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THE MANHOOD OF NEWTON. Memoir* of the Li...
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Note: This text has been automatically extracted via Optical Character Recognition (OCR) software. The text has not been manually corrected and should not be relied on to be an accurate representation of the item.
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The Manhood Of Newton. Memoir* Of The Li...
THE MANHOOD OF NEWTON . Memoir * of the Life , Writings , and Discoveries of Sir Isaac Newton . By Sir David Brewster . Constable and Co . ( SECOND ARTICLE . ) Ijj- a former article we rapidly ran through the Boyhood of the illustrious ph ilosopher , showing the traces of the truth " The Child is Father to the Man . " With the epoch of Boyhood ceases what may be called the purely biographic interest of these volumes : the man retires into the background , the phtlosopJier usurps the scene . Not that Sir David Brewster has failed in collecting far and wide some biographical details , crushing by the way some popu lar errors , but the biography ceases to be interesting . We are elad to
learn that JNewtons alleged insanity was only a brief illness ; we are not sorry to learn that the old story about his dog Diamond destroying his p apers , but not thereby ruffling his temper , is a pure fiction , Newton never having kept a dog ; we are glad to be put right respecting the composition of his . theological writings , and we follow witb . some eagerness the history of the disputes with Leibnitz and Hatusteed ; but the biography , as a biography , is not interesting ; and although criticism may have much to say to the wide latitude of digression Sir David has allowed himself , it is certain that the most valuable portions of these bulky volumes are those pages which relate to Newton ' s discoveries and the sciences he so magnificently illustrated .
It is worthy of remark that Newton , who , as his mathematical rival , Leibnitz , confessed , had done as much as all the mathematicians who preceded him put together , began his studies by a contempt of Euclid ! He had purchased a book on Judicial Astrology , and finding he could not understand the figure of the heavens without a knowledge of trigonometry , hegot a copy of Euclid with an index of all the problems at the end , and Having turned to two or three which he thought likely to remove his difficulties , he found the truths which they enunciated so self-evident , that he expressed his astonishment that any person should have taken the trouble of writing a demonstration of
them . He , therefore , threw aside Euclid " as a trifling book , " and set himself to the study of Descartes' ( Jeoraetry , where problems not so simple seem to have baffled his ingenuity . Even after reading a few pages , he got beyond his depth , and laid aside the work ; and be is said to have resumed it again and again , alternately retreating and advancing till he was master of the whole , without having received any assistance . The neglect which he had shown of the elementary truths of geometry he afterwards regarded as a mistake in his mathematical studies ; and on a future occasion he expressed to Dr . Peiuberton his regret tliat " he had applied himself to the works of Descartes , and other algebraic writers , before he had considered the Elements of Euclid with that attention which so excellent a writer deserved . "
In four years afterwards he made his discovery of Fluxions ! The first gleam of the discovery of gravitation is thus recorded by Sir David : — It was doubtless in the same remarkable year 1666 , or perhaps in the autumn of 1665 , that Newton ' s mind was first directed to the subject of gravity . He appears to have left Cambridge some time before , the 8 th of August , 1665 , when the College was " dismissed" on account of the Plague , and it was , therefore , in the autumn of that year , and not in that of 1666 , that the apple is said to have fallen from the tree at Woolsthorpe , and suggested to Newton the idea of gravity . When sitting alone in the garden , and speculating on the power of gravity , it occurred to him that as the same power by which the apple fell to the ground was not sensibly diminished at the greatest distance from the centre of the earth to which we can reach , neither at the summits of the loftiest spires , nor on the tops of the highest mountains , it might extend to the moon and retain her in her orbit , in the same manner as it bends into a curve a stone or a cannon-ball , when projected in a straight line from the surface of the earth . If the moon was thus kept in her orbit by gravitation to the earth , or , in
other words , its attraction , it was equally probable , he thought , that the planets were kept in their orbits by gravitating towards the sun . Kepler had discovered the great law of the planetary motions , that the squares of their periodic times were as the cubes of their distances from the sun , and henco Newton drew the important conclusion that the force of gravity or attraction , by which the planets -were retained in their orbits , varied as the square of their distances from the sun . Knowing the force of gravity at the earth ' s surface , he was , therefore , led to compare it with the force exhibited in the nctunl motion of the moon , in a circular orbit ; but having assumed that the distance of the moon from the earth was equal to sixty of the earth ' s semidiametcra , he found that the force by which the moon was drawn from its rectilineal path in a second Of time was only 13-9 feet , whereas at the surface of the earth it was 16 * 1 In a second . This great diacrepnncy between his theory and what he then considered to be the fact , induced him to abandon the subject , and pursue other studies with which he had been previously occupied . Yet tiiis positive thinker , whose name is indelibly associated with the exact sciences , paid his tribute to the age , and believed in Alchemy : —
