being univerfal 5 nor canit be denied. But by the Number that die, being 1174. per Annum in 34.000, it does appear that about a 3oth part die yearly, as Sir Wslliam Petty has com-— puted for London ; and the Number that die in Infancy, is a good Argument that the Air is but indifferently falubrious. So that by what I can learn, there cannot perhaps be one better Place propofed for a Standard. At leéaft ‘tis defired, that in Imitation hereof the. Curious’ in other Cities would attempt fomething of the fame Na- ture, ‘than which nothing perhaps can be more ufeful. _ . te veot |
Were this Calculus founded on the Experience of a very great number of Years, it would be ve- ry well worth the while to think of Methods for facilitating the Computation of the Value of two, three, Or more Lives ; which, as propofed in my former, feems (as I am inform’d) a Work — of too much Difficulty for the ordinary Arithme- tician to undertake. Mg EEN +
I have fought, If it were poffible, to find a ‘Theorem that might be more concife than the Rules there laid down, but in vain; for all that can be done to expedite-it, is, by ‘Ta- bles of Logarithms ready computed, to exhibr the Rationes of N to Y in each fingle Life, — for every third, fourth, or fifth Year of Age, -as occafion fhall require; and thefe, Loga-. rithms being added to the* Logarithms of the
| : prefent —
Mifcellanea Curiofa. 299 prefent Value of Money payable after fo many ears, will give a Series of Numbers, the Sum of which will fhew the Value of the Annuity fought. However, for each Number of this Series, two Logarithms for a fingle Life, three for two Lives, and four for three Lives, muft neceffarily be added together. If you think the Matter, under the Uncertainties I have men- tioned, to deferve it, I fhall fhortly give you fuch a Table of Logarithms, as I {peak of, and an Example or two of the ufe thereof: But by Vulgar Arithmetick, the Labour of thefe Num- ‘bers were immenfe ; and nothing will more re- commend the ufeful Invention of Logarithms © to all Lovers of Numbers, than the advantage of Difpatch in this and fuch like Computa- tions.
Befides the Ufes mentioned, it may perhaps not be an unacceptable thing to infer from the fame Tables, how unjultly we repine at the fhortnefs of our Lives, and think our felves wronged if we attain not old Age; whereas it appears hereby, that the one half of thofe that are born are dead in Seventeen Years time, 1238 being in that time reduced to 616, So that inftead of murmuring at what we call an untimely Death, we ought with Patience and Unconcern to fubmit to that Diffolution which is the neceflary Condition of our perifhable ‘Materials, and of our nice and frail Stru€ture and Compofition: And to account it as a Blefling that we have furvived, perhaps by ma- ny Years, that Period of Life, whereat the one half of the whole Race of Mankind does not arrives ae
. .
A
RR ah og Pt) Aim iia tN. 2 aR it Lai"
300 - Mifcellanea Curiofa. : _ A fecond Obfervation I make upon. the faid r Table, is that the Growth and Increafe of Man- kind is not fo. much ftinted by any thing in the - Nature of the Species, as it is from the cautious — difficulty moit People make to adventure on the State of Marriage, from the Profpe& of the” ‘Trouble and Charge of providing for a Family. © Nor are the poorer fort of People herein to be blamed, fince their difficulty of fubfifting is eccafion’d by the unequal Diftribution of Pof- fetfions, all being neceflarily fed from the Earth, of which yet fo few are Mafters. So that be- fides themfelves and Families, they are yet to work for thofe who own the Ground that feeds them: And of fuch does by very much the greater part of Mankind confit; otherwife it is plain, that there might well be four times as many Births as we now find. For by Compu- tation from the Table, I find that there are near- ly 15000 Perfons above 16, and under 45, of which at leaft 7000 are Women capable to bear Children. Of thefe notwithftanding there are but 1238 born yearly, which is but little more than a fixth part: So that about one in fix of thefe Women do breed yearly; whereas were they all married, it would not appear ftrange or unlikely, that four of fix fhould bring a Child every Year. The Political Confequences here- of I fhall not infift on; only the Strength and Glory of a King being in the multitude of his Subjeéts, I fhall only hint, that above all things, Celibacy ought to be difcouraged, as, by ex- traordinary Taxing and Military Service: And thofe who have numerous Families of Children to be countenanced and eacouraged by fuch Laws as the Fus trium Liberorum among the Ro- mans,
7
Se RMT SARIN By gy! ae
- Mifcellanea Curiofa. © 301 mans. But efpecially, by an effe€tual Care to provide for the Subfaftence of the Poor, by find- ing them Employments, whereby they may earn ‘their Bread, without being chargeable to the Publick, |
ete 4 4 : s () , q . - | ae . q t
‘ wer acca seme Re ee Se ee 0 A ye se ee ST ‘ os - —=. = —
an ARS ae oe sia i
pete iaieion +!
302 Mifcellanea Curiofa. . |
A Difcourfe concerning Gravity, and its Properties, wherein the De- _ {cent of Heavy Bodies, and the ‘Motion of Projects is briefly, but fully handled: Together with the Solution of aProblem of great UfeinGunnery. ByE. Halley.
N ATURE, amidft the great Variety of Problems , wherewith She exercifes the Wits of Philofophical Men, fcarce affords any one wherein the Effect is more vifible, and the Caufe more concealed, than in thofe of the Phenomena of Gravity. Before we can go a= lone, we muft learn to defend our felves from the Violence of its Impulfe, by not trufting the Center of Gravity of our Bodies beyond our reach ; and yet the acuteft Philofophers, and the fubti- left Enquirers into the Original of this Moti- on, have been fo far from fatisfying their Rea- ders, that they themfelves feem little to have — underftood the Confequences of their own Hypo- thefes. : ' Des Cartes his Notion, I muft -needs confefs to be to me incomprehenfible, while he will have the Particles of his Celeftial Matter, by being refle&ted on the Surface of the Earth, and fo afcending therefrom, to drive down in-
to their Places thofe Terreftrial Bodies they find | above
Mifcellanea Curiofa. 302
above them: This is, as near as I can gather, the Scope of the 20, 21, 22, and 22 Seé&ions of the laft Book of his Principia Philofophic ; yet neither he, nor any of his Followers, can fhew how a Body fufpended in Libero Athere, fhall be carried downwards by a continual Im- pulfe tending upwards, and aGting upon all its Parts equally : And befides the Obfcurity where- with he exprefles himfelf, particularly, Seé. 22. does fufficiently argue according to his own Rules, the confufed Idea he had of the thing he wrote. .
Others, and among them Dr. Voffius, aflert the Caufe of the Defcent of heavy Bodies, to be the Diurnal Rotation of the Earth upon its Axis, without confidering , that according to. the Doétrine cf Motion fortified with Demonttra- tion, all Bodies moved in Circulo, would recede from the Center of their Motion ; whereby the contrary to Gravity would follow, and all loofe ‘Bodies would be caft into the Air in a Tangent to the Parallel of Latitude, without the interven- tion of fome other Principle to keep them faft, fuch as is that of Gravity. Befides, the Effect of this Principle is throughout the whole Surface of the Globe found nearly equal ; and certain Experiments have proved it rather lef near the Aquinoétial, than towards the Poles; which could not be by any means, if the Diurnal Rotation of the Earth upon its Axis were the Caufe of Gravity; for where the Motion was — the ‘Effe& would be moft confider- able. : Others affign the Preffure of the Armo/pheres to be the Caufe of this Tendency towards the Center of the Earth ; but unhappily they have
| miftaken
204 Mifcellanea Curiofa, miftaken the Caufe for the Effect; it being — from undoubted Principles plain, that the Ar- — mofphere has no other Preffure but what it de- rives from its Gravity; and that the. Weight of 4 the upper Parts of the dir, prefling on the low- er Parts thereof, do fo far bend the Springs of © that Elaftick Body, as to give it a Force equal — to the Weight that comprefs’d it, having of it” elf no force at all: And fuppofing it ‘had, ic will be very hard to explain the Modus, all that Preffure fhould occafion the Defcent of a Body circumfcribed by it, and prefled equally — above and below, without fome other Force to draw, or thruft it downwards. But to demon-_ {trate the contrary of this Opinion,.an Experie ment was long fince fhewn before the Royal So- | ciety, whereby it appeared, that the Armofphere was fo far from being the Caufe of Gravity, that the Effects thereof were much more vigorous, where the Preffure of the Atmofphore was taken” of ; for a long Glafs-Receiver having a light Down-feather included, being evacuated of Air, the Feather, which in the Air would hardly fink, did in vacuo defcend with nearly the fame Velocity, as if ic had been a Stone. a
Some think to illuftrate this Defcent of Hea- ‘vy Bodies, by comparing it with the Vertue of the Loadftone; but fetting afide the diffe- rence there is in the manner of their Attraéti- ons, the Loadftone drawing only in and abou 7 its Poles, and the Earth near equally in all Parts of its Surface, this Comparifon avails no more than to explain ignotum per aque ignotum. — ' | | ;
Others
Mifcellanea Curiofa. 3.05
Others aflign a certain Sympethetiaal Attratti- on between the Earth and its Parts, whereby they have, as it were, a defire to. be united, to be the Caute we enquire after: ‘But’ this is fo far from explaining the Modus, that it is’ lit- tle more, than to tell us in other Terms, that Heavy Bedies defcend, becaufe they de- feends 90) 3 to sts Sui to Howat This, I fay, not that I can pretend to fub- ftirute any Solution of this Important Philofophi- cal Problem, that fhall more happily: explicate the Appearances of Gravity ; only. ic may be fer- sviceable to thofe with whom the Credit of great Authors fways much, and who too readily-affent in Verba Magiftri, to let them fee that their Books sare not always infallible’: Befides, rhe deteCtion of Errors isthe firftvand fureft: Step tewards the difeovery of Truth. - lonwy iant Jo Though the efficient Caufe of Gravity be.fo abfcure, yet the final Caufe thereof is clear e- ‘nough ; for ic is by this fingle Princip/e, that the ‘Earth and all the: Celeftial Bodies are kept. from Diffolution ; the leaft of their: Particles not being fuffer’d rovrecede far from their Surfaces, with- out being’ immediately brought down again by Virtue of this Natural Tendency 3 which, for their Prefervation, the Infinite Wifdom of ‘their, Crea- tor»-has ordained to. be towards each’ of. their Centers‘ norocan the Globes of the Sun and Planets otherwife ‘be edeftroy’d, but by; taking from them ‘this’ Power of keeping their Parts ‘united. — ahi on, ' Litt beta iGo oasel : . The Affeftions or Properties of Gravity, and its. manner of aGing upon Bodies falling, have been in a great meafure difcovered, and mot of them made out by) Mathematical. Demonftra- PSIMIOI?S x tion
median hs i M9) i Pose em SN iat
00 Mifeellanes Curiofe.
‘ion inthis. our Century, by the accurate. dili- gence) of Galileus, Torricellius, Hugeniusy and O-- thers, and now lately by our worthy Country- anans, Mriil/aac Newton, which Properties it. may be very material here to enumerate, that’ they may» ferve for a Foundation io all thofe that fhall be willing to fpend, theie Thoughts in — fearch of the true Caufe of this Defcent of Bo- . en 08), hu3i97 yon a | PI
ois'The frft. Property is, That by. this'. Princi- ple of Gravitation, .all Bodies do defcend to-— wards a Point, which either is, or elfe is vye= ty) meat to. the Center of Magnitude of the ~~ Earth sand Sea, about which the Sea forms. it felf exactly. into, a S$ pherical Surfaces and; the Prominences of the, Land,:confidermg the Bulk ef the whole, differ but infenfibly there Gromas aicaxd,, 10. Sted 24} RRC De col
°1'1 Secondlyy. That this Point or Center of Gravi- ation, as fix’d within the Earth, vor at lealt has been fO,ever fince::we have any, duthentick Hi-
fiory: For a Confequence of its‘Change, though © riever fo little, would:be the over-flowing of:the ow Lands on that fide of the Globe otowards — which it approached, and the leaving new Ilands_ bare on the oppofite fide, from which it -reced- ed®; ‘but for this ‘Two Thoufand: Years. it ap-_ pears, that the low. Iflands -of the Medi terrancan Sca‘( near to which the-ancienteft' Writers livid) have continued much at the fame height above — the Water, as theymow are found; and no In- i sindations or Receffes of the. Sea arguing any fuch 4 Ghange,°are recorded in Hiftory:; excepting the © Dulorvfal Deluge, which can mo Detter way be UR x accounted —
Mifcellanea Curiofa. 207 accounted for, than by fuppofing this Center of Gravitation removed for a time, towards the middle of the then inhabited Parts of the World ; and a change of its Place, bur the Two Thott . fandth Part of ‘the Radius of this Gisbe, were luf- ficient to bury the Tops of the hoe Hills un- cer Water.
Thirdly, ‘That in all Parts of the Surface of the Earth, or rather in all Points equidiftant from its Center, the Force of Gravity is nearly equal ; fo that the length of the Pendulum vi- brating Seconds of Time, is found in all Parts of the World to be very near the fame. Tis true at St. Helena, in the Latitude of 16 Degrees South, 1 found that the Pendulum of my Clock, which vibrated Scconds', needed to be made fhorter than it had been in England, by a very fenfible Space (but which at that time I neg- leéted to obferve accurately) before it would keep time ; and fince the like Obfervations have been’ made by the French Obfervers, ‘near the A:quinottial : - Yer I dare not affirm, that in mine it proceeded from any other Caufe, than the great Height of ‘my Place of Obfervation above the Surface of the Sea, whereby the Gravity being: diminifhed, the length of the _ Pendulum vibrating Seconds,” is bic Hert ned. ”
\ Fourthly, Tht ¢ & cin) does da uay’ affed all seus, without regard either’ ‘to their Marter, Bulk, or Figure; {o that the Impediment of
“Medium being removed, the moft ‘com- act and moft loofe, the* greqreft and {malieft Bodies’ would defcend’ the fame Spaces in equal aa teWOs X 2 Times ;
308 = Mifcellanea Curiofa.
Times; the Truth thereof will: appear from the Experiment I before-cited. In thefe rwo lait Particulars, is {hewn the great difference be- ‘tween Gravity and Magnetifm, the one affecting only Iron, and that towards its Poles, the other
all Bodies alike in every part. Asa Corollary,
from hence it will follow, that there is no {uch ‘thing as pofitive Levity, thofe things that appear light, being only comparatively fo ; and where- as feveral things rifeand {wim in Fluids, ’tis be- _caufe, Bulk for Bulk, they are not fo heavy as thofe Fluids; nor is there any Reafon why Cork, for Inftance, fhould be faid to be light, becaufe it {wims on Water, any more than Irom, becaufe it fwims on Mercury.
Fifthly, That this Power incieafes as you de- {cend, and decreafes as you afcend from the Cen- ter, and that in the Proportion of the Squares of the Diftances therefrom reciprocally, fo as at a double Diftance to have but a quarter of the. Force ; this Property is the Principle on which Mr. Newton has made out all the Phenomena of the Cwleftial Motions, fo eafily and naturally, that its Truth is. paft Difpute. Befides . that, it is highly rational, that the attraétive or gra vitating Power thould exert it felf more. vigo- roufly ia a fmall:Sphere, and weaker in a grea- ter, in proportion as it is contracted or ex- panded ; and if fo, feeing that the Surfaces of Spheres: are as the Squares of thew Radii, this Power, at feveral Diftances,. will be, as the Squares of thofe Diftances reciprocally 3 and then its whole Action upon cach Spherical. Surface, be it great or final, will, be always. equal And this. is evidently. the Rule of Gravicarion pe ae A
| Mifcellanea Curiofa. 309 towards the Centers of the Sur, Fupiter, Saturn and the Earth, and thence is reafonably ix- ferred, to be-the general Principle obferved by Nature, in all the reft of the Cwleftial Bodies. ; :
Thefe are the principal AffeCtions of Gravity, from which the Rules of the Fall of Bedics, and the Motion of Projets are Mathematicaily dedu- cible. Mr. Ifzac Newten has fhew’d how to de- fine the Spaces of the D-/cent of a Body, let fall from any given height, down to the Center, fuppofing the Gravitation to increale, as in the fifth Property ; but confidering the fmallnets of heighth, to which any Proje can be made -afcend, and over how little an Arch of the Globe it can be caft by any of our Engines, we may well enough fuppofe the Gravity equal through- out, and the Defcents of Projeés in parallel Lines, which in Truth are towards the Center, the dif- ference being fo {mall as by no means to be dif- covered in Pra&ice. ‘The Oppofition of the Air, ’tis true, is confiderable againft all light Bodies moving through it, as likewile againft {mall ones (of which more hereafter) but in great and ponderous Shot, this Impediment is found’ by Experience but very {mall, and may fafely be neg- lected.
Propofitions concerning the Defcent of Heavy Bodies. and the Motion of Projeéts.
