480 



NEWTON 



He accordingly abandoned the hypothesis for other 

 Mudics. ThcMS otlii-r pursuits "to which In- thus 

 U-took himself consisted chiclly of investigations 

 into tin- imtuie of light, ami tin- MMtnMthH of 

 trlex-opes. Hy a VHricty of ingenious :iml inter- 

 esting ex|ieri ..... ntH upon sunlit-lit refracted through 

 a prism in a darkened apartment, In- was led to tin- 

 conclusion that ru\s>of light which differ in colour 

 differ al> in rafrangibUUy. This discovery enabled 

 him to explain tin ini|ierfii-tion of tin- telescojie, 

 which had not till then Ut-n accounted for. The 

 indistinctness of the linage formed l>y the object- 

 gUs! wan not necessarily due to any imperfection 

 of its form, hut to the fact of th<> diMMn coloured 

 rays of light In-itu; brought to a focus at different 

 distances. He concluded rightly thut it was iniiios- 

 sil.le for an object-glass eonaisttBgaf a single mat 

 t<> produce a distinct image. He went further, and 

 too ha-tily concluding, from a single ex|>eriineiit, 

 that the dispersive power of different sulistances 

 was proportional to their refractive ]>owcr, he pro- 

 nounced it ini|Nissible to produce a perfect intake 

 liy a coniliiimiion of lensi-s. This conclusion since 

 proved erroneous liy thr discovery of the achromatic 

 teh -scope (nee Am it"\i ATISM ) turned Newton's 

 attention to the construction of reflecting tele- 

 scopes ; and the form devised liy him is the one 

 which, at later periods, reached such perfection ill 

 the (minis of Sir \Villiam Herschel and Lord Uosse. 



Newton Waine u Fellow of Trinity in 1067, 

 and Lucasiau professor of Mathematics in 1669; 

 and it was on llth January 1671 that he was 

 elected a memlicr of the lioyal Society, having 

 become known to that liody from his reflecting 

 telescopes. At what period he resumed his cal- 

 culations alxmt gravitation, employing the more 

 correct measure of the earth obtained by Pieard 

 in 1670, does not clearly appear ; but it was in 

 the year Hist that it l>ecame known to Hal ley 

 that he was in possession of the whole theory ami 

 ite demonstration. It was on the urgent solicita- 

 tion of llalley that he was induced to commit to 

 a systematic treatise these principles and their 

 demonstrations. The principal results of his dis- 

 riiveiii-s were set down in a treatise called De Motu 

 Corgioruin, and were afterwards more completely 

 unfolded in the great work entitled J'/ii/xn/Jiin- 

 Suliiriilis I'rinrljtin Miitlifimitirii, which was finally 

 published alMiut inidsummer 1687. 



Shortly lefore the 1'rinriniu. was given to the 

 public Newton had lieen called to take an active 

 part in defending the rights of the university 

 against the illegal encroachments of James II. 

 Tin- conspicuous purl which he had taken on that 

 occasion procured him a sc.u in the Convention 

 Parliament, in which he flit from January Kix'.l to 

 its di-s,,|,,ti, m in HHH). In IlilM} he was appointed 

 Warden of the Mint, and was afterwards promoted 

 to the ollicc of Master of the Mint in HMH), an office 

 which lie held till the end of his life. He again 

 took a scat in parliament in the year 1701 as the 

 representative of his university. Thus engaged in 

 the public service, | l( > had little time left for mere 

 MI ilii- studies pursuits which be always held of 

 secondary im]K>rtance to the public duties in which 

 he was en^a^'ed. In the interval of public duty, 

 however, Newton showed that he still retained the 

 scientific power by which his great discoveries had 

 made. This was shown in his solution of two 



celebrated problems proposed in June lllllli by .lolin 

 <Miilli, as a challenge to the mathematicians of 

 Kurope. A similar niatlicmatical feat is recorded 



of him no late as 1710. in solving a problem pro 

 nosed by l^-ibnit/ for tin- purpose, MM expressed 

 it. of feeling the pulse of the English analysts. 