In hla chemical studies , which , a « we have just seen , he hud recently commenced , his mind was impressed with hoiuo belief in the doctrines of alchemy , and he certainly pursued his experiments to a late jxjriod of bis life , with the hope of eflecting some valuable transmutation : * . Among the subjects , therefore , to which he requests Mr . AehtOn to pay attention , there arc . « evernl which indiente this tendency of his mind . Htfdetires him to observe the products of nature , especially in mines , with the circmtistances of mining , and of extracting metals or minerals out of their ores , and refining them ; and , what lie considered as far more important than this , lie wishes him to observe if there wore any transmutations out of one Bpecies into another , as , fQr example , out of iron into copper , out of one salt into another , or into an insipid H 4 y , & c . Such transmutation * , U « adds , arc above all others worth his noting , being thaptost luctfcrou * , and many ( vms lucriftrous fj-jMTimmts too , in philosophy ! Among the particular observations to which ho calls the attention of his friend , is that of a certain vitriolwhich changes iron into copper , and which is said to be kept a secret
, foe the lucrative mimoMi of irfloidiiir that transmutation . He is to inquire also whefor { ho lucrative pnrpOhO of cft'ccling that transmutation . He is to inquire also whefterin Hungary , or in the mountain * of Bohemia , th . ro are rivers whose waters arc Impregnated with cold , dinHolvcd by some corrosive Hindu like aqua regis ; and whetlftV tho practice of laying mercury in tho rivers till it bo tinged with gold , and then Wptratlng tho gold by straining tho mercury through leather , bo still a secret or openl y practised . There was at this time in Holland a notorious alchemist of tho naijia ofrBory , who , n « Sir Isaac says , was homo years since imprisoned by tho Pope , In order to extort from him secrets of great worth , both " ah to inccUclno and prolit , *«> 4 "Who made hia e » capo into Holland , where they grunted htm a guard . " I think , a % Slr Isaac , u lib uuunlly goea clothed in green : pray , inquire what you can of M jfy and whether his ingenuity bo any prolit to tho Dutch !" Hji great discovery of tho rofrangibility of light is well told by Sir David , Whft not only shows tho cautious experimental method by winch tho
discovery was established , but also calls attention to the rare fact of this ' dig . covery being one which has never been claimed for any previous philosopher . JSo one had a suspicion , not even a plausible conjecture to offer on . the nature and origin of colours . Newton ' s discovery was a leap from abso-Lv ^ 'E ^ Tft ? demonstration ; no one had prepared the way " no one had even hinted that there might be a way . No sooner were his optical discoveries announced , than they were assailed with the virulence wh & h usually welcomes discovery in science ; and it is interesting and instructive to note that Newton himself refused to acknowledge the beautiful law of double reex ^ rimeStafysis ? ^ 7 * ^^ * ^ funded on the finest Sir David justly criticises the current idea of Newton having exhibited extraordinary sagacity m his conjecture about the diamond —
The conjecture of Newton that the diamond " is an unctuous substance coagulated . " has been generally regarded as a proof of singular sagacity , and as aa anticipationof the results of chemical analysis ; but it is certainly not entitled to such praise . Its solitary position among the oils and inflammable bodies led to the conjecture - but had he known the refractive index and specific gravities of greenoctete and octokedrite , he would have drawn the same conclusion respecting them , and been mistaken . The real inference respecting the composition of the diamond , which Newton ' s Table authorises , is not that it should consist of carbon , but of sulphur . " So then , " says he , "by the foregoing table , all bodies seem to have their refractive powers proportional to their densities ( or very nearly ) excepting so far as they partake more or less of sulphureous oily particles , and thereby have their refractive power made greater or less . Whence it seems rational to attribute the refractive power of all bodies chiefly , if not wholly , to the sulphureous particles with which they abound . For it is probable that all bodies abound more or less with sulphurs . And as light congregated by a burning glass acts most upon sulphureous bodies , to turn them into fire and flame , so , since all action is mutual , sulphurs ought to act most upon light . "
Those who are interested in the history of Science will read with peculiar interest the celebrated Letter to Boyle , in which Newton gives a sketch of his hypothesis of a universal ether . Here is a man who in Astronomy and Physics proceeds with the utmost caution , moving only by the guidance of experiment and clear fact , and no sooner does he approach the more complex science of Biology than he gives the rein to supposition with the wildness of a Galen or an Averrhoes . The " puzzling problem by what means the muscles are contracted and dilated to cause animal motion , " may , he thinks , have more light thrown on it by his hypothesis than by any . other ; and this is the explanation : —