- Prop. I. The Velocities of Falling Bodies, are
proportionate to the Times from the beginning of their Falls. ms
<5 This
310 = Mifcellanea Curiofa. | This follows, for that the AGtion of Gravity — being continual, in every Space of Time, the fal- © ling Body receives 2 new Impulfe, equal to what it had before, in the fame Space of "Time, recei- ved from the fame Power: For Inftance, in the firft Second of Time, the falling Body has ac- quired a Velocity, which in that time would car- ry it toa certain Diftance, fuppofe 32 Foot, — and were there no new Force, would defcend at — that rate with an equable Motion. But in the next — Second of Time, the fame Power of Gravity con- tinually acting thereon, fuperadds a new Velocity — equal to the former ; fo that at the end of two — Seconds, the Velocity is double to what it was at — the end of the firft, and after the fame manner — may it be proved to be triple, -ar the end of the — third Second, and fo on.. Wherefore the Veleci- ties of falling Bodies, are proportionate to the Time of their Falls, Q..E.D. |
Prop. II. The Spaces defcribed by the Fall of a Body, are as the Squares of the “Times, from . the beginning of the Fal. : 7
Demonftration. Let A B (Fig.g. Tab. 4.) re-_ prefent the Time of the Fad! of a Body, BC per- | pendicular to AB, the Velocity acquired at the end of the Fal/, and draw the Line AC3 then divide the Line A B reprefenting the Time, ir- to as many equal Parts as you pleafe, as b, b, b, b, €%c. and through thefe Points draw the Lines bc, bc, be, bc, $c. parallel to BC, ’tis ma- nifeft that the Several. Lines, be, reprefent the feveral Velocities of the falling Body, in fuch Parts of the Time as Ab is of AB, by the for- mer Propofition. It is evident likewife, that the ee a ay ie
Plate 4. pag jto Be?
Bo
zal L
Ss 8 Sy
Ss Sy
» i)
PS
COTTE TT TT are ——————
rN _ LJ
COCCI TT een
8 _ uae 7 gS REY
QQ i=)
aS} iy
hs th 8
‘)
Pate] 8 =) ol -
ie iS
nk eRe eS Rae
Mifcellanea Curisfa. 31%
‘Area’ ABC is: the Sum*of alt the «Lines be’be- dog taken, according to ithe Method of Indi%?- fbles, infinitely many ; fo’ that the drea ABC reprefents the Sum® of all the Velocities, between _ none and BC fuppofed infinitely many ; which ‘Sum is as the Space defcended in the Time re- prefented by AB: And bythe fame Reafon the - Areas Adc, will reprefent the Spaces defcended
in the’ Times Ab; fo then the Spaces defcend ed: in the Times AB, Ab; areas the Areas of the Triangles“ ABC, Abc, which by the 20th of the 6 of Euclid, are as the Squares of their “Homologous Sides AB, A’b, that is'to fay, of the Times: Wherefore the Defcents of falling Bodies, are asthe Syuares of the Times of their Fall, emems 21a eli 30’: | :
Prop. III: The Velocity which’ a falling Rody acquires in any Space of time , is double to that, wherewith it would have moved the Space, de- fcended: by an equable Motion, in the fame time. —
Domonftration. Draw the Line EC parallel to AB, and AE parallel to BC in the fame Fig. 9. and compleat the Parallelogram ABCE, it is evident that the Area thereof may reprefent the Space, a Bedy moved equably wich the 1- locity BC would defcribe in the Time A B, and the Triangle ABC reprefents the Space defcriv’d by ‘the Fall of a Body, in’ the fame Time A P, by the fecond Propolition, Now ‘the Triangle ABC is half of the Parallelogram ABCE ; ‘and confequently the Space deferibed by the
Fall, is half what would have been defribed by an equable Motion with the Velocity’ BC, in the GEL oA fame
312 Mifcellanea Curiofa. fame-'Time ; wherefore the Velocity BC at. the end of the Fall, is double to-that Velocity, which in the Time A B, would have deferibed the Space. fallen, veprefented by the Triangle ABC with an — equable Motion, QE. D.. Oyite i rae ie -.|; Prop. TV.-All Bodies on or near the’ Surface of the Earth, in their Fal/,,.defcend, fo, as at the end of the firft Second cf. Time, they have de- {cribed 16 Feet, 1 Inch, London Meafure, and acquired the Velocity of 32 Feet, 2 Inches, in a Second. , ote a ade This, is made out from. the 25th Propofition of the fecond Part. of that excellent Treatife of Mr. Hugenius de Horologio Ofcillatorio; wherein he demonftrates the time of the leaft Vibrations of a Pendulum, to be tothe Time of the Fall of a Body, from the heigth of half the length: of the Peudulum, as the Circumference of a Circle. to. its Diameter 5 whence, as a Corollary tt follows, That as the Square of the Diameter to the Square.of the Circumference, fo half the length of the Pendulum vibrating Seconds, to the Space defcribed by the Fall of ‘a Body in a Second of Time: And. the Length of the Pendulum vibrating Seconds, being found 39,125, or & Inches, the. Defcent in a Second will be found by the aforefaid Analogy 16 Foot and 1 Inch ; and, by the third Propofition, the Velocity will be double thereto; and near to this it hath been found by feveral Experiments, which. by ‘reafon of the fwiftnefs.of the Fall, can- — not fo exactly determine its Quantity. The De- monftration of Hugenius being the Conclufion of along Train of Confequences, 1 fhall for brevity fake omit; and refer you to his Book, where thefe things are more amply treated of. __ Oe ag ee hime sm ‘} babs: z From
Mifcellanea Curiofa. 313 From thefe Four Propofitsons, all Que/tions con- cerning the Perpendicular Fall of Bodies, are eafi- dy folved, and either Time, Height, or Velocity being aflign’d, one may readily find the other two. From them likewife is the Doétrine of Projefts deducible, affuming the two following Axioms ; viz. That a Body fet. a moving, will move on continually ina right Line with an equa- ble Motion, unlefs fome other Force or Impedi- ment intervene, whereby it is accelerated, or re- -tarded, or defle&ted. oan Secondly, ‘That a Body being agitated by two Motions at a time, does by their compounded Farces pafs through the fame Points, as it would da, were the two Motions divided and acted fucceffive- ly, As for Inftance, Suppofe a Body moved in the Line GF, (Fig. 1. Tab. 5.) from G toR, and there ftopping, by another Impulfe, fuppofe it moved in a Space of Time equal to the former, from R towards K, to V. I fay, the Body fhall pais through the Point to V, though thefe two Several Forces a€ted both in the fame rime.
oe Prop. V. The Motion of all Projects is in the Curve of .a Parabola: Let the Line GRF (in Fig. 1.) be thé Line in which the Proje is di- rected, and in which by the firft Axiom it would move equal Spaces in equal Times, were it not deflected downwards by the Force of Gravity. Let GB be the Horizontal Line, and GG a Perpendicular thereto. ‘Then the Lixe GRF being divided into equal Parts, anfwer- ing to equal Spaces of Time, let the Defcents of the Projet be laid down in Lines parallel toG C, proportioned as the Squares of the Lines GS, G R, G L, G F; or as the Squares of the ai ot ae ae rom
214 Mifceilanea Curiofa, from:S to T, from R to V, from L to X, and. from F to B, and draw the Lines TH, VD, XY, BC parallel to GF; I fay, the Points T, V, X, B, are Points’ in the Curve delcribed — by the Projeé, and that that Curve is 4 Parabola. By the fecond Axiom, ‘they are Points in the Curve ; and the Parts of the Defcent GH, ‘GD, GY, GC, = to ST, RV, L Xy'F By being as the Squares of the Times (by the’ Second Pro- pofition). that is, as the Squares of the Ordinates, HT, DU, Y X, BC, equalto GS, GR, GL, GF, the Spaces meafured in thofe Times’;: and there being no ‘other Curve but the Parabola, whofe Parts of the Diameter are as the Squares of the Ordinates, it follows that the ‘Curve ‘de- {crib’'d by a Proje&t, can be no other than a Pg- rabola: And faying, as RU the Defcent in any time, to-GR or UD the direé& Motion in the fame time, fo is UD to a third proportional s that rhird will be the Line call’d by all Writers of Conicks, the Parameter of the Parabola to the Diameter GC, which is always the fame in Prejeéts caft with the fame Velocity: And the Ve= locity being defined by the Number of Feet mo- ved in-a Second of ‘Time, the Parameter will be found by dividing the Square of the Velocity, by 16 Feet, 1 Inch, the Fall of a Body in the fame Trae. ae
Lemma.
The Sine of the double of any Arch, is equal
to twice the Sine of that Arch into its Co-fine, di-
vided by Radius; and the verfed Sine of the
double of any Areh is equal to twice the Square of
the Sine thereof divided by Radius. ap | . WCE
ee
Mifcellanea Curiofa, 315
Let the rch B C (in Fig, 2. Tab. 5.) bedouble
- the Arch BF, and A the Center 3 draw the Ra- dii AB, AF, AC, and the Chord BD C, and Jet fall BE perpendicular to AC, and the An- gle EBC, will be equal to the Angle ABD, and the Triangle BCE, will be like to the Tri- angle BD A; wherefore it will be as AB to AD, fo BC or twice BD, to BE; that is, ds ~ Radius to Co-fine, fo twice Sine to Sine of the double 4rch. And as AB to BD, fo twice BDor BC to EG, that is, as Radius to Sine, fo twice that Sine, to the Verfed Sine of the double Arch ; which two Analogies refolved into Equations, are the Propsfitions contained in the Lemma to be proved. | Se es
Prop. VI. The Horizontal Diftances of P,o- jeétions made with the fame Velocity, at feveral Elevations of the Line of Dire&tion, are as the Sines of the doubled Angles of Elevation. ?
Let GB (Fig. 1.) the Horizontal Diftance be =x, the Sine of the Angle of Elevation, PGB, be = s, its Co-fine = c, Radius = ry and the Parameter = p. It will be as c tos; fo 2 to
= F B= GC, and by reafon of the Parabola PS%— to the Square of CB, or GF; Nowasc ¢ iS |
| : r Bs ; to rs fo is to u = GF, and its Square 137° i eet
will be therefore = to?*%. Which Euation
reduced will be ae But by the former oy rr | 4
25¢, : ’ Lemma rae. equal to the Sine of the dou-
ue
316 = Mifcellanea Curiofa: ble Angle, whereof s is the Sine: Wherefore ewill be’as Radius to Sine of double the Angle F GB, {0 is half the Parameter, to the Horizon- tal Range or Diftance fought ; and at the feveral Elevations, the Ranges are as the Sines of the double Angles of Elevation, Q. E. D. |
- Corollary. -
Hence it follows, that half the Parameter isthe greateft Randon, and that that happens at the Elevation of 45 Degrees, the Sine of whofe dou- ble is Radius. Likewife that the Ranges equally diftant above and below 45 are equal, as are the Sines of all double Arches, to the Sines of their doubled Complements. | :
Prop. VII. The Altitudes of Projeétions made with the fame Velocity, at feveral Elevations, — are as the verfed Sines of the doubled Angles of
e 8 ee) § ¢ Elevation: Asc is to s3 fo is* *"—GB to.
p< *= BF: and UK=: RU= BE thai cee oud Bip ae = titude of the bhiadin 6 ae ye Now by the
258 mere oe —— a) the verfed Sine of
foregoing Lemma the double Angie, and therefore it will be as Ra-— dius, to verfed Sine of double the Angle FGB, fo an 8th of the Parameter to the height of - the Projeétion VK; and fo thefe heights at fe- veral. Elevations, are as the faid verfed Sines;
Q. BE. D. | | Coro, Mary. —
Mifcellanea Curiofa. 317 | Corollary.
From hence it is plain, that the greateft A/ri- tude of the perpendicular Projeétion is a 4th of Pa- rameter, or half the greatelt Horizontal Range ; the verfed Sine of 180 Degrees being = 27,
Prop. VII. The Lines GF, or Times of the Plight of a Proje& caft with the fame Degree of Velocity at different Elevations, are as the Sines of the Elevations.
Ase is tor; ois’2£_— GB by the 6 | tt )
Prop. to Tae A that is, aS Radius to Sine of Elevation, fo the Parameter to the Line GF; fo the Lines GF are as the Sines of Elevation, and the Times are proportional to thofe Lines ; wherefore the Times are as. the Sines of Elevation :
Ergo conftat propofitio.
Prop. 1X. Problem. A Projection being made as you pleafe, having the Diftance and Altitude, or Defcent, of an Object, through which the Project paffes, together with the Angle of Eleva- tion of the Line of Direttion 5 to find the Para meter and Velocity, that is (in Fig. 1.) having the Angle FGB, GM, and MX. -
-- Solution, As Radius to Secant of FGB, foGM the Diftance given to GL ; and as Radius to Tan- gent of FGB, fo GM to LM. Then LM — MX in Heights, or +.MX in Defcents ; or ele MX — ML, if the Dircétion be below the Horizontal Line, is the Fall in the Time that the direct Impuife given. in G would have ne hh i the
318 Mifcellanea Curiofa. | the Project from G to L=LX=GY 5 then by. Reafon of the Parabola, asL XK or GY, 1s to GLor YX, foisGL tothe Parameter fought. To find the Velocity of the Impulfe : by Prop. 2, and 4, find the Time in Seconds that a Body would fall the Space L,X3; and by that dividing the Line GL, the Quore will be the Velocity, or Space moved in a Second fought, ‘which is always. a mean Proportional between the Parameter, and 16 Feet, 1 Inch.,
Prop. X. Problem 2. Having the Parameter, Horizontal Diftance, and Height or Defcent of an Objeft, to find the Elevations of the Line of Direétion neceflary to hit the given Odjeét ; that is, having GM, M X, and thegreateft Random equal to half the Parameter ; to find the Angles FG B. Let the Tangent of the Angle fought be =#, the Horizontal Diftance GM=1, the Altitude of the Oljett MX ==h, the Parameter=ps and Radius —y, and it will be, | ?
As r.to t, fob toe 3 or Mh. 7 sie
qin afcents bei Xiaed !
in defcents
Lb — -% “a i : By | eee ee pb=Gh quad. aX ¥ quad ratione r : at 3g roy TES ret
Parable; but” ¥ hf bas TAO BO ¢ sian
b pet Ae ‘GL quad. 47: 1. Euclid. Wherefore a Tae Ns Bae ? ama he SKS
thd : + ph = bb Sate ‘ b hich ‘Equation trane
rs ; 0 Ae Me a ge at spe
fpofed, is aid: Meets bootie
ve bb pth spp bj divided by ib is Per r eG st | ue
‘ “x KS
Maifcellanea Curiofa. 319
t t __pt—?P h ar : ; = Magee 71. this Equation fhews the Que-
ftfon. to have 2 Anfwers, and the Roots there. . Le ay
of are = hier i aaa ie : ah 2h 4.bb 7 from which I derive the following Rule.
Divide half the Parameter by the Horizon- “tal diftance, and keep the Quote ; az. oe then fay, as /quare of the diftance given to the haif Parameter 5 {0 half Parameter 4- double
height oe
ee to the fauare of a Secant = rev ape
The | Tangent “anfwering to. that Secant, will be
V PP 4ph —t or Square of Radius, be!
fo esi the fum and difference of the afore- found Quote, and this Tangent will be the Roots of the Equation, and the Tangents of the Eleva- tun Toaghre ote orgs) | ot Svan
-\ Note here, that (in Defcents, if the “Tangent exceed the Quote, as it does when ph is more than bb, the direftion of the lower Elevation will be below the Horizon, and if ph=bb, it muft be direted: Horizontal, and the Tangent of the upper, Elevation will be a :. Note like-
wile, that if 4 bb’ 4, phin Afcents, or 4, bb— 4 ph in Defcents, be equal to pp, there is but one Elevation that can hit the Obje@, and its
?
Tangent i827. Andi A.bE 4. pb in Aleem,
of.