When in parliament Newtxm recommended the 

 public encouragement of the invention of a method 

 fur determining the longitude the first reward in 



<iucncc lieing gained by John Harrison for big 

 chronometer. He was president of the Itoyal 

 Society from 1703 till his death, a period of 

 twenty-live years, lieing each year re elected. In 

 this push ion he could do much for the advance 

 ment of science: ami one of his most important 

 works during this time was the Mipcrintcnd- 

 ence of the publication of Flamsteed'l Hn-fi, ir,,-/, 

 Obtervation* a task, however, not accomplished 

 without much controversy and some bitterness 

 between himself and that astronomer. The con- 

 troversy lictweeti Newton and Leibnitz ns to 

 priority of discovery of the differential calculus, or 

 the method of fluxions. W:LS raised rather through 

 the partisanship of jealous friends than through 

 the anxiety of tin- philosophers themselves, who 

 were, however, induced to enter into and carry on 

 the dispute with some decree of bitterness ami 

 mutual recrimination. The verdict of the impartial 

 historian of science 11111-1 l>e that the methods 

 were invented quite inde|ieiidently, and that, 

 although Newton was the first inventor, a great ei 

 debt is owing by later analysts to Leibnitz, on 

 account of the superior facility and completeness c,f 

 his method. In Iti'.Kt Newton was elected a forei-n 

 associate of the Academy of Sciences, and in IT 11 :! 

 he received the honour of knighthood from (,'necn 

 Anne. He died at Kensington on 20th March 

 1727, and his remains received a resting place in 

 \\Ysl minster Abbey, where a monument was elected 

 to his memory in 1731. Houbilliac's magnificent 

 full-length statue was erected in 17.">o in the ante- 

 chai>el of Trinity College, Cambridge. 



Besides the first edition of the I'rineipia, other editions 

 appeared in 1713, 17-Vi. 17L".i, 17:!0; and at (.;< neva the 

 Jesuits' edition ( 1":*'.'-4J ; it'pulilinl cd at (IlaKOW, 1M.".' I. 

 An admirable reprint is that liy Ix*rd Kelvin and 

 Professor lilackburn (GUiigow, 1S71 '. Clarke's I.-itn. 

 translation of tlie Oi-tict ppen-d in 1700; the /.licn/ 

 ].tiira in 17^8; the Fluxiont in 1730; and Horsley 

 edited an edition of his oollvcted works (5 Tola. )!<> 

 l"7'.i-H5). Newtun was a student <>f Alchemy (i|.v.i; 

 and he left a remarkable menim ci>t nf his interest in 

 tlieolojO', especially iin)|>lu'cy, MS. work on the pro- 

 phecies of Daniel and on the Apoe.lypse, a history of the 

 Creation, and a number of tracts. See the articles in 

 this work on ASTHONOMY. Fi.rxioxs, CKAVITAIIOX. 

 LIGHT, MOTION (LAWS OK), OITICS, SI-ECTIM-M ; Sir 

 David Brtwster"s Lift of Knrlan (1S55); and Augustus 

 de Morgan's Morton, hit Frinul, and hit A; 

 that friend being John Conduitt ( 1C88-1737 1, Newton's 

 successor as muster of the mint, who in 1717 married 

 N. 'teii 's in. ci . Katlierine Barton, the widuw probably of 

 the Karl of Halifax. 



NrwTux's KINOS. Tn bis investigations of the 

 colours produced by thin plates of any material, 

 solid, fluid, or gaseous. Sir Isaac Newton hit upon 

 the following mode of exhibiting the colours pro- 

 duccil by icllection from a film of air. He took 

 two lenses, one con\ exo plane, its convex side 

 ha\ing a radius of 14 fi'et, the other e|iii convex, 

 with the nulii of its surfaces 50 feet, and laid the 

 lirst with its plane surfiice downwards on the toj 

 of the second, thus producing a thin film of air 

 between the lenses; the film being thinnest near 

 the centre, and becoming gradually thicker out- 

 wards, (tn slowly pie-sin^' the upper lens against 

 the under one, a number of concentric coloured 

 rings, having the point of contact of the lenses tor 

 their centre, appeared, ami increased in si/e when 

 the pressure was increased. These rin^s, or moie 

 properly systems of ring's, are in this form of the 

 experiment seven in number, and each of them is 

 composed of a number (ranging from ciejit in the 



first or smallest riii^' to two in tl utermost i of 



ring's of different colours, the colours, though 

 different in each of the systems of rings, preserv- 

 ing the same arrangement as the colours of the 

 spectrum ; thus, in the second ring the inside 