First , then , I suppose there is such a spirit ; that is , that the animal spirits are neither like the liquor , vapour , or gas of spirits of wine ; but of an setherial nature , subtile enough to pervade the animal juices as freely as the electric , or perhaps magnetic , effluvia do glass . And to know how the coats of the brain , nerves , and muscles may become a convenient vessel to hold so subtile a spirit , you may consider how liquors and spirits are disposed to pervade , or not pervade , things on other accounts than , their subtilty ; water and oil pervade wood and stone , which quicksilver does not ; and quicksilver , metals , which water and oil do not ; water and acid spirits pervade salts , which oil and spirit of wine do not ; and oil and spirit of wine pervade sulphur , which water and acid spirits do not ; so some fluids ( as oil and water ) , though their parts are" in freedom enough to mix with one another , yet by some secret principle of unsociableness they keep asunder ; and some that are sociable may become unsociable by adding a third thing to one of them , as water to spirit of wine by dissolving
salt of tartar in it- The like tmsociableness may be in setherial natures , as perhaps between the aethers in the voTtices of the sun and planets ; and the reason why air stands rarer in the bores of small glass pipes , and aether in the pores of bodies , may be , not -want of subtilty , but sociableness ; and on this ground , if the astberial vital spirit in a man be very sociable to the marrow and juices , and unsociable to the coats of the brain , nerves , and muscles , or to anything lodged in the pores of those coats , it may be contained thereby , notwithstanding its subtilty ; especially if we suppose no great violence done to it to squeeze it out , and that it may not be altogether so subtile as the main body of a ? ther , though subtile enough to pervade readily the animal juices , and that as any of it is spent , it is continually supplied by new spirit from the heart . In the next place , for knowing how this spirit may be used for animal motion , you may consider how some things unsociable are made sociable by the mediation of a third . Water , which will not dissolve copper , will do it if the copper be melted with sulphur . Aquafortis , which will not pervade gold , will do it by addition of a
little sal-ammoniac or spirit of salt . Lead will not mix : in melting with copper ; but if a little tin , or antimony , be added , they mix readily , and part again of their own accord , if the antimony be wasted by throwing saltpetre , or otherwise . And so lead melted with silver quickly pervades and liquefies the silver in a much less heat than la required to melt the silver alone ; but if they be kept in the test till that little substance that reconciled them be wasted or altered , they part again of their own accord . And in like manner the aitherial animal spirit in a man may be a mediator between the common asther and the muscular juices , to make them mix more freely ; and so by sending a little of tiiis spirit into any muscle , though so little as to cause no sensible tension of the muscle by its own force , yet by rendering tho juices more sociable to the common external nether , it may cause that rether to pervade the muscle of its own accord in a moment more freely and more copiously than it would otherwise do , and to recede again as freely , saloon as this mediator of sociablenesa ia retracted ; whence , according to what I said above , will proceed the swelling or shrinking of the muscleand consequently the animal motion depending thereon .
, Thus may thercforo the soul , by determining this letherial animal spirit or wind into this or that nerve , perhaps with as much ease as air is moved , in open spaces , cause nil the motions wo sec in animals ; for the making which motions strong , it ia not necessary that we should suppose tho wther within the musclo very much condensed , or rarefied , by this means , but only that its spring is so very great that a little ulterntion of its density ahull cause a great alteration in the pressure . And what is said of muscular motion may be applied to the motion of the heart , only with this difference , that tho spirit is not sent thither as into other muscles , but continually generated thero by the fermentation of the juices with which its flesh is replenished , and as it ia generated , lot out by starts into the brain , through some convenient dttctu * , to perform those motions in other muscles by inspiration , which it did in tho n < 3 * r 5 "Y its generation . For I seo not why tho ferment in the heart may not raise as auhtue a spirit out of its juices , to cause those motions , as rubbing docs out of a glass to causu electric attraction , or burning out of fuel to penotrato glass , as Mr . Boyle naa snown .
and calcine by corrosion motala melted therein . It is well that from time to time wo should bo able thus to 8 ^ . ™ ™* speculated ; from tho errors of the past we may learn wmot ^ nj , uset ui to the present ; from tho errors of a fcowton we . nay ear ., > to ^ f ^ SS caation tho opinions of those to whom wo hstcn with the greatest lespoct .
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Citation
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Leader (1850-1860), July 28, 1855, page 17, in the Nineteenth-Century Serials Edition (2008; 2018) ncse2.kdl.kcl.ac.uk/periodicals/l/issues/cld_28071855/page/17/
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