220 Mifcellanea Curiofa. — or 4.bb —4 pb in defcents, da exceed pes the Ob- ; jeét is without the reach of a Proje&t calt with that — Velocity, and fo the thing impothible. +
“From this Equation 4bb 4 4 ph == pp are de- © termined the utmoft limits of the reach of any © Proctt, and the Figure afligned, wherein are ie all the heights upon each Horizontal diftance beyond which it cannot pafs ; for by reduction — of that Equation, b will be found = 3 p— —
bh, b by G — in heights, and nae — ip in defcents ; from
whence it follows, that all the Points 4 are in — the Curve of the Parabola, whofe Focus is the Point from whence the Project is caft, and whofe Latus rettum, or Parameter ad Axem is =: p.” Likewife from the fame Equation may the leaft Parameter or Velocity be found capa- ble to reach the Objef? propofed ; for bb = 3 pp + ph being reduced, £p will be =
Bik MS aC tant in. afcents ek be Vie ae eee si which “is the | Hozontal Range at 4.5 degrees, of a Projet caft with the leaft Velocity that would juft reach the Ob- je@, and the Elevation requifite will be eafily had; for dividing the fo found Scmi-parameter by the Horizontal diftance given b, the Quote into Radius will be’ the Tangent. of the Elevation fought. This Rule may be of good ufe to all Bombardiers and Gunners, not only that they may ufe no more Powder than is neceffary, to caft their Bombs in- _ to the place afligned, but that they may fhoot with much more certainty, for that a {mall Error committed in the Elevation of the Piece, will produce no fenfible Difference in the fall: — ot :
_. Mifcellanea Curiofa. 321 Shot : For which Reafons the French Engineers in their late Sieges have ufed Mortar-pieces ins clin’d conftantly to the Elevation of 45, propor tioning their Charge of Pouder according to the diftance of the Oljeé# they intend to ftrike. on POs Sih ssiiiesish oT 1X ect _ And thi is all thar need to be faid con- cerning this Problem of fhooting upon Heights and Defcents. » But if. a Geometrical ConftruGi- on thereof ybe required; I. think I.,have one that. is as.eafy as can be expected, which I de- duce Tom. the foregoing Analytical Solutions
ps 7 gga a a cco and "tis thiss
having made the right Angle GDF, (Tab. 5° - Figs 3.) make DF = § p, or greateft Range, and GD. = the Horizontal Diftance, and DB ==h the perpendicular heighth of the Object ; to be laid upwards from D, if the Object be above the Horizon, or downwards if below it. Paral- del to GD draw FA, and make it equal to _GB the Hypothenufal Diftance of the Objet; and with the Center A and. Radius FB = ip “+b, fweep an Arch,. which fhall if the thing be -poffible, <interfe& the:indeterminate Perpendicular DF in two Points K and .L, to which draw she Lines, GL, GK; I fay, the Angles DGK, DGL,, are the) Elevations requilite to ftrike the Demonftration. ‘The Square of FK or FL, is ~ equal toF Bg—-GBa: or3p +h1*— bb — bb
ori pp pb — bb, and therefore V4 pp + ph —bb == FK = FL,<and by Confequence DK, awe isi SIS OE Sk ¥ thitas * DL
oe ewe Y oe $4
RRR s\n ae Pe | 322 Mifcellanea Curiofo, = DLeipt Viper i. Andas DG: DK and DL:: Radius: Tangents fought, — — ni ee with. our Algebraical Exprefiion — thereot. i “ 2 riPiee tie a M7 3 ae —— & i. - :
¥, ¥ w 3 4 Cl whine
Prop. XI. To determine the Force or Velocity ofa Prejelh in every Point of the Curve it de- feribes. A BROCE. TO: NSS ere
To do this'we need no other Pracognita, but only the third Propofition, viz. “That the’ Velo- ity of failing Bodies, is double to ‘that ‘which'i the fame time, would: have defcribed the Space — fallen by an equable Motion : For the Velocity of a Projedt, is compounded of the conftant equal Velocity of the impreffed Motion, and the Velocity — of the Fall, under a given An le, viz. the Com-
Jenient of the Elevation : For Inftance, in Fig. 2. in the time wherein a ProjeCt would move from - G to L, it defcends from ‘L to” X, and by the — third Propefition has acquired ’a Velocity, which in — that time would have carried ic by an equable © Motion from L to 'Z, or twice the Defcent'L X; and drawing the Line GZ, I fay, the Velocity in the Point X, compounded of the Velocities GL and LZ under the Angle G L Z, ‘is to the Velocity imprefs'd inthe Point G, as GZ is 19 GL ; this follows from our fecond Axiom, and — by the 20 and 21 Prop. lib. 1. conic. Midorgit, XO parallel and equal to GZ fhall touch the — Parabolain the Point X. So that the Velocisies — in the feveral Points, are as the lengths of the — ” Langents to the Parabola in thofe Points, inter- — cepted between any two Diameters « thefe
again are as the Secants of the Angles, which — thofe Tangents continued make with. the Horizon- ta Line GB. From what is here laid down, .
: may
MifielloncaCiviofe. 323 may the comparative Force of a Shot in any two Points of the Curve, be. either Geometrically ot Mrithmesically difcover'd. 3 off)
Corollary. —
From hence it follows, that the force of a Shot — is always leaft ar U, or the Vertcx of the Paras ola, and thap at equal diftances therefrom, as at _ Tand:X, Gand B itsforce is always‘equal, and ‘that the leaft force in U_ is to that in Gand B, as Radius. to the Secant of the: Angle of Elevation FG B. : , ~ Thele Propofitions confidered, there is no ques ‘ftion relating: to Projeéts, which, by the help of then, may not eafily be Solved’; and tho? it be true that moft of them. are to be met withal, in _ Galileus, Torricellius and others, who have taken them. from thofe Authors, yer their Books being Foreign, and not eafy to come by, and their De _monfirations long and difficult, I thought it not amifs to. give the whole De&rine here in Engl i fh, with fuch fhort Analytical Proof of my own, as might be fufficient to evince their’ Truth, . | The ‘Tenth Propofieton contains a Problem, une _ touch’d by Torricellius, which is of the greateft _ ufe in Gunnery, and for the fake of which this Difcourfe was’ principally intended.: Ie was firt Solved by Mr, Anderfon, in his Book of the Ges - nuine Ue and Effects of the Gun, Printed in the Year'1674 5 but his Solution’ required'fo ‘much Calculation, that it pur me upon fearch, whether. it-might'not be\done more eafily, and thereupon Am the: Year 1678 1 found our the Rule I now Publifh; and from it the Geometrical Conftru@tion = — Since which time’ there has a. large Treatife-of this — ¥2 Subjed
324 Mifcellanea Curiofa.
Subject, Inticuled, L’ Art dejctter les Bombesy been — y -Publifhed by Monfieur Blondel, wherein he gives.
the Solutions of this Problem by Meffieurs Buot, Romer and de la Hire: But none of them being the fame with Mine, or,.an my Opinion, more eafy, and goft of them more Operofe, and be- fides mine finding the Tangent, which generally determines the Angle better than its Sine, I thought my {ef obliged to Print it for the ufe ofall fuch,
as delire to be informed inthe Mathematical part
of the: Art of Gunnery.
_, Nowsthele. Rules were » rigidly true, were it —
nor, as I {aid before, for the Oppofition of the Medium,’ whereby not only the direct impreft Motion is continually retarded, but likewife the
incieafe! of the Velocity of the Fall, fo that the Spaces defcribed thereby, are not exatly asthe ©
Squares of the ‘Times: But. what: this Oppofition
of the-Air is, againft feveral Velocities, Butks,
and Weights. is not. fo eafie to determine, “Tis -
certain that the weight of Air to that of Water, is nearly as 1 to 800, whence the weight thereof,
to that of any Project is given’; “us very likely,
that to the fame Velocity and Magnitude, but’ .of different Matter, the Oppofition fhould be recspro: cally .as the weights of, the Shot 5. as likewife that to Shot of the fame Velocity and Matter, but of different Sizes, it fhould be as the Diameters reci= procally :. Whence generally the Oppofition to Shot with the fame Velocity, but of differing Diameters, and. Materials, fhould be as their Specifick:Gra- vities into their Diameters reciprocally. 5 but. whe-
ther the Oppofition, to dittering Velocities” of the
fame Shot, be. as the Squares of thofe: Velocities, or_as the Velocities themfelves, or orherwife, is yet a harder Queftion. : However it:be, tis cer- fade eS tain,
ui
Mifcellanea Curiofa. 325 tain, that in large Shot of Metal, whofe weight many Thoufand times furpaffes that of the Air, and whofe force is very great, in proportion to the Surface wherewith they prefs thereon; this Oppofition is fcarce dilcernable; For by_ feveral Experiments made with all Care and Circum{pecti- jon with a Mortarpicce, Extraordinary well fix'd to the Earth an purpofe, which carried a folid Brafg Shot of four Inches: and-a half Diamerer, and of. abour fourteen, Pound Weight, the Ran- ges above and. below forty five Degrees were found mearly equal; if there were any diflerence, the under Ranges went rather. the fartheft, but thofe — ’ differences. were ufually iefs than the Errors com- mitted? in ordinary Practice, by the unequa Goodnefs and Dryne’s of the fame fort of Pow- der, by, the Unfitnefs of the Shot to, the Bore, and by the Loofnels of the Carriage. ate Ina fimaller Brafs-Shor of about an Inch and half Diameter, caft by a Crofs-Bow which ran- ; ged it, at moft about four Hundred Foot, the Force being much more equal than in the Mor- terpiece, this difference was found more Curioufly : and Conftantly and moft Evidently, the under Ranges out-went the upper. From which Tri- als Lconclude, that a'thongh in {mall and light Shot, the Oppofition of the Air, ought and muft be accounted for ; yet in Shooting of great and weighty Bombs, there need be very little or no allowance. made; and fo thefé Rules may be put in practice to. all Intents and Purpofes, as if this Impediment were abfolutely remov’d. =
326 «©Mifcellanea Curiofa. "A Propofition of general Ufe in the Urb of Cite
nerys fhewing the Rule of laying a Mortar to (pals, in order to ftrike an Oljc& above or be-
dow the Horizon.
"Te was formerly the Opinion of thofé concerned in Artillery, that there was a certain requifite of Powder for each Gun, and that in Mortars, where the diftance was to be varied, it muft be done by giving a greater or leffer Elevation to the Piece. But now our later Experience has taught us that the fame thing may be more cer- tainly and readily performed by intreafing and diminifhing the quantity of Powder, heer ne ; gard be bad ‘to the Execution to be done, or to the Charge of doing it. For when Bombs aré difcharged with great Elevations of the Mortar, they fall too Perpendicular, and‘ bury themfelves too deep in the Ground, to do all that damage they might, if they came more Oblique, and breke upon or near the Surface of the Earth 5 which is a thing acknowledg’d by the Befieged in all Towns, who unpave their Streets, to let the Bombs bury themfelves, and thereby ftiflle © the force of their Splinters. A Second Conveni- ence is, that at the extream Elevation, the Gune ner is not obliged to be fo curious in the directi- on of his Piece, but it will fifice’ to’ be within 2 Degree or two of the Truth; ‘whereas in the ‘other Method of Shocting he er to be’ , eurious. Buta Third, and no lef confiderable Advantage is, in the faving the Prince’s Powder, which in fo great and fo numerous Difcharges, — as wehave lately feen, muft needs amount to a tonfiderable, Value.. And for ee it is
Se a eee
Mifcellanea Ca “377 featce practicable otherwife to ufe them, where _ the:agitation of the Sea continually changes the “Dire&tion of the Mortar, atid would render the “Shot! very uncertain, ‘were it not rhat they are _splaced about 45 Degrees Elevation, where feve- wal Degrees above or under, make very little dif eference in the BffeA. | pole » In the precedent Difcourfe, 1 confidered all ~ the Propofitions relating to the Motion of Pro- jeGtiles, and*gave a Solution to this Problem ; viz. ‘Tobit an Objet above or below the Horizontal Line with the preateft Certainty and leaft Force. : ‘is, that the Horizontal diftance of the Object be- ing put =, and the Perpendicular Heighth == b, the Charge requifite to ftrike the Object with the greateft Advantage, was that which ‘with an Elevation of 45° would caft the Shot on the Horizontal Line, tothe diftance of ¥ bb + bhy when the Object was above the Horizon ; or _ if ic. were below ir, the Charge muft be leffer, fo as to reach on the Horizon, at 45? Elevation, no greater a Diftance than Vob -+ bb ens ; that is; in the one Cafe, theSum of the Hppe- thenufal Diftance of the Obje& from the Gun, and the Perpendicular Heighth thereof above the Gun ; and in the other Cafe, when the Object 4s below the Horizon, the difference of the fame per 47. 1 Eucl. And I then fhew'd how to find the Elevation proper for the Gun fo charged, viz. As the Horizontal Diftance of the Obje&, to the Sum or Difference of the Hypothenufal Diftance and Perpendicular Height: So Radius ta the Tangent of the Elevation fought. But I was hot at that: time aware that aa aforefaid Elevation Yo ; 4 did
323 «© Mifcellanea Curiofa. ) did conftantly bifec&t the Angle-between the Per- _ pendicular and the Object, as is demonftrated — Ha the Difference and Sum of the Tangent and Secant'of any Arch being always equal to the Tangent and Cotangent of? the half Complement thereof to a Quadrant. . Having difcovered ‘this, I think nothing can be more compendious, or bids — fairer to compleat the Art of Gunnery, it being as eafie to fhoot with a Mortar at any Object on — demand, as if it were on the Level; neitker-is there need of any Computation, but only fimply ‘laying the Gun to pafs,in the middle Line bee — tween the Zenith and’ the Objet,’ and giving it its due Charge. Nor is there any great need of © Inftruments for this purpofe: For if the Muz- ale of the Mortar’ be turned truly. Square tothe Bore of the:Piece,, as it ufually,is or ought to be, a piece.of Looking-glafs Plate applied parallel to the Muzzle,’ will by its Reflection give the crue Pofition of the Piece, the Bombardeer having no — more to do, but to look perpendicularly down — on the Looking-glafs,. along a {mall ‘Thread with a Plumbet, and to raife or deprefs the Ele- vation of the Piece,’ till the Objeét appear re- flected on the fame Point. of the Speculum,’ on which the Plumber falls ; forthe Angle of Inci- dence and Reflection being equal, in this Cafe a — Line at Right Angles to the Speculum, as is’ the Axis of the Chafe of the Piece, will bifect the
"Angle between the Perpendicular and the: Ob-
Ie, according at our Propofidon, requires °So_ ‘that it only ‘remains. by good and.valid Experi- -ments to’ be aflured of the Force of Gunpowder, how to.make and conferve it equal, and to know
he. Effe& ‘thereof in each Piece; that is, how
of
Mifcellanea Curiofa. 329 -of it; which may moft conveniently be engra- ven on the outfide thereof, as a ftanding Dire@i- oa to all Gunners, who fhall from thence for- ward have occafion ta ufe that Piece: And were this Matter well afcertained, it might be worth ‘the while to make all Mortars of the like Dia- meter as near as may he, alike in length of Chafe, Weight, Chamber, and all: other Cir- ‘cumftances. é | . - This Difcovery that the utmoft Range on an — inclined Plane, is, when the Axis of the Piece makes equal Angles with the Perpendicular and the Object; compared with what I have demon ‘trated of the fame Problem in the aforefaid Dif. courfe does lead to and difcover two very ready ‘Theorems ; the one, to find the greateft Hori- zontal Range at 45° Elevation, by any Shot made upon any inclined Plane, with any Eleva. tion of the Piece whatfoever : And the other to find the Elevations: proper to ftrike a given Obe ject, with any Force greater than what fuffices to ‘reach it with the aforefaid middle Elevation, Both which being performed by one fingle Pro- _ portion, may be very ferviceable to fuch as are concerned in the Practice of Gunnery, but are _ unwilling to trouble themfelves with tedious and ‘difficult Rules. The two Propofitions are thefe.
PROP. L
. A Shot being made on an inclined Plane, ha- ‘wing the Horizontal’ Diftance of the Objet it trikes, with the Elevation of the Piece, and the Angle at the Gun between the Obje& and the Perpendicular; to find the greateft Horizontal Rangeof that Piece, laden with the fame Charge; foe that
330 «© Mifceilanea Curiofa, that is, half the Larus redum of all the Parabole made with the fame Imperusy 9
* * i z, z 5 z 4 > Da &
Take half the Diftarice of the Obje& from the Nadir, and take the Difference of the:given Elevation from that half ; the Verfed Sine of twice that Difference fubtra& from the Verfed Sine of the Diftance of the Objet from the Zenith: ‘Then fhall the Difference of thofe Verfed Sines: be to the Sine of the Diftance of the Obje& from the Zenith, as the Horizontal Diftance of the Ob-— ject ftrook, to the greateft Horizontal Range
at phe Seeee eH aie . ee
" ofRO! Padloe «nest Ineo
+4
. Having the greateft Horizontal Range of 2 Gun, the Horizontal Diftance and Angle of In- clination of an Objeét to the Perpendicular, to find the two Elevations neceflary to ftrike that
3 | Donates ee BOIEAY Aor
a , Ree | i Wee Tee :
Flalve the Diftance of the Objet from the Nadir; this half is always equal to the half Sum of the two Elevations we feck. Then fay, As the greateft Horizontal Range is to the Horizon- tal Diftance of the Objett: So is the’ Sine of he Angle of Inclination or Diftance of the Object from the Perpendicular, to a fourth Proportional 5 which fourth being fubtratted from the Verfed Sine of the Diftance of the Object from the Zenith, leaves the ‘Verfed Sine of she Difference: of the Elevations
a Sought 5
Mifcellanen Curiofe. 331 fought 3 which Elevations are therefore bad by ad- ding and fabtraing the half Difference to and from the afore{aid half Sum.
