i92, 193] J\?;i'/Wj Later Life 241 



preparations for a new edition of the Prindpia, besides 

 going on with the lunar theory, but the work was again 

 interrupted in 1695, when he received the valuable appoint- 

 ment of Warden to the Mint, from which he was promoted 

 to the Mastership four years later. He had, in conse- 

 quence, to move to London (1696), and much of his time 

 was henceforward occupied by official duties. In 1701 

 he resigned his professorship at Cambridge, and in the 

 same year was for the second time elected the Parliamentary 

 representative of the University. In 1703 he was chosen 

 President of the Royal Society, an office which he held till 

 his death, and in 1705 he was knighted on the occasion of 

 a royal visit to Cambridge. 



During this time he published (1704) his treatise on 

 Optics , the bulk of which was probably written long before, 

 and in 1709 he finally abandoned the idea of editing the 

 Principia himself, and arranged for the work to be done by 

 Roger Cotes (1682-1716), the brilliant young mathematician 

 whose untimely death a few years later called from Newton 

 the famous eulogy, " If Mr. Cotes had lived we might 

 have known something." The alterations to be made were 

 discussed