J fhall not need to fpeak of the Facility of thefe Solutions, I {hall only obfrve that they are doth General, without Exception or Caution, and derived from the Knowledge that thefe two ‘Elevations are equidiftant above and below the Line, bifeéting the Angle between the Object and the Zenith. ih
332 Mifcellanea Curiofa. | |
Srey ie
A Difcourfe concerning the Mea- '. fure of the Airs Refiftance to Bo- dies moved init. By the Lear- _ ned John Wallis, S.Z. D. and
re HAT the Air (and the like of any other Medium) doth confiderably give Refiftance to Bodies moved in it ; and doth there- by abate their Celerity and Force ;) is general- ly admitted. And Experience doth atteft it : For otherwife, ‘a~ Cannon-Bullet ~proje&ted Ho- rizontally, fhould (fuppofing the Celerity and Force undiminifhed) ftrike as hard againft a Perpendicular Wall, erected at a great di- {tance, as near at hand ; which we find it doth Ok. |, : 2. But at what Rate, or in what Proporti- on, fuch Refiftance is; and (confequently, at what Rate the Celerity and Force is continual-— ly diminifhed) feems not to have been fo well examined. Whence it is, that the Motion of a Projeét (fecluding this Confideration) is com- monly reputed to defcribe a Parabolick Line ; as arifing from an Uniform or equal Celeri- ty.in the -Line of Projection, anda Celerity — uniformly accelerated in the -Line of Defcent; which two fo compounded, do create a Para-
bola. : :
Wea Ser’ Es aoe
3- In
Mifcellanea: Cuviofs. 223
9. In order to the Computation hereof, I firft premile this Lemma, (asthe mott rational that doth occur for my firft footing,) ‘That (fuppofing other things equal) the Refiftance is proportional to the Celerity.. For in a double-Gelerity, there is to be removed (in the fame time) twice as ‘much Air, (which is a double Impediment) i in 4 treble, thrice as much; and fo in other Propor- tons.
4. Suppofe we then the Force impreffed (and bntiseienly the Celerity, if there were no Re- fiftance) as 1 ; the Refiftance as r. (which muft be lefs than the Force, or elfe the Force would not prevail over the Impediment, to create a Motion.) And therefore the effective Force at ‘a firft Moment, is to be reputed as r— 7: That 4s, fo much as the Force imprefled, is more than athe Impediment or Refiftance. - | 5: Be it as r—r to 1; fo one to m. (which © m is therefore greater than 1.)
6. And therefore the effective Fotce (and sconfequently. “a Celerity) as to.a firlt Mo- ment, i is to be won of what ‘it would be, ‘had
ew ‘there bees: no Fe Giance.
7: “This ag is alfo the remaining Force af-
‘ter fuch firft Moment : ; and this remaining Force is, (for the fame Reafon) to, be proportionally vabated ws 10a fecond, Apnea 3 that is, we. are
‘to take — ——“thereof, that is’ of the impref- mm
“ea Force. “And so @ third Moment > equal
Aiftance of time) ———,; for a fourth 53, and
fo pager infinitely. a 8. Becaufe
334 “ Mifstlaiee Carafe, : pe fe Becaufe the length difpatched (in equal times) is proportion sods Coe Are Emap af aren seg to thofe sqant Kime) are
tks as =, So op op Ga of. what. they
would as anand 3 in the fame Times bad ese) been no Refiftance.
g. This therefore is. 2, Geometrical Pinca on; sf ae of m tae thea q) Sn ly decreafing. .
10. This. decreafing. Progreflion finely continued (determining in the fame Point of Reft, where the Motion is fuppofed to ex- pire) is yet of a finite, Magnitude ; and equal to oy of what it would have been in fo mi— much Thue. f there had been no Refiftance. As is demonftrated. in my Algebra, Chap. 25%
Prop. 8. For: (as 1 have: elfewhere demonftra- ted) the Sum or Aggregate of a Geometri=
cal Progreffion is — aay fuppofing v the
greateft Term, 4 the leat, and R- aa ae
mon Multiplier.) That. is eres <a Now in the prefent Cafe, (fappofing the» Pro- greflion infinitely’ continued) the leaft Term
4, - becomes infinitely fmall, or =o. . And confguenly a d doth, alfo vanith, and the ¢-
by: the. Aggregate becomes = FB Perth ae
— Mifeellanen Curiofa. 335 VV &e,
- (as will appear by dividing RW RORR ‘omy
PRO R15) rp <— Lab eee ay Poy an te ee: ote enh ¥ ‘ edie? pat ee if 33 RK. 2 ik ; : i Vo — bh oe sauieaionealin RR R? R—i? +7 R ¢ fuppofing the Progrefion — vi Ge | to begin at V==1.) That is Oe Gividing all by & that fog the Progrefion may begin * (ES a rv dd ae ee kee ORE +—+ Sc, Thatis, mour . Ma oak prefen¢ Cafe (becaufe of + 1,8 Rm) ty t Be Coe ante Ge
es GS Le | : eed &e. = ——. That is, (putting 2 = m—1) — mint’ a
of what it would, have been if there had been no Refiftance. I MS. 11. This infinite Progreffion is fitly expref- fed by an Ordinate in the Exterior Hyperbola, parallel to one of the Afymptotes; and the feveral. Members of that, by the feveral Mem- bers of this, cut in continual Proportion. As is there démonftrated at Prop. 15. For let $ , (uid. Fig. 4. Tab. 5.) be an Hyperbola be- tween the Afymptotes 4B, AF: And let the Ordinate DH (in the Exterior Hyperbola, pelle to. AF,) reprefent the imprefled Force ndiminifhed ; or the Line to be defcribed infuch time, by a Celerity anfwerable to fuch undimi- nifhed Force, And let BS (a like Ordinate be thereof; which therefore, being lefs than D# (as being equal to a Part of it) will be larthes Mh she. - that
*
3 ab. Mifeellanea Curidfa.
than it from AF. In AB (which I put = 1) ' let Bd be fuch a Part thereof, as is BS of DH. 4% Now becaufe (as is, well known) all the inferi- — bed Parallelograms, i in the Exterior H: yperbola, AS, AH, &e. are equal ; 3 and therefore, their |
fides reciprocal : Therefore asAd == — Pa ;
(fuppofing Bd to be taken, from B tae 4; SD to AB =1, (or as m—, 1 to mi be is BS”
is foe isn. H, to m—1) (a arty tee : m m? : db, which is non zit ae pe therefore equal 4 ic aay » tne ne I A ig , } 3 ‘ to——— of DH; Te pom d: id that . 4s (as . will : Are f Bi by divi- -~ SNEED ose Soe appear A vi- ‘3 , a he ing war : iia tala ym > om Seti og — 1,) to—+ : ccm cme TH 131 ) pe TT Sapteg ett ; SOT HREEL Fae : aE i —<. ve mm, me of PHM: Or if BE: WG taken beyond B;
then a Adi
rch to Abs ot 7s (Wergeibs ¢
Ta i. svt ee - mm foe I tos My ‘Pi~ ie OS =a te hthes ee esa ;
= Ty or as
sihich is + therefor equal t to—
DH; > “chat is | by. like, aviding ‘f I by. m adi 1; i
| (as will appear
pt ta = Ba of DH.
=O mm oe
| 144 {
—Mifcellanea Curiofa. 337
12. Let fuch ordinate d4, or (equal to it in the Afymptote) 4F, be fo divided in L, M, N, @c. (by Perpendiculars cutting the Hyperbola in ‘i,m,’ 2, Ge.) as that FL, L.M, MN, beas | aaa ea —;, &c. Thar is, focontinually de- , ms mm? om , crealing as that each Antecedent be to its Confe-
SETS ees ae, ; ; quent, ast 10 "—~, or as mto t. See Fig. 5. Tab. 5+
4 '23.) This isdoneby taking 4 F, AL, AN, Ges in fuch proportion. For, of continual Propor- tionals, the Differences are alfo continually pro- ‘portional, and in the fame proportion. For let A, B, C, D, Gc. be fuch Proportionals, and their _ Differences a,b,c, €c. hat is, A—B==z, B—C=), C—D, =¢, Ge.
_. Then, becaufe A, B,C, D, &c. are in conti- nual proportion,
Pete ae A Be BC: C.D: e+ And dividing A—B.B:: B—C.C:: C—D D:: &c. | ‘That is, oP 3: b,Gsrd. Ds: Se. . And alternly — A bec €50,.<- B.C]. te. 2: | A. B. Cc. Fc. : |
That is, in continual proportion as Ato B, or as m to 1. ;
14 This being done; the Hyperbolick Spaces _ Fl, Lm, Mn, &c. are equal, As is demon- {trated by Gregory San-Vincont ; and as fuch is commonly admitted. . 15. So that F/, Lm, Mn, &c. may fitly re- prefent equal Times, in which are difpatched unequal Lengths, reprefented by FL, L M, MN, Hole Z | 16. And
338 Mifcellanea Cariofs.
16. Ned ect they are in Number infinite ©
(though equal to a finite Magnitude) the Dura- tion is infinite: And confequently the imprefled
PN Fe calle
Force, and Motion thence arifing, never to be wholly extinguifhed (without fome further Im-— pediment) but perpetually approaching to 4, in
the Nature of Afymprtotes.
17. The Spaces F/, Fm, Fn, &c. are there- '
fore as Logarithms (in Arithmetical Progreffion — tncreafing ) anfwering to the Lines AF, AL,
AM, &c. or to FL, LM.,MNy, &e. in aes
metrical Progreflion decreafing. | 18. er FL, LM, MN, &c. are as
Bi oSa ——y 5» —so, XC. Genital) terminated at mim m?
pe
A; therefore (by Sih 10) their Aggregate FA or dh, isto D H, (fo much Length as would have been difpatched, in the fame time, by fuch im- prefled Force undiminithed} as 1tom—1 =
1g. If therefore we take, as 1 to m, fo 4E
‘to DH; this will reprefent the Length to be di-
fpatched, in the fame time, by fuch undimithed Force.
20. And if fuch DH be fuppofed to be divi. ded into equal Parts innumerable (and therefore infinitely fmall ;) thefe anfwer ‘to thofe ee cies Parts unequal in F 4, or hd.
21. But, what is the Proportion of + to 1, or (which depends on it) of r—rto 1, or 1 co a remains to be inquired by Experiment ? |
22. Ifthe Progreflicn be not infinitely continue ed ; butend (fuppofe) at ip and its ee Term be
1 fas = he ak —,
A=M N; then, out of
0. is ta be fubdudted i (as at J 10.) thats
(as
Mifcellanea Curiofa. 339 t : ‘f “4 : A A A _(as by Divifion will appear) ce nt RE ~h ine
| th Ca a That is (i fent Cafe) ——-+- — + That is (in our pre! ) ae a
Hi I—a [—,g
&c. And fothe Aggregate will be
And thus as to the Line of ProjeGtion, in which (fecluding the Refiftance, the Motion is re- puted uniform ; difpatching equal Lengths in e- qual Times. Confider we next the Line of De- {cent. '
23. In the Defcent of Heavy Bodies, it is fuppofed that to each Moment of Time, there is fuperadded a new Impulfe of Gravity to what was before: And each of thefe, fecluding the Confideration of the Air’s Refiftance, to proceed equally (from their feveral beginnings) through the fucceeding Moments. As (in the ere& Lines)
4011; Ge 111, eo. 11, Fe.
1, &c. and fo continually, as inthe 1 Line of Proje@tion. rr.
_ 24. Hence arifeth (in the tran 1117 _verfe Lines) for the firft Moment 111 t ‘1, for the fecond 1 -+ 1, for the co ° third t+ 1 + 1, and fo forth,
‘in Arithmetical Progreffion: As are the Ordi-
nates in a Triangle, at equal. diftance. _ 25. Aad fuch are the continual Increments of the Diameter, or of the Ordinates in the exterior Parabola, anfwering to the interior Ordinates, or Segments of the ‘Tangent, equally increafing ; as is known, and commonly admitted.
(he he - 26. 1F
CRIS SS ree ae Pe ee a
240 Mifcellanea Curiofa.
26. Jf we take in the Confideration of the — Air’s Refiftance; we are then, for each of thefe — equal Progreflions, to fubftitutea decreafing Pro- — greflion Geometrical ; in like manner (and for — the fame Reafons) as in the Line of ProjeCtion.
27. Hence arifeth, for the
firft Moment — ; for the fe- sx 3
I
. m
I I a Lory cond —- -- —; for thethird —,—
bid] Mm m?* m
I I I ea ee
fuch is therefore the Defcent 1 r 1 JT of a heavy Body falling by its he ee on
ownweight. The feveral Im- : pulfes of Gravity being fuppofed equal. 28. That is (in the Figure of § 12) as FL, FM, FN, &c. in the Line of Defcent, anfwer- ing to FL, LM, MN, &c. in the Line of Pro- jection. aes! cat} 29. But though the Progreffions for the Line: of Projeétion, are like to each of thofé many in the Line of Defcent ; it is not to be thence inferred,
that therefore + in the one, is equal to in the other « Be fa the Line of Projection (fup- pote) f (fuch a Part of tee Force impreffed, and a Celerity anfwerable :) in the Line of De- {cent, a g fucha Part of the Impulfe of Grae
vity. | sae ie 30. Thofe for the Line of Defcent (of the fame Body) are all equal, each to other: Becaufe
| | g (the
ae
NS EM aig aE oN), A Ap ser
Mifcellanea Curiofa. 341 g (the new Impulfe of Gravity) in each Moment is fuppofed to be the fame.
31. But what is the Proportion of f to g (that of the Force impreffed, to the Impulfe of Gra- vity in each Body) remains to be inquired by Experiment. |
32. This Proportion being found as to one known Force; the fame is thence known as to
any other Force (whofe Proportion to this is gi-
ven) in the fame uniform Medium.
22. And this being known, as to one Medium ; the fame is thence known as to any other Medi- ‘um, the Proportion of whofe Refiftance to that of this is known.
24. If a heavy Body be projected downward in a perpendicular Line; it defcends therefore at
the Rate “e ae Jc. of f (the impref-
mm fed Force) increafed by —,— +4 —,— + mm om m?’ m ny I sa Tera wy Sc. of g the Impulfe of Gravity, me om
(by 4 7, and € 27) Becaufe both Forces are - here united.
35. If in a perpendicular Projection upwards;
it afcends in the rate of the former, abated by that of the latter. Becaufe here the Impulfe of Gravity is contrary to the Force imprefled. |
36. When therefore this latter (continually increafing) becomes equal to that former (conti- nually decreafing) ic then ceafeth to afcend; and doth thenceforth defcend at the rate wherein the latter continually exceeds the former.
37. In an Horizontal, or Oblique Projection : |
-Ifto a Tangent, whofe Increments are as FL,
342 Mifcellanea Curiofa. . Sl mcs) 3 a
I | ;
LM, MN, &c. that is as——f, &c. be fitted — in ‘ Bh
Ordinates (at a given Angle) whofe Increments —
‘ oS BM i are as FL, FM, FN, &c. thatis, as——g, &c.
The Curve anfwering to the Compound of thefe - Mottons, is that wherein the Projet is to move.
38. This Curve (being hitherto without a Name) may becall’d Linea Projeétorum ; the Line - of Projects, or things projected ; which relem- bles a Parabola deform’d. oe : 39. The Celerity and ‘Tendency, as to each | Point of this Line, is determined by a Tangent” at that Point. . 4 40. And that againft which it makes the grea= teft Stroke or Percuiiion, is that which (at that Point) is at right Angles to that Tangent. ar. If the Projeétion (at $27.) be not infi- nitely continued, but terminate (fuppofe) at N, {> that the laft Term in the firft Column cr Se~ ries ere&t be 23 and confequently in the fecond, ma. in the third, mma, &c. (each Series ha- ving one ‘Term fewer than that before it:) Then _ (for the fame Reafons, as at € 12.) the Aggre- gates of the feveral Columns (or ere& Series) wilhe = ons eo ar =e ita and fo forth, n n n ee a ;
till (the Multiple of 2 becoming = 1) the Pro« greflion expire.’ : gr 42. Now all the Abatements here, 2, mas mma, &c. are the fame with the Terms of the ft Column taken backward. For @ is the daft, ma the next before it; and fo of the "Pelee: Ree >. ¢ : g ) 43. And
a ae erage ier ate
— Mifcellanea Curiofa. 343 43. And the Aggregate of all the Numera- tors is fo many times 1, as is the Number of Terms (fuppofe ¢,) wanting the firft Column ;
4 I—a nt—I+a - that is -— ——,
; and this a- or oe
gain divided by the common Denominator x, be- nt—I--+a
nn
nt—1-ka
&
comes And therefore
is the Line of Defcent by its own Graviry. 44. If therefore this be added to a proje&t-
ing Force downward in a Perpendicular; or
fubducted from fuch projeGting Force up-
e I — @ ward ; that is, to or from ———f: The D.. ae 2
s
bb | ‘ iw {cent in the firft Cafe will be | : f+ nt—I--ka : :
ETT -g 3 and the Afcent in the other Cafe Oil et @ nt—I1-ka
g. And in this latter
n - mn Cafe, when the ablative Part becomes equal to the pofitive Part, the Afcent is at the higheft ; and thenceforth (the ablative Part exceeding the -pofitive) will defcend. ~ 4§- In an Horizontal or Oblique Projection,
ag f, in the Line of Projection,
having taken n Ni~—=1 a
C
y and thence (at the Angle given)
“in the Line of Defcent; the Point in the Curve anfwering to thefe, is the Place of the Project anfwering to that Moment.
Z 4 4.6. I
¥ s
344 Mifcellanea Curiofa.
46. I am aware of fome Objections to be made, whether to fome Points of the Procefs, — or to fome of the Suppofitions, But I faw not — well how to wave it, without making the Com- putation much more perplex’d! And in a Mat- ter fo nice, and which muft depend upon -Phyfi- cal Obfervations, *twill be hard to attain fuch Accuracy, as not to ftand in need of fome Allow- ances. oe _ 47. Somewhat might have been farther added
to direct the Experiments fuggefted at 9 21,and — 21. But that may be done at Jeifure, after de- liberation had, which way to attempt the Expe- riment.. | i
48. The like is to be faid of the different re- filtance which different Bodies may meet with in the fame Mrdium, according to their different Gravities (extenfively or intenfively confider’d) and their different Figures and Pofitions in Mo- tion. Whereof we have hitherto taken no ac- count ;. but fuppofed them, as to all thefe, to be alike and equal. |
P: 05S. T SG.R LRT hloe AQ. The Computation in @ At, 425 435
may (if thar be alfo defired) be thus. reprefented by Lines and Spaces. ‘The Ablatives 2, may,
mma, &c. (being the fame with the firft Co-
lumn taken backward) are fitly reprefented by the Segments of NF (beginning at.N) in Figure 5 and 6, and therefore by Parallelograms on thefe - Bafes, affluming the common height of FA, or NQ; the Aggregate of which is NA,. or FQ. And, fo many times'1, by fo matiy equal Spaces, on the fame Bafes, between the fame Parallels,
7 terminated
ile ea ; - : aia — Mifcellanea Curiofa. 345 terminated at the Hyperbola: The Aggregate of which is bh FNQn, - From whence if we fub- duct the Aggregate of Ablatives FY; the re- ‘maining Trilinear } Q x, reprefents the Defcent,
_ ¥9. If to this of Gravity, be joined a project ing Force; which is to the Impulfe of Gravity as as b K to hF (be it greater, lefs, or equal} ta- ken in the fame Line; the fame Parallels deter-
_ mine proportional Parallelograms, whofe Agere-
gate is KQ. ee ,
51. And therefore if this be a perpendicular Projection downwards; then b K kn (the Sum of this with the former) reprefents the Defcent.
gz. If it be a Perpendicular upwards ; then
the difference of thefe two reprefents the Motion ; which fo long as KQ is the greater, is Alcen- dent ; but Defcendent, when b Qn becomes greater 5 and it is then at the higheft when they
be equal. bay 36 -§3- If the Proje&tion be not in the fame Per- ‘pendicular, (but Horizontal, ’ or Oblique) then
_KQ reprefeats the Tangent of the Curve ; and
“hb Qn the Ordinates to that Tangent, at the gi- een Anele. | tt | |
_., 54. But the Computation before given, Itake
to be of better ‘ufe «than this Reprefentation in
“Figure. Becaufe in fuch Mathematical Enqui-
‘Ties, I choofe to feparate (as much as may be
“what purely concerns Proportions; and confider
“it abftra@ly from Lines, or other Matter where-
“with it is incumbred. ;
As to the Queftion propofed ; whether the re- fiftance of the Medium do not always take off fuch a proportional part of the Force moving through it, as is the fpecifick Gravity of the Me- dium to that of the Body moved in it: on
by
6 iio fo, it will fave. us the trouble of Obferva- tion.)...
I think this can by no means be admitted. For —
% 4 ie
there be many other things of Confideration here-
Gn, befide the intenfive Gravity (or, as fome call it, the fpecifick Gravity) of the Medium.
A vilcous Medium fhall more refift, than ;
one more fluid, though of like intenfive Gra- —
vity.
eafily through the Medium, than a, blunt-headed
Bolt, though of equal Weight, and like intenfive ;
Gravity.
And the fame Pyramid with the Point, than |
with the Bafe forward. pee
And many other like Varieties, intended. in .
my ¥ 48.
But this I think may be admitted, namely, i That different Mediums, equally liquid, (and o- ther Circumftances alike,) do in fuch proportion
refift, as is their intenfive Gravity. Becaufe there is, in fuch proportion, a heavier Object to
be removed, by the fame Force. Which is one
of the things to which § 33 refers.
And again: The heavier be as once in Mae
: all other Cir- cumitances alike). moves through the fame Meds= um in fuch proportion more ftrongly, as is its in- tenfive Gravity. For now the Force is in fuch proportion greater, for the removal of the fame yefitance. And this Part of what my § 32 in-
tion, (being equally fwift, an
finuates..
Hut)
And a fharp Arrow fhall bore his way more !
Mifcellanea Curiofa. 347 But where there isa Complication of thefé
Confiderations one with another, and with many other Circumftances, whereof each is feverally
to be confidered ; there muft be refpect had to
all of them.
Ce mr eh RAN ARE TEENY STV LEDER TITLE I NT TT OEE NF ESSE CMTE IE
348 | Mifcellanea Curiofa,
An Inftance of the Excellence of the Modern Algebra, in the Refolu- tion of the Problem of finding the
Foci of Optick Glaffes Univer- fally. By. Halley, S.R.S.
HE Excellence of the Modern Geometry —
is in nothing more evident, than in
thofe full and adequate Solutions it gives to
Problems; reprefenting all the poffible Cafes at one view, and in one-general Theorem, — many times comprehending whole Sciences ; ‘which deduced at length into Propofitions, —
and demonftrated after the manner of the Ancients, might well become the Subjects of —
large Trreatifes: For whatfoever ‘Theorem folves the moft complicated Problem of the — kind, does with a due Reduétion reach all the —
fubordinate Cafes. Of this I now defign to give a notable Inftance in the Doétrine of © Dioptricks. da Wi ne. i” This Dioptrick Problem is, that of finding — the Focus of any fort of Lens, expofed either — to converging,* diverging, or parallel Rays of — Light, proceeding from, or tending to a gie ven Point in the Axis of the Lens, be the Ra- — tio of Refraétion what it will, according to the © Nature of the tranfparent Material whereof — the Lens is formed, and alfo with allowance — for the thicknefs of the Lens between the Ver-
tices
Peewee a rere va Oe
Mifcellanea Curiofa. 349
tices of the two Spherical Segments. ‘This Pro-
blem being folved in one Cafe, mutatis mutane
_ dis, will exhibit Theorems for all the poffible Cafes, whether the Lens be Double-Convex or ‘Double-Concave, Plano-Convex, ‘or Plano-Concaves or Convexo-Concave, Which fort are ufually call’d Menifsi. But this only to be underftood of thofe Beams which are-neareft to the Axis of the Lens, fo as to occafion no fenfible difference by their Inclination thereto; and the Fecus here formed, is by ‘Dioptrick Writers commonly call’d the principal Focus, being that, of ule in Tele/copes and Microfcopes. i
Let then {in Fig. 7. Tab. 5.) BE& be a dou- ble Convex Lens, C the Center of the Seg- ment’ EB, and K the Center of the Segment -E@, B& the thicknefs of the Lens, D a Point in the Axis of the Lens; and it is required to find the Point F, at which the Beams proceed- ing from the Point D, are collected therein, the Ratio of RefraGtion being as m ton. Let the diftance of the Objet DB=DA=d (the Point ~A being fuppofed the fame with B, but taken at a diftance therefrom, to prevent the coin- cidence of fo many Lines) the Radius of the Segment towards the Object CB or CA==7, and the Radius of the Segment from the Ob- ~ ject K4 or K=e; and let B& the thicknefs of the Lens be ==, and then let the Sine of the Angle of Ineidence DAG be to the Sine of the refracted Angle HAG or CA@ as m ton: And in very {mall Angles, the Angles themfelves
will be in the fame proportion ; whence it will _
follow that,
ha ae ee Oe
350 Mifcellanea Curiofa. | As dtor, fo the Angle at C to the Angle at D, and d-tr will be as the Angle of Inci- dence GAD; and again asm to , fo d-+r to PN og eee 4 ee which will be as the Angle GAH= CAe; This being taken from ACD which
m—nd—nr
is as dy Will leave analogous to the
m ‘Angle AgD; and the Sides being in this Cafe proportional to the Angles they fubtend, it will follow, that as the Angle A@D is to the An- gle AD®, {o is the’ Side AD or BD to Age ac Bey That ts, Bo wilt tee ee, m—nd—nr
which fhews in what Point the Beams proceed- ing from D, would be collected by means of the firft Refraction ; but if mr cannot be fubftracted_ from m—n d, it follows that the Beams after. Refragtion do ftill pafs on diverging, and the. Point @ is on the fame fide of the Lens beyond D. But if nr be equal to m—nd, then they praceed parallel to the Axis, and the Point 9 is infinite-
ly diftant.
The Point @ being found as before, and Be—-Bé being given, which we will call J, it follows by a Procefs like the former, that @F, or the focal Diftance fought, is equal to i’ lt tan lhl =f And in the room of #
m—d-- m ¢ ) fubfticuting Be—B FP eee " m—nd—nr
» after due Reduétion this fol-
lowing
ting p for
n A ed
— Mrfcellanea Curiofa. 251 lowing Equation will arife, | !
é mpdrommndet—enpret
mdr + mdg—mpre—m—ndt-hurt moe Which Theorem, however it may feem operofe, is not fo, confidering the great Number of Dare that enter the Queftion; and that one half of the Terms arife from our taking in the thicknefs of the Lens, which in moft Cafes can produce “no great Effec& ; however it was neceflary to con- fider it, to make our Rule perfect. If therefore the Lens confit of Gla/s, whofe Refraction is as Zto2 "twill be RELCS se arin a =f lf
% —Bdrt+-3d¢—6re—drt-are ate of WVater,whofe Refraction is as 4.to 3, the Theorem
will ftand thus 124" $—3¢er-orer _ Adr-FAde—trzre— dirt =f. If it could be made of Diamant, whole ‘RefraGtion is as § to 2, it would be 3 We dre—rdpittrer ‘FS drb ¥dem——4°re—2dt+arz saat And this is the univerfal Rule for the Foc; of double Convex Glaffes expofed to diverging Rays.’ Buc if the thicknefs of the Lens be rejected, as not Aenfible, the Rule will be much “fhorter, ize
‘eden de = f, or in Glafs Birkin lh adr de—prt dr-- de—2rp
‘=f, all the Terms wherein + is found being o-
mitted, as equal to nothing. In this Cafe, if 4 be fo fmall, as that 27¢ exceed dr ~+ de, then -will ic be —f, or the Focus wi'l be. Negative, which fhews that the Beams after both Refracti- ens {till proceed diverging.
CEST) Se eee Bt + ct eva oie Su Wipe Sed Cea ta &
352 Mifcellanea Curiofa. — To bring this to the other Cafés, as of con-— verging Beams, or of Concave Glaffes, the Rule is ever compofed of the fame Terms, only chang- ing the Signs of -+- and — ; for the diftance of the Point of Concourfe of converging Beams, from-the Point B, or the firft Surface of the Lens, | call a negative Diftance or — d; and the Radius of a Concave Lens I call a negative Radius, or — +r if it bethe firft Surface, and: — e, if it be the fecond Surface. Let then converging Beams fall on a double Convex of Glafs, and the Théo- —a2dre if Ae oe: —dr—de— 2 RN Ts which fhews that in this Cafe the Focus is always affirmative. | Ria Ve If the Lens were a Menifcus — of Glafs, expoed to diverging Beams, the Rule is —2dre ad ; —dr +de-2re when 2 r ¢islefs than d+ —d ¢, otherwile negative: But in the Cafe of converging Beams falling on the fame Menifeus, “twill be fallestnait ehh : - “hdr—deturp — f, and it will be +f, whilft de — dr is lefs than ; are; butif itbe greater than 2re, it will always be found negative or—f. If theLens be doubleConcave, the Focus of converging Beams is negative, where it was affirmative in the the Cafe of diverging Beams —2dre 7. +drtde—a2are — f, which is affirmative only when 2 7 ¢ exe ceeds dr -— d¢: But diverging Beams pafling a double Concave, have always a negative Fo-
—2dre | ——__—_— = —f,
CHS, VARs —+drRhdebure aK
rem will ftand thus
=f, which is affirmative -
- on a double Convex, vz.
¥ ¢
a
Mifcellanea Curiofa. 355 The Theorems for converging Beams, ar principally of ufe to determine. the Focus refulting from any fort of Lens placed in a Telefcope, be- tween the Focus of the Object-Glafs and the Glafs it felf ; the diftance between the faid Focus of the Object-Glafs, and the interpofed Lens being made = — d. _ There fuppofe my Reader acquainted with the Rules of Analytical. Multiplication and Di- fion, as that -+ multiplied by + makes the Produ& -k, -- by — makes —-, and — by — makes -+; fo dividing + by -+ makes the Quote ++, + by —makes—, and — by — makes “=F; which will be neceflary to be underftood in the preceding Examples. a In cafe the Beams are parallel; as coming from an infinite diftance, (which is fuppofed in the Cafe of Telefcopes) then will d be fuppoféd Infinite , and in the Theorem pder Ar td g—pre being finite, which is no part of the other inf- nite Terms; and dividing the Remainder by the infinite Part d, the Theorem will ftand 2 48
the Term p r ¢ vanifhes, as
per ° thus = f,or in Glafs —f, eur fs eee ff. In cafe the Lens were Pleno-Convex expofed _to diverging Beams, inftead of- HE Ain Be a, d r being infinite, it will be! F =i) fy OF eae. : if the Lens be Glafs. d= 2 ¢
: If the Lens be Double-Convex, and + be equal ta ¢, as being formed of Segments of ‘f | Aa equal
356 Maifcellanea Curiofa. .
der
equal Spheres, then will 3 |
: ‘ ‘ FR sik ed pdr
reduced to pee f ; and in cafe d be infi-
nite, then it will yet be farther contratted to
n
2 pv, and p being = the fucal diftance
m— Ny in Glafs will be = 7, in Water 1 % 7, but in Diamant 3 7. | : Iam fenfible that thefe Examples are too much for the compleat Analyft, though I fear. too little for the lefs Skilful ; it being very hard, if poffible, in fuch Matters, fo to write, as to give fatisfaction to both; or to pleafe the one, and inftruét the other. But this may fuffice to fhew the extent of our Theorem, and how eafie a ReduGtion adapts any one cafe to all the reft. i Ee RD Nor is this only ufeful to difcover the Focus from the other propofed dara, but from the Focts given, we may thereby determine the diftance of the Objet ; or from the Focus and Diftance- given, we may find of what Sphere itis requi- fite to take another Segment, to make any given Segment of another Sphere caft ’ the Beams from the diftance dto the Focus f. As likewife from the Lens, Focus, and Diftance given, to find the Ratio of Refraction, or of m to my requifite to anfwer thofe Dara, All which it is obvious, are fully determined from the Equation we have hitherto ufed, ~zz. pagr=drf+def — pref, for to find 4
Peels The Theorem is —-—_——_—_— = d, the rf ines 6 fap ae
diftance of the Object. For
Mifcellanea Curiofa. | 357
: ay, ae ie Fore the Rule Pete ed bap <sioms, Oe
: aa preidef 7 Butfor p willbe = pylage sg eee
latter determines the Ratio of Refraction, m being to mas I -F p to p:
I fhall not expatiate on thefe Particulars, but leave them for the Exercife of thofe that are defirous to be informed in Optical Matters, which I am bold to fay are comprehended in thefe three Rules, as fully as the moft Inquifitive scan defire them, and in all poflible Cafes ; regard being had to the Signs -- and —, as in the former Cafes of finding the Focus. I fhall only fhew two confiderable Ufes of them ; the one to find the diftance whereat an Object being plac’d, fhall by a given Lens be reprefented in a Species as large as the Objeétit felf, which may be of fingular Ufe in drawing Faces and other things in their true Magnitude, by tranfmitting the Species by a Glafsinto a dark Room, which will not only give the true Figure and Shades, but even the Colours themfelves, almoft as vivid as the Life. In this Cafe d is equal to f, and fub- ftituting d for f in the Equation, we fhall have pdr gaz ddr --+-dde — dp ¢r, and di- viding all by dpre—mdr—-+d e— pr ¢, that is,
which
2. r e e ee Be Pe, d 5 but if the twe Convexities be of ) ee ae
the fame Sphere fo as r = ¢, then will the di- ftance be = pr ; that is, if the Lens be Gla = 27, fo that if an Object be placed at the Diameter of the Sphere diftant, in this Cafe the Fens will be as far within as the Objeét is
Aaz with
353 Maifcellanea Curiofa. without, and the Species reprefented thereby will be as big as the Life ; but if it were a Plano-Convex, the fame diftance will be = 2 Pr or in Glafs to four times the Radius of the Convexity ; but of this Method I may enter- tain the Curious at fome other Time, and fhew how to magnifie or diminifh an Object in any proportion aflign’d, (which yet will be obvious enough from what is here deliver’d) as likewife how to ere&t the Obje& which in this Method 1s repre- prefented inverted. ; at A fecond Ule is to find what Convexity or Concavity is required, to make a valtly di-e ftant Objet be reprefented at a given Focus, after the one Surface of the Lens is formed ; which is but a Corollary of our Theorem for finding ¢, having p, d, r and f given; ford
being infinite, that Rule becomes = ; amit that is in Glafs Beate =: e, whence if f be Zrmf ia
greater than 2 7, ¢ becomes Negative, and —
ah fe , j
Thofe that are wholly to begin with this -Dioptrical Science, cannot do better than to read with Attention a late Treatife of Diop- tricks, publifhed by 1% Molineux, Efg, R.S. S. who has at large fhewn the Nature of Optick Glaffes, and the Conftruétion and Ufe of Mi crofcopes and Telefcopes ; and though fome nicely Critical have endeavour’d to {py Faults, and to traduce the Book ; yet having long fince examin’d it with Care, I affirm, that if I can judge, it hath but two things that with
is the Radius of the Concave fought. i :
359
Mifcellanea Curiofa. 3 59
any Colour may be call’d Faults; the one, an over-careful acknowledgment of every* Trifle the Author had receiv’d from others ; and the other that he labours to make eafie this curious Subject, fo little underftood by moft, in a manner perhaps too familiar for the Learned Critick, and which demonftrates that it was writ cum animo docendi, both which require but very little Frienfhip or good Nature in the Reader, to pafs for Vertues in an Author. i
But to return to our firft Theorem, which accounting for the thicknefs of the Lens, we will here again refume, viz.
mpdre—nagtt np ret Lule
mdr-mdemmpr¢—m—ndt-tnrt
And let it be required to find the Focus where a whole Sphere will collect the Beams proceeding from an Objet at the diftance a: Here ¢ is equal to 2 r, and 7 equal toe. And after due Reduétion, the Theorem will ftand thus,
mpdr—aundrrrunprr _,. :
Meee 4s Ol py pica but if d be mpr
%
Infinite, it’ is contracted to
a, y (a a
aT LE ag f, wherefore a Sphere of Glafs 2m —202-
collects the*Sun-Beams at half the Semi-diametet of the Sphere without it, and a Sphere of War ter at a whole Semi-diamerer. But if the Ratio of Refra€tion m to n be as 2 to ty the Focus falls on the oppofite Surface of the Sphere ; but if it be of greater Inequality it falls within.
Aa 4 Another
260 Mifcellanea Cuviofa.
Another Example fhall be when a Hemi-
fphere is. expofed to parallel Rays, that is, d_
and ¢ being infinite, and ¢ = 7, and after due
Reduction the Theorem refults———"_ r = .
mm—-mn That is, in Glafs it is at 47, in Water at 4 75 but if the Hemifphere were Diamant, it would collect the Beams at 1 +# of the Radius beyond the Center.
Laftly, As to the Effect of turning the two fides of a Lens towards an Objet; it is evident, that if the thicknefs of the Lens be very {mall,fo as that you negleét it, or account = 0 ; then in all Cafes the Focus of the fame Lens, to whatfo- ever Beams, will be the fame, without any diffe- rence upon the turning the Lens : But if you are ~ fo curious as to confider the thicknefs, (which is feldom worth accounting for) in the Cafe of pa- rallel Rays falling on a Plano-Convex of Glafs,
if the plain fide be towards the Object, ¢ does ©
occafion no difference, but the focal diftance f= 2,r.. But when the Convex-fide is towards the Object, it is contraéted to 2r— 4+, fo that the Focus is nearerby #2. If the Lens be double
Convex, the difference’ is lefs ; if a Menifcu,
greater. If the Convexity on both fides be equal, the focal length is about }¢ fhorter than when #=0. In a Menifcus the Concave-fide to- wards the Cbje& increafes the focal Length, but the Convex towards the Object diminifhes it. A General Rule for the difference arifing on turning the Lens, where the Focus is Afhir- zrt—2et
mative, is this i ark se—e’
for double
Convexes of differing Spheres. But for Me- nifcs
Mifcellanea Curiofa. 361 Menifci the fame difference becomes 2 peek 2 er “a igamelilee eae lg other Demonftration,but that by a due Reduction it will fo follow from what is premifed, as will the Theorems for all forts of Problems relating to the Foci of Optick-Glafles |
; of which I need give no
Aa4 A P-
APPENDIX.
( 365 )
An Analytical Refolution of certain Equations of the Third, Fifth, Seventh, Ninth Powers, and fo
_onad Infinitum, in finite Terms, after the manner of Cardan’s Rules for Cubicks, By Mr. A. Moivre, Tranfat?. N°. 309.
ET (n) be any Number, (») an unknown Quantity, or Root of the Equation, (a) a ‘Quantity altogether known, or what they call Homogeneum Comparations : And let the Relation of thefe Quantities to each other be expreft by the Equation. | :
nni=tT (2 ome
wet BO wg ang” ans nu——Q nun—2F 7 : : Amt ah eects 23 4X5 6%7 Rats Hens Its plain from the Nature of this Series, that if » be any odd Number (that is an Integer, it matters not whether Affirmative or Negative) then the Series will ‘Terminate, and the Equa- tion arifing will be one ‘of the above defind, _ whofe Root is
74
nn—I
(nye
266 Mijfcellanea Curiofa.
j sg ———====—— ee (ny tV Vi-baata— ° z or, J i-baaha
eee al 28 yarn (2)y 22 VV trae ha Vee Ofs
(2)9== VV 1taa—a
(ye VV itaa—e VV tanta For Example, Let the Root of this Equation of the Fifth Power be required 5 y -+- 20 y3 -
1695 = 4. in which cafe n is = 5, and a = 4, and the Root, according to the firft Form, is
L ——R—F_ ———— v —3\/V 1+aa—a or,
= 1VVi7-e4 “he 2 which is Ex- . V i974 | peditioufly refolved into Numbers after this man- ner. : | , | Vy7-+4 is equal to 8.1231, whofe Loga-
rithm is 0,9097164) and the fifth part of it is is 051819433, the Number anfwering it
P5402 == V/V 17-4. But the Arithmetical Complement of 0.6577 is 9.8180567 , the ) 3 i
Number anfwering is 0.1819433 = ign V19-F4, and the half difference of thefe Numbers is 0.4313 — 7: | Here
Mifcellanea Guriofa, 367 Here we may obferve, that in the Room of the general Root, we may advantageoufly take
z
ymitVoar— if the quantity a be pretty
a 24
large in refpe& of Unity. As if the Equation ~ were §y + 2073 -F 1675682, the Logae rithm of 2 4 = 3.1348143 whofe Fifth part is 0.6269628, the Number anfwering is 4.236, and the Number anfwering the Arithmetical Complement 9.3730372 is 0.226, the half dif. ference of thefé Numbers is 2 = y.
But if in the aforegoing Equation the Signsare alternately Affirmative and Negative ; or which is the fame thing if the Series be after this “Manner, — 3 | War Se Ee oe To, § Om 12 N 7 Moe Mh er ey Foe 2X2 22 OARS | in n 7 o-—-nn 25—uNn
ano ax 6X7 The Root of ic will be equal to
ny
eed i gy (epee crt + ——_—__—_————-, or
A ne aac gemma Vee aati CYTE Sis ERA SSRIS es n iaesaiee j (2) yt atV aa—i-Ft Va—V aa—l, or
Xx . 8 ; I Sai ol ee anles Wee. a—TJ, OF
\ poly A-——T
£
z
rd a ” : Berd VN a— a a1 fa V a—Tf
os Here
368 Mifcellanea Curiofa,
a2 1
Here it is to be noted, that if be an
2
odd Number, the Sign of the Root found muft
be contrary to it. Let an Equation be propos’d 5 y — 207 3-& 165 = 6, whence n == 5, and 4 = 6, and the 6) oes pee : Root will be == £\/6-+Y 35 + a Oe ag
becaufe 6 --§ V 35 = 11.916 whofe Logarithm is 1.0761304, and its Fifth part is 0.2152561, whofe Arithmetical Complement is, 9.7847429. ‘The Numbers belonging to thefe Logarithms are 1.6415 and 0.6091, whofe half Sum is 1.1253 == 9, | But if it happen that a is lefs than Uniry then
the Second Form, as being more convenient, — ought to be pitch’d on. So if the Equation had: Fa :
been 5 y-— 2073 - 16y5= aq? then y will
Pe
64 4096 * 64 . 4096
- and if the Root of the Fifth Power can by any means be Extracted the true and poflible Root of the Equation, will thence Emerge, tho’ the Expreffion feems to infinuate an_Impoflibility. But the Root of the Fifth Power of the Binomial
bese a's af 37S ig = M15 and fo the {ame Root of the Binomial. |
V—15 the half
‘Sum, of which Roots is =
I
64 — 40996 4 & oe But
ace ut
Mifceilanea Curiofa, 369 But if that Extra@ion can not be perform’d, or may feem too difficult, the thing may be folv’d by the help of a Table of Natural Sines, after the following manner ;
To the Radius 1 let 2 = a = 0,95112 the Sine of fome Arch which is therefore 72° 23’, whofe Fifth part (becaufe is equal to 5) is 14? 28! the Sine of it is 0.24981 == = nearly.
The fame is the Method of proceeding in _ Equations of higher Dimenfions.
»
a STINE
oa
i 3 t SEE, © ge oN a¥
aot
Nae
(a1)
A Difcourfe concerning the Acfion of the Sun and Moon on Animal Bodies ; and the Influence which This may have in many Difeafes. By Richard Mead, M. D.
F, R. S. P AOR TT.
HAT fome Difeafes are properly the Effects ay of the Influence of the Heavenly Bodies, and that others do vary their Periods and Sym- ptoms according to the different Pofitions of one or other of thofe Luminous Globes, is a very an- cient and certain Obfervation. -Upon this {core _ Hippocrates (a) advifes his Son Theffalus to the ftudy of Geometry and Numbers, becaufe the Knowledge of the Stars 4 of very great ufe in Phy- fick (b). And the earlieft Hiftories of Epidemic Diftempers, particularly do all turn upon the alterations made in our Bodies by the Heavens.
But when in later Times Medicine came to be accommodated to the Reafonings of Philofopherss: no body being able to account for the manner of this Celeftial AGtion, It was allowed no fare ther fhare in affeCting our Health, than what might be inaputed to the changes in the manifeft Conftitution of the Air, excepting perhaps fome-
Bb thing
(a) Epift. ad Theffalum Filium. | (b) "Oux éraaxicoy peers oun Barrelar ‘“Asepvonta eis “Inzermny. De Aere Aquis & Locis.
372 Mifcellanea Curiofa. thing of Truth which ftill remains difguifed and blended with the Jargon of Judiciary Aftrology.
In order therefore to fet this Matrer in a lit- tle clearer light, I fhall in the firft place thew, That the Sun and Moon regarding their Near- nefs and DireCtion to the Earth only, befides the Effects of Heat, Moifture, @c. thereby caufed in our Atmofphere, muft at certain times make fome Alterations inall Animal Bodies; then enumerate fome Hiftories and Obfervations of fuch Changes, and enquire of what Ufe fuch Thoughts as thefe may be in the Practice of Phyfick.
It is a conftant Obfervation of thofe who write the Hiftory of the Winds, That the moft Windy Seafons of the Year, are the Time about the Vernal and Autumnal Equinox; for be the Air never fo calm before or after, we never fail of having Winds at that Jun@ure. Every body likewife knows, that in the moft quiet Weather we are fure of fome Breeze at Mideday and Mid- night, as alfo at Full Sea, 7. e. always about the time the Sun or Moon arrive at the Meridian. Seamen and Country People reckon upon This, and order their Affairs accordingly. And tke changes of the Weather as to Winds or Calms efpecially about the New and Full Moon, are too well known to require any Authority to con- firm fuch Remarks. Thofe who defire a fuller account of thefe Obfervations, may fee it in De Chales’s Navigation, Gaffendus’s Natural Philofo- phy, and F. Goad, his Aftro- Meteoro- Logica.
Thefe things being Matters of Faé&, and ina Manner Regular and Univerfal, ic may very well feem {trange that Philofophers have not been more accurate in their Enquiries into the Reafon of {uch Appearances. Tue indeed itis, that the _ Origin of Winds is various and uncertain, but however
Mifcellanea Curiofa. 373 however, fo conftant and uniform an Effe€ muft ~ undoubtedly be owing to one neceflary Caufe.
It has bin, now a confiderable time fince, fufficiently made out, that our Atmofphere is a thin Elaftic Fluid, one part of which gravitates upon another, and whofe Preflure is communt- cated every way in a Sphere to any given Part thereof. From hence it follows, ‘That if by any external Caufe the Gravity of any one part fhou’d be taken off or diminifhed, that from all fides ae round this part, the more heavy Air would rufh in to reftore the Equilibrium which muft of ne- ceflity be preferved in all Fluids. Now this violent running in of the heavier Air would cers
tainly produce a Wind, which is no more than a ftroag Motion of the Air in fome determined Dire&tion. If therefore we can find any outward Caufe that would at thefe {tated Seafons we have mentioned, diminifh the Weight or Preflure of the Atmofphere ; we fhall have the genuine Rea- fon of thefe Periodical Winds, and the necef- fary Confequences thereof.
The Flux and Reflux of the Sea was a Phee- nomenon t90 vifible, and too much condu- cing to. the Subfiftance of Mankind, and allo- ther Animals, to be negle&ted by thofe who ap- plyed themfelves to the Study of Nature, howe ever all their Attempts to explain this Admirable Contrivance of infinice Wifdom were unfuccefsfull, cill Sir Ifaac Newton reveal’d to the World jutter Prin- ciples, and by a truer Philcfophy than was formerly known, fhew’d us how by the United or Divided Forces of the Sun and Moon, which are encreaf- ed and leflened by feveral Circumftances, al! che Varieties of the Tides are to be accounted for. And fince all the Changes we have enumerated ‘in the Atmofphere do fall out at the fame times Bb 2 when
ees | ey H 374. Mifcellanea Guriofa. when thofe happen in the Ocean ; and likewife whereas both the Waters of the Sea and the Air of our Earth, are Fluids fubje&t, in a great Meafure, to the fame Laws of Motion ; it is plain, that the Rule of our great Philofopher takes place here, viz. That Natural Effeéts of the fame kind are owing to the fame Caufes. (a) What difference that known Property of the Air, which is not in Water, makes in the Cafe, . I fhall fhew anon; fetting afide the Confiderati- on of that for the prefent; It is certain, ‘That as the Sea is, fo muft our Air, twice every 25 Hours, be rais’d upwards to a confiderable height, by the Attraction of the Moon coming to the Meridian; fo that inftead of a Spherical, it muft form it felf into a Spheroidal, or Oval Fi- gure, whofe longeft Diameter being produced, would pafs thro’ the Moon. That the like Rai- fing muft follow as often as the Sun is in the Me- ridian of any Place, either above or below the Horizon. Moreover, That ‘this Elevation is’ . greateft upon the New and Full Moons, becaufe both Sun and Moon do then confpire in their Attraction ; /eaf? on the Quarters, in that they then drawing different ways, ‘tis only the Diffe- rence of their Actions produces the Effect. Laft- ly, That this Intumefcence will be of a middle degree, at the time between the Quarters, and New and Full Moon. | From the fame Principles, The Motion up- wards of the Air will be ftrongeft of all about the Equinoxes; the Equinoctial Line being over that Circle of the Globe, which has the greateft Diameter, either of the Luminaries when in that | are
(4) Newton, Princip, pe 402+
of
_ Mifcellanea Curiofa. 37 are nearer, and the Agitation of the Fluid Sphe-
roid revolving about a greater Circle, is greater;
belides, the Centrifugal Force (arifing from the
_ Diurnal Rotation) is there greateft of all. This will ftill be more confiderable about the New
and Full Moons happening at thefe times, for the Reafons juft now mentioned. And the leaft Attraction will be about the Quadratures of thefe
Lunar Months, becaufe the Declination of the Moon from the Equator is then greateft. * The
different diftances of the Mcon in her Perigeum and Apogeeum, are the Reafon that thefe full changes fall out a little before the Vernal, and after the Autumnal Equinox. Now the Inverfe of all this happens when the Luminaries are in the Solftitial Circles. | Laftly, In the fame Pa- rallel, when the Moon’s Declination is towards the Elevated Pole, the Attraction is ftrongeft when the Moon is in that Places Meridian, and weak- eft when fhe is in the Oppofite Places Meridian: The contrary happens in the Oppofite Parallel ; by reafon of the Spheroidal Figure of the Earth and its Atmofphere. | Whatever has been faid on this Head, is no more that applying what Sir I/aac Newton has De- monftrated of the Seato our Atmofphere ; and itis needlefs to fhew how neceffarily thofe Appears ances, juft now mentioned, of Winds, at the Stated Times, €c. muft happen hereupon. It will be of more ufe to confider the Propor- tion of the Forces of the two Luminaries upon the Air, to that which they have upon the Wace ter of: our Globe 3 that it may the more plainly appear what Influence the Alterations hereby made, muft have upon the Animal Body. |
Bh 3 : Sis
376 Mifcellanea Curiofa. Sir Ifaac Newton has demonftrated (a) That
the Force of the Sun to move the Sea, is to the
Force of Gravity, as 1 to 12868200. Let that be :
S.G::1.n. Hence, Gib n
And that the Force of the Moon to raife the Sea is to Gravity, as 1 to 2031821. Let this be ° ;
L.G:: 1. s. Hence, pe
$ | And fince the Centrifugal force of the Parts of the Earth arifing from its Diurnal Motion is to Gravity, as 1to 291. Let this be
‘CoG #2 WC. Den Cee od Mende, Ff é€
I M4 al S+L.C — —-+-- —, —; — -—-— aa 2 n $ é iii 1: 1, 6031 sFnmXe :
The fame Philofopher has taught us (4) that the Centrifugal force raifes the Water at the Equator above the Water at the Poles, to the height of 85200 Feet, Wherefore if that Force which is as 6031, raife the Ocean to 85200 Feet, the United forces of the Sun and Moon, which are as 1. will raife the fame to 14 Feet,
si
ele) - for —— = 14. Proximé.
Now
(a) Princip. Lib. 3. Prop. 36. (bd) Ibid. Lib. 3. Prop. 37+
Mifcellanea Curiofa. 3:77
Now we know that the more eafily the Was _ ters can obey the Attraction, with the more Force are the Tides moved; but fince, as Mr. Halley _ has determin’d it, (a) our Atmofphere is extend- ed to 45 Miles, whereas the middle depth of the Ocean is but about half a Mile ; it is plain, that the Air revolving in a Sphere about 100 times larger than that of the Ocean, will havea proportionably greater Agitation.
Befides, Rocks, Shelves, and the inequality of Shoars are a great ftop tothe Accefs and Re- cefs of the Sea: But nothing repels the rifing ~ Air, which is alfo of fuch tbinnefs and fluidity, that it is eafily driven, and runs every way. |
Nor ought we to omit, that ir is the univers fal Law of Bodies Attracted, that the Force of AttraGtion is reciprocally as the Squares of their Diftances; fo that the Action of the Sun and Moon will be greater upon the Air than upon the Water, upon the Account of its Near- eis.
But the Confideration of the Elafticiry is ftill of greater Moment here, of which this is the nature, that it is reciprocally as the Preffure, fo that the incumbent Weight being diminifhed by the AttraGtion, the Air underneath will upon this {core be mightily expanded.
Thefe and fuch like Caufes will make the Tides in the Air to be much greater that thofe of the - Ocean; nor is it neceflary to our purpofe to de- terminé, by nice Calculations, their particular Fortes ; it is fufficient to have proved that thefe Motions muft both be Univerfal, and alfo return at certain Intervals.
Bb 4 Now
(a) Pbilof. Tranf. N° 181.
378 Mifcellanea Curiofa.
Now fince the raifing of the Water of the O- © cean 14 Feet, produces Torrents of fuch a pro-— digious Force, we may eafily conceive what Tempetts of Winds (if not otherwife check’d) the Elevation of the Air much higher (perhaps a-_ bove a Mile) will neceffarily caufe. And there is no doubt to be made, but that the fame infi- nitely Wife Being, who contrived the Flux and ~ Reflux of the Sea, to fecure that vaft Colleétion © of Waiers from Stagnation and Corruption (which would inevitably deftroy all the Animals and Ve- getables on this Globe) has ordered this Ebb and Flood of the Air of our Atmofphere, with the like good defign, that is to preferve (in Cafe all other Caufes fhould fail,as they may, andat times do in — fome Countries) the fweet Frefhnefs, and brisk Temper of this Fluid, fo neceflary to Life, and keep it, by a kind of continual Circulation, from Deadnefs and Stinking. |
This Reafoning is liable to only one Objeéti- on that I know of, and that ts this: That the Appearances we have mentiond cannot be ow- ing to the Caufes now affigned ; fince by Cal- culation from them, the Mercury muft at New and Full Moon fubfide in the Barometer to a eertain degree, which yet we do not obferve to happen. Wf
In anfwer to which, (befides that there have been — fome Obfervations made of the finking of the — Mercury at thofe times ; and it may perhaps be — the fault of the Obfervers that thefe have not been —
reduced to any Rule) We are to Confider, ‘That
altho’ Winds and Alterations in the Preffure of
the Atmofphere, are the neceflary confequents of —
the Lunar Attraction, and true Cafés of the dif-
ferent Rife of the Mercury in the Barometer; yet
thefe may be produced many others ways sah A ea ae
Mi/fcellanea Curiofa. 279° and therefore tho’ regularly the Mercury would always fall at the New and Full Moon, thofe other Caufes may be {trong enough, even to raife ir at thofe Seafons; in as much as two con- trary Winds, for inftance, blowing towards the Place of Obfervation, may accumulate the Air there, fo as to increafe both the height and weight of the incumbent Cylinder; in like manner, the Direction of twoWinds may be fuch,as meeting at certain Angle they may keep the Gravity of the Air in the middle place unaltered ; and a Thou- fand fuch Varieties there may be, by which the Regularity of Appearances of this nature may be hindered. Now the other Springs, from which {uch Changes in the Air may arife, are thefe.
1. Elaftic Vapours forc’d from the Bowels of the Earth, by Subterraneous Heats, and con- denfed by whatever caufe in the Atmofphere.
' 2. A mixture of Effluvia of different quali- ties in the Air, may by Rarefactions, Fermen- tations, Jc. produce Winds and other Effeéts like thofe refulting from the Combination of fome Chymical Liquors; and that fuch things happen, we are aflured from the Nature of Thun- der, Lightning, and Meteors. |
_ 3.From the Eruptions of Vulcanoes and Earth- quakes in diftant Places, Winds may be propa- gated to remoter Countries.
4. The divided or United Forces of the other Planets and of Comets, may varioufly difturb the influence of the Sun and Moon, &c. We know
that there happen violent ‘Tempefts in the upper
Regions of the Air, while we below enjoy a Calm ; and how many Ridges of Mountains there
are onour Globe, which interrupt and check the
Propagation of the Winds ; fo that it is no won-
athe Mie : der
,380 Maifcellanea Curiofa.
der that the Phenomena we have afcribed to the A@tion of the Sun and Moon, are not always con- : ftant and uniform, and that every Effect does not hereupon follow ; which, were there no other Powers in Nature able to alter the influence of this, might in a very regular and uniform man- ner be expected from it. :
Thefe things being premifed, it will not be | difficult to fhew (as was propofed in the firft Place) that thefe Changes in our Atmofphere at High Water, New and Full Moon, the FEqui- noxes, €4c. muft eceafion fome Alterations in all Animal Bodies; and that from the following Confiderations. |
1. All living Creatures require Air of a de- termined Gravity to perform Refpiration eafily, and with Advantage ; for it is by its weight that this Fluid infinuates it felf into the’Cavity of the - Breaft and Lungs. Now the Gravity, as we | have proved, being leffened at thefe Seafons, a {maller quantity only will infinuate it felf, and’ this muft be of fmaller force to comminute the Blood, and forward its Paflage into the left Ven- tricle of the Heart, whence a flower Circulati- on infues, and the Secretion of Spirits is dimi- nifhed. a | | |
2. This Effect will be the more fure, in that the Elafticity of the Atmofphere is likewife di- minifhed. Animals want Air as heavy fo Ela- ftic to a certain degree; For as this 1s by its weight forced into the Cavity of the Thorax in Infpiration, fo the Mafcles of the Abdomen prefs s+ into the Bronchi in Expiration, where the bend- ing force being fomewhat taken off, and Springy | Bodies when unbended, exerting their Power ¢- —
| very
Mifcellanea Curiofa. 381 very way, in Proportion to their Preffures, the Parts of the Air pufh againft all the fides of the Veficule, and promote the Paflage of the Blood.
We have a convincing Inftance of all this, in thofé who go to the top of high Mountains, for the Air is there fo pure (as they call it) thar is, _ wants fo much of its Gravity and Elafticity, that they Breath with very great difficulty. |
3. All the Fluids in Animals have in them a mixture of Elaftic Aura, which when fet at li- berty, fhews its Energy, and caufes thofe Fermen- tations we obferve in the Blood and Spirits: Now when the Preflure of the Atmofphere, up- on the Surface of our Body is diminifhed, the’ inward Air in the Veffels muft neceffarity be in- abled to exert its Force, in Proportion to the leffening the Gravity and Elafticity of the out- ward; hereupon the Juices begin to ferment, change the Union and Cohefion of their Parts,
break their Canals, ec. ,
This is very plain in living Creatures put into the Receiver, exhaufted by the Aire-Pump, which always {well as the Air is more and more drawn out; their Lungs at the fame time contracting themfelves,and falling fo together as to be hardly difcernible, (a)
E’re we proceed to Matters of Fact, it may be worth the while to take Notice, That Effects depending on fuch Caufes as thefe, muft of ne- ceffity be moft vifible in Weak Bodies and Mor- bid Conftirutions, when other Circumftances con- cur to their.taking Place. For this reafon, whate ever Mifchiefs do hence follow, cannot in the
leaft
(a) Efperienze dell Academia del Cimento, p.m. 113¢
282 — Mifcellanea Curiofa. leaft difparage the Wife Contrivance of Infinite Power in ordering thefe Tides of our Atmofphere. ~ The Author of Nature, we know, has. made all things to the greateft Advantage that could be, for the whole Syftem of Animals on our Globe, — but it was impoflible that fuch a difpofition fhou’d - not in fome Cafes be prejudicial toa Few. The Pofition and Diftance of the Sun are fo adjulted, as to give in the moft beneficial manner poflible, Heat and Light to the Earth; yet this notwith- {tanding, fome Places may be too hot for fome weakly Bodies ; fome Autumns too fultry to a- ree with fome Animals, and fome Winters too cold to be endured by fome tender Creatures : The whole however we muft own, is moft care- fully provided for.- Befides, as moft of thefe laft mentioned Inconveniencies are by eafy fhifts to be avoided ; fo there are fuch Powerful Checks - put to this Aereal Flux and Reflux, fo many ways of abating the Damages accruing from it now and then ; that thefe are of no account in comparifon of the mighty Benefits hence arifing, in which the Race of Mankind does univerfally
fhare.
PART
pe (393°)
PPR Tok
TTCHERE are no Hiftorys in Phyfick which 5 iy we may more fafely take upon the Credit of the Authors who relate ’em, than fuch as we are now going to mention. In fome Cafesa Point may perhaps be ftrained to ferve a darling Hypothefis which the Writer bas taken up, but here we are much more likely to have pure Mat- ter of Fat, becaufe hitherto no one has pretend- ed the Appearances of this kind to be within the Reach of aigy Scheme of Philofophy, Epileptical Difeafes befides the other Difficul: tys with which they are attended, have this alfo furprizing, that in fome the Fits do conftantly return every New and Full Moon; the Moon (fays Galen (a) governs the Periods of Epileptic Cafes. Upon this fcore, They who were thus affected were called Seawzexol (b) and in the Hiftorys of the Gofpel SeanviaZéueyor (c) by fome of the Latins afterwards, Lunatics (d). Bartholin (e) tells a Story of one Epileptic who - had apparent Spots in her Face, which ac- cording to the Time of the Moon, varyed both their Colour and Magnitude.
But POA Da ae ee ee
(a) Tas tay extanaloy tne reebSes. De Diebs Critic. lib. 3. |
(b) Alexaud. Trallian, lib. 1. ¢, 15.
(c) Matth. c.17- v. 16.
(d) Apuleius de Virtutib. Herbar. cap. 6. 8 9s.
(e) Anatom. Centur, 2, H.72. *
384 Mifcellanea Curiofa.
But no greater Confent in fuch Cafes was perhaps ever Obferved than what I faw fome time fince in a Child about § years old, in which the Convulfions were fo ftrong and fre- quent, that life was almoft defpair'd of, and by Evacuations and other Medicines very difh- cultly faved. The Girl, who was of a lufty full habit of Body, continued well for a few days, but was at Full Moon again feized with a moft vio- lent Fit, after which, the Difeafe kept its Periods conftant and regular with the Tides; She lay always Speechlefs during the whole time of Flood, and Recovered upon the Ebb, ‘The Father who lives by the Thames fide, and does bufinefs up- on the River, obferved thefe Returns to be {¢
punctual, that not only coming a knew |
how the Child was before he faw it, but in the night has rifen to his Employ, being warned by Cries when coming out of her Fit, of the turn- ing of the Water. This continued 14 days, that is, to the next great Change of the Moon, and then a dry Scab on the Crown of the Head, (the effet of an Epifpaftic Plaifter, with which I had
covered the whole Occiput in the beginning of:
the Illnefs) broke, and from the Sore, tho’ there had been no fenfible Difcharge this way for a- bove a Fortnight, ran a confiderable quantity of limpid Serum ; upon which, the Fits returning no more, I took great care to promote this new Evacuation by proper Applications, with defired Succefs, for fome time ; and when it ceafed, be- fides two or three Purges withMercurius Dulcts, &C. ordered an Iffue in the Neck, which being thought troublefome, was made in the Arm; the Patient however has never fince felt any Attacks of thofe frightful Symptoms.
: ‘ Whether
Mifceilanea Curiofa, 385
Whether or no it be thro’ want of due Heed and Enquiry that we have not inall the Collections of Hiftories and Cafes, any Inftance of the like Nature fo particular as this is, I know not ; this is cer- tain, that as the Vertigo is a Difeafe nearly rela- ted to the Epilep[y, and the Hy/terical Symptoms do partake of the fame Nature; fo both one and the other are frequently obferved to obey the Lunar Influence. In like manner, the raving Fits of Mad People, which keep Lunar Periods, are generally in fome degree Epileptic too, ~ Tulpius (a) and Pifo (b) afford us remarkable Inftances of Periodical Palfeys.
Every one knows how great a fhare the Moon has in forwarding thofe Evacuations of the weaker Sex, which have their Name from the conftant Regularity they keep in their Returns 5 and there is no. queftion to be made, but the Corre- {pondency we here obferve, would be greater ftill, and even Univerfal, did not many Acci- dents, and the infinite Varieties in particular Con- ftitutions one way or other concur to make a dif- ference. It is very obférvable that in Countries _neareft tothe A.quator, where we have proved the Lunar Action to be ftrongeft ; thefe Monthly Se- cretions are in much greater quantity than in thofe near the Poles, where this force is weakeft. This Hippocrates (c) takes notice of, and gives it as one Reafon why the Women in Scythia are not very fruitful.
The Cafe being thus with Females,it is no wonder if we fometimes meet with Periodical Hemorrhages an{wering
(a) Obferv. Med. lib. 1. cap. 12. (b) De Morb. a ferofa Cokuvie, Obf. 28. (c) De Aere Aquis 5 Locis.
386 Mifcellanea Cuviofa. anfwering to the times of the Moon in Males ale fo. For as a greater quantity of Blood in pro- — portion to the bull in one Sexsis the reafon of its — difcharging it felf thro” proper Ducts, at certain Intervals, when the preffure of the external Air being diminifh’d, the internal 4ura can exert its — Elafticity; fo in the other, if at any time there” happens to be a Superabundancy of the fame Fluid, together with a weak Tone of the Fibres; it is plain that the Veflels wili be moft eafily burft, when the Refiftance of the Atmofphere is leaft. And this more efpecially, if any accidental hurt, or rarefying Force has firft given occafion to the other Caufes to take effect. > % og
I know a Gentleman of a tender frame of Body, who having once, by over reaching, {trained the parts about the Breaft; fell thereupon into a {pitting of Blood, which for a Year and half conftantly retura’d every New Moon, and de- creafing gradually, continued a.ways 4 or 5 days. The Fits being more or lefs confiderable, accord- ing as his management about that time, contri- buted to a greater or leffer fullnefs of the Vef- fels, |
We have two notable Inftances of the like nature in our Philofophical Tranfactions , the one (a) of aPerfon, who from his Infancy to the 24th Year of his Age, had every full Moon an Eruption of Blood on the right fide of the Nail of his left Thumb, at firft to 3 or 4 Ounces, and after his fixteenth Year, to half a Pound each time; which when by fearing the part with a hot Iron, he{topp’d, he fell into a Sputum San- guinis, and by frequent Bleeding, ©c. was very
> \ dificulelye
nae (a) N° 272. : i i
Mifcellanea Curiofa. 387 difficultly faved from a Confumption. The o- ther (b) isa Story of an Inn-Keeper in Ireland, who from the 43 Year of his Life, to the 55th (in which it killed him) fuflered a Periodical E- vacuation at the point of the Fore-Finger of his Right-hand; and altho the Fits here kept not their returns fo certain as in the forementioned Cafe, (it may be either from the irregular way of living of the Patient, or the mighty change eve- ry Effufion made in his habit of Body, the quan. tity feldom amounting to lefs than four Pounds at atime) yet there is this remarkable Circum- {tance in the Relation, that the firft beginning of this Hemorrhage was at Eafter, that is, the next Full Moon after the Vernal Equinox, which is one of the two Seafons of the Year, at which we _ have proved the attraction of the Air, or leffen- ing of its Preffure, to be greater than at any other time whatfoever. :
But we are befides this to confider, That the Sta- tic Chair, and nice Obfervation taught Sanétorius, (b) That Men do increafe a Pound or two in their weight every Month which overplus is difcharged at the Months end, by aCrifis of copioussor thick turbidUrine.
It is not therefore at all ftrange that we fhou’d once a Month be liable to the returns of fuch _ Diftempers as depend upon a Fullnefs of the Veffels, that thefe fhould take place at thofe times efpecially, when the ambient Air is leaft able to reprefs the “Turgency ; and that tho’ New and Full Moon are bath of equal Force, yet that fometimes one, and fometimes the o- ther only fhould Influence the Periods, accord-
4 Cc "ing
(a) Philof, Trauf. N° 171. tah (b) Medicin. Statice, Seg. I, Aph. 650
388 Mi/cellanea. Curiofa.
ing as this or. that happens to. fall: in with the inward Repletion. | Gehl 4 The Afpgux of Humours to Ulcers is fometimes manifeftly altered by. this Power ; (4) Baglivi -was acquainted. with. a. Learned: Young Man at Rome, who. labour’d under a Fiftula in the Abdo- men, penetrating to the Colon, which difcharged fo plentifully in the Increafe, and fo fparingly-in the Decreafe of the Moon, that he could make a very true judgment of the Periods and Quadra- tures of the Planet, from the different quantity of the Matrer that came from Him, | Nepbritic Paroxyfms have frequently been obferved to obey. the Lunar Attraction: Tulpius (b) relates the Café of Mr. Ainfworth, an Eng- lifh: Minifter at Amfterdam, who had a Fit of the Gravel and fupprettion of Urine every Full Moon, of which he found no relief till. the Moon de- creafed, unlefs by Bleeding at the Arm. After his death rwo large Stones were taken out of his — Bladder, and the Pelos of the left Kidney was enlarged to that degree by the quantity of Urine fo often ftopt there, as to contain almoft as much as the Bladder ir felf. a atl I was prefent, not long fince, at the DiffeGtion of a Chid about 5 or 6 Year old, who dyed of the frequent returns of Nephritic Fits, attended with Vomitings and a Diarrhea. - The Kidneys and Ureters were quite {tufted with a flimy calcu: lous Matter, and it was very inftructive to fee the different degrees of Concretion in the feveral parts of it, from a clear limpid. Water,. to a hard friable Subitance. Dr. Groenvelt,.who had agi : e
(a) De Experiment, circa Sanguin.. pe M.340e. (b) Obfervat. Lib. 2+ ¢. 43. vid. etiam Obferv, §2+
Mifcellanea Curiofa. 289 ed the Boy in his Iilnefs, obferved him to be feized with his Pains at every Full Moon for fe- veral Months together, which generally ended with the voiding of a Stone. :
What Influence the Moon has in Afthma’s, (a) van Helmont takes Notice, Exaterbatur Paroxy{mus (fays he) Lune Stationibus, © evi tempeftatibus guas ideo prafentit © prafagit (b) And Sir Fohn Fleyer, who has given us a more particular Hi- {tory of this Difeafe than any Author, oblerves, that The Fits ufually return once in a Fortnights and frequently happen near the Change of the Mcons
°Tis a more uncommon Effe& of this Attra- Etive Power that is related by the Learned Kerck- . ringius. (c) He knew a Young Gentlewoman, whofe Beauty depended upon the Lunar Force, infomuch that at Full Moon fhe was Plump and very Handfome, but in the decreafe of the Planet fo Wan and ill Favoured, that fhe was afham’d to go abroad till the return of the New Moon _ gave Fullnefs to’her Face, and Attra@icn to her Charms. |
Tho’ this is indeed no more than an Influ- , ence of the fame kind, with that the Moon has always been obferved to have upon Sheil-Fith, and fome other living Creatures, For as the old Latin Poet Lucilius fays, (d) ; ;
Luna alit Oftrea &5 implet Echinos, Muribu’ fibras Et Pecui addit ——————- -—__~
Ce. 2 | And (a) Afthma (9 Tuff. § 22. (b) Treatife of the Afthma, p, 17.
(Cc) Obfervat. Anatomic. 92. (d) Apud A. Gellium, lib. 20°¢. 8:
390 Mifcellanea Curiofa. And after him Mansliu (a) .
Sic [ubmerfa fretvs concharum & Carcere claufa, Ad Lune motum variant animalia corpus.
It is very well worth the pains to enquire what fhare fuch an Alteration in the Weight and Pref- fure of the Atmofphere may have in the Crifes or Changes of Acute Difeafés. "The Ancients made great Account of Critical Days, and regulated their Praétice according to the Expe€tation they — had from them ; This Part of Phyfick 1s grown now into difufe, quite flighted, and even ridi- culed; and that I fuppofe chiefly for thefe two reafons. In the firft place, becaufe the earlieft Ob- fervations of this kind, which were drawn into Rules being made in Eaftern Countries, when . thefe came to be applied to the Diftempers of Northern Regions, without allowance given for the difference of the Climate, they were often- times found not to anfwer. And fecondly, ‘Fe- vers of old were treated with few or no Medi- cines, the Motions of Nature were, carefully watched, and no Violence offer’d to interrupt her Work. The Hiftories therefore of Crifes, tho’ of great Ufe, and certainty under fuch Management as this, were at length unavoidably fet afide and loft; when Acute Cafes came to be Cured, ac- cording to this or that Hypothefis, not only by Evacuations, but hot or cold Alteratives too ; there being no longer any room for thofe Laws of Practice which fuppofed a regular and uniform Progrefs of the Diftemper.
meg ‘Where-
(a) Aftronomic. libs 2.
Mifcellanea Curiofa. 391 _. Wherefore, in order to underftand a litle both what might Induce the firft Mafters of our Profeffion to fo nice and {tri&t an Obiervance in this point ; and what grounds there may be now, for a more due regard to their Precepts, even upon the fcore of the Lunar Attraction only, I propoie the following Remarks, |
1. All Epidemic Difeafes do in their regular courfe require a {tated time, in which they come to their height, decline, and leave the Body free,
This is fo conftant and certain, that when a Fever of any Conftitution which is continual in one Subjeét, happens from fome other caufe, in another to be intermitting, the Paroxyims do al- ‘ways return fo often as all together to make up juft as many days of IIInefs as he fuffers, whofe Diftemper goes on from beginning to end, with- out any abatement.
’ Dr. Sydenham, a {worn Enemy to all Theories, Tearn’d thus much from downright Obfervation ; and gives this reafon why Autumnal Quartans hold fix Months, becaufe by computation the Fits of {0 long a time amount to 326 hours, or 14 days, the period of a continual Fever of the fame Seafon. (a) mo
So Galen takes notice that when an Exquifite Tertian "terminated in feven Paroxyfms, a true Continual at the fame time has its Crifis in feven
days; thatis, the Fever lafts as long,in one as in the other, in as much (fays he) as @ Fit in an Intermitting Feaver anfwers to a day in a Continue
al (6). Now this fo comes to pafs, becaufe Cy 2. In
r 2 : eke ree :
(a) De Feber, Intermit. Aun. 1665. pag. Mm, 65. (5) Comment, in Apher, $9. Jide 4. © de Cribs lilte 216+ Ga
392 Mifcellanea Curiofa.
2. In thefe Cafes there is always a Fermenta- tion in the Blood, which gees not off till the
active Particles are thrown out by thofe Organs — of Secretion, which, according to the Laws of
Motion, are moft fitted to feparate em. And 3 As different Liquors put upon a Ferment,
ars cepurated in different times, fo the Arterial
Fluid cakes up a determined Period, of which it is dilcharged of an induced Effervefcence.
4. The Symptoms, during this Fbullition, do not proceed all along in the fame Tenour ; but on fome days particularly, they give fuch evi- dent Marks of their good or bad Quality, that ’ the nature of the enfuing Solution may very well be guefs’d at, and foretold by ’em.
Things being thus, Thofe days on which the Difeale was fo evidently terminated one way or other, might very juftly be call'd the days of Crifis; and chofe upon which the tendency of Ilneis was difcovered by moft vifible Tokens, the Indices of the Critical Days. ’ eG
And thus far the Foundation was good, but when a falfe Theory happen’d unluckily to be joined to true Obfervations, this did a little puz- zle the Caufe. Hippocrates, it is plain, knew not to what to afcribe that remarkable regularity with which he faw the Periods of Fe@¥ers were ended on the Seventh, Fourteenth, One and Twen-~ tieth day, (3c. Pythagoras his Philofophy was in thofe Ages very. Famous, of which Harmony and the Myfferies of Numbers made a confiderable part, Odd were more Powerful than Even, and Seven was the moft perfect of all. Our great Phyficie an efpoufed thefe Notions, (a) and confined the | wee fs Stages
| (2) Epidem. lib, Ie Seat. by
“Se 7
Mifcellanea Curiofa, 393 Stages of acute Diftempers to a Septenary Pro. greffion (4), upon which this Inconvenience fole low’d, that when a Crifis fell out a day fooner or later than this Computation required, his Meafures were quite broken ; and that this muft aoe oftentimes happen, will appear by and by. 3 he d Upon this fcore Afclepiades rejected this whole Doéirine as vain, (4) ‘and Celfis finding it to be too nice and fcrupulous, obferves that the Py- thagorean Numbers led'the Ancients inte the Er= ror. (c) heb? yD ry Galen being aware of this, furcceeded much better in his reafoning upon the Matter, and ve- ry happily imputed the Critical Changes not to thie Power of Numbers, but to the Influence of the Moon ; ‘which he obférves, has a mighty A- &ion upon our Earth, exceeding the other Planets, not in Energy, but in Neéarnefs (d). So that ac- cording to him} the Septenary Periods in Difeafes are owing to the Quarterly Lunar Phafes, which are the times of the greateft Force, and which ree turn in about feven days. (e) _. the ta hes The refult of the whole Affair, in fhort is this, A Cris is no more than the Expulfion of the Morbific Matter out of the Body, thro’ fome or other of the Secretory Organs; in order to which; it is neceflary that this fhould be prepar’d Oca and
wane at ee ee
(a) af aay by iter earionpbraral claw ey robe mRASOIS Gite TeATAL y EBDousalar, T.aAALi wo. Tee ei Wioav, ModAal SE H Toss Euevoss. de Sepsimefirs
artu, ‘ ,
(b) Vid. Celfum lib. 3. c. 4.
(c) 7bid. ' | ae
(A) De diebus Decretor. lib. go
€e) Lbid. )
394 Miaifcellanea Curiofa. and comminuted to fuch a degree, as is requi- red to make it pafs into the Orifices of the refpe- &tive Glands; and therefore a: the moft perfeé Crifis is by Sweat, (both by reafon that the Sub-
cutaneous Glands do naturally difcharge more
than all the other put together, and alfo that
their Duéts being the fmalleft of any, whatfoe-. ver comes this way is certainly wery well divi-
ded and broken) fo the moft imperfett is an Ha- morrhage, becaufe ‘This 1s an Argument that what
Offends is not fit to be caft off in any Part, and
confequently breaks the Veffels by the Efferve- {cence of the Blood: An Abjcefs in thofe Organs
which feparate thick, flimy Juices is of a middle
nature betwixt thefe two. i ~ Nowitisvery plain, That ifthe time, in whic
either the Peccant Humour is prepar’d for Secre- tion, or the Fermentation: of the Blood is come
to its height, falls in with thofe Changes in the -
Atmofphere which diminifh its preffure; the Cri- fis will then be more compleat and large. And alfo, that this Work may be forwarded or de- lay’da day, upon the account of fuch an: Altera- tion in the Air; the Diftention of the Veflels up- on which it depends, being hereby made more eafie, and a weak Habit of Body in fome Cafes {tanding in need of this outward Affiftance. Thus a Fever which requires.about a Week to its Pe- riod, may fometimes, as Hippocrates obferved, have a good Crifis on the fixth, and {ometimes not till the eighth day. i
In Order therefore to make true Obfervations .
of this kind, the time of Invafion is to be confi- dered, The genuine courfe of the Diftemper muft firft be watched, which is not to be. interrupted by any violent Methods: The ftrength of Na-
ture in the Patient. is to be confidered, and by | what -
f
Mifcellanea Curiofa. 395 what Secretions the Crifis is moft likely to be per= formed ; and it will then be found, that not only the New and Full Moons, but-even the Soush- ings, whether vifible or latent, of the Planet, are here of confiderable Moment.
For Confirmation of which, we need only to reflect on what Mr. Pafchal has remark’d, con- cerning the Motions of Difeafes and Births and Deaths (a). Dividing the NuxGiycgor into Four Se- naries of Hours, the firft confifts of three hours before the Southing of the Moon, and three af: ter ; the fecond of the fix hours following, and the third and fourth of the remaining Quarters of the natural day ; He takes notice thar none are born, or die a natural Death in the firft and third Senaries, which calls firft and fecond Tides, but all either inthe fecond or fourth Sena- ries, which he calls firft and fecond Ebbs. In like manner, that in Agues, the tumult of the Fits generally lafts all the Tiding time, and then _ goes off in kindly Sweats in the Ebbs. From whence he very rationally concludes, that Moti- on, Vigour, Action, Strength, &c. appear moft, and do beft in the Tiding Senaries ; and that Reft, Relaxation, Decay, Diffolution, €c, belong to the Ebbing Senaries.
(a) Philof. Tranfak. N° 202.
nite fre re E04 rk O: fot git
ee + Wik ty) ve me
rte ee hit, ig, il he di sade
ave
“\pflghe i tony seins hess sadly bas ont bod eaitos heal
0397)"
A
T having bin explained in the Begin- @ = ning of this Difcourfe;how thofe In- fluences of the Heavens, which fa- vour the Returns of Difeafes, may like- wife raife Winds at the fame times; and that We feel the different Effects of Thefe according as other Caufes do concurr to the Motion of the Air; it will not be amifs, to fhew in one Inftance or two, ~ how much Natural Hiftory confirms this Reafoning. There happened on the 26th of No- _ vember, 1703, a little before Midnight, a moft terrible Storm of Wind, the Fu- ry of it is ftill frefh in every ones Mind, ’ which lafted above fix Hours. It is not to the prefent purpofe to re- date its Hiftory atid Caufes; What we obferve is, That the Moon was at that time in Perigago, and juft upon the change to New. Upon both which ac- counts its Action in raifing the Atmo- {phere muft be great ; And hence indeed the Tides which followed were alfo very | great,
398 = Mifcellanea Curiofa. great, and the Mercury in the Barome- .
a at leaft, in moft places, fell very ow. |
This Influence was, without all doubt,
affifted by fome fuch other Caufes of Winds, as we have mentioned ; Thefe we can’t know, but may however take notice how much the manifeft State of the Air contributed to this Calamity. _ After a greater quantity of Rains than © ordinary had fallen in the Summer and — Autumn, in thofe places where the Storm was felt, the. Winter came on much warmer than ufual ; fo that the Liquor in a Thermometer, of which the 84th Degree notes Froft, never fell below the tooth. (4)
Hence we may very well believe, that the Atmofphere was at that time fill’d with Atoms of Salts and Sulphur, out of the Vapours raifed by the Heat from the moift Earth, which being varioufly combined and agitated, gave that dead- ly force tothe Motion of the Air,
A Proof of this we have not only from the frequent Flafbes of Lightning, obferved a little before the Storm, but alfo from what the Country People took notice of the next day, that the Grafs
- (a) Vid. Philof. Tranfact. N 289.
Mifceilanea Curiofa. 399 and Twiges of the Trees, in Fields re- mote from the Sea, tafted very falt, fo that the Cattle woud not feed on
them. | _ Our Hiftories mention another Storm, which if not equal to this laft in Vio- lence, is however thought the greateft that had then ever been known and me- ‘ morable from the time at which it hap- pened, viz. on the 3d of September, 1658. the day on which the Ufurper O,
Cromwel died. : Hart No Ephemerides that I know of relate the Condition of the Air that Year, but it is fufficient to remark, That whatever other Caufes concurr’d, their force was accompanied with a Full Moon, jutt before the time of the Atumnal Egui- “NIX. - Upon the fame fcore it comes to pafs,. That in thofe Countries which are Sub-._ _je& to frequent Inundations , thefe Calamities are obferved to happen at the times of the Moon's greateft Influ- ence, fo that the Learned Baccius (2) has rightly enough laid the Caufe of fuch Mifchiefs upon immoderate Tides of the Ocean, being unhappily accompanied. | | . with
(a) Del Tevere, lib, 3. p.228._
400 Mifcellanea Guriofa, with the attractive Force of fome or o- ther Stars. for | Dr. Childrey in his Britannia Baconi- ca (a) has from feveral Inftances fhewn the Lunar Adion in Damages of this kind. a eb Such and the like Natural Caufes have Storms and Tempefts: for as to the Queftion of Divine Power, whe- ther or no Calamities of this kind do not fometimes, by the Anger of Hea-. ven, happen out of the Courfe of Na- ture, it is not my Bufinefs to Difpute, nor would I by any means indeavour to abfolve Mens Minds from- the Bands of Religion. For although we muft allow all the Parts of the Ma- chine of this World. to be framed and moved by Eftablifhed Laws, and that the fame Difpofition of its Fabrick, which is moft beneficial to the Whole, muft of neceflity, in fome few Places now and thet occafion Hurts and Mif- chiefs’; it is however moft-highly rea- fonable, that we fhould yield to the Supreme’ Créeator an abfolute Power-- over all his'Works ; Concluding with- al, that it was perhaps agreeable to Di- vine Wifdom, to order the aan us oO
(a) Pag. 97.
Mifcellanea Curiofa. 401 of the World after fuch a manner as might fometimes bring Mifchiefs and Calamities upon Mankind, whom it was neceflary by the Frights of Storms, Thun- der and Lightning to keep in a continual Sence of their Duty. ee
The End.
nine (rm 2a a0 Ht
pee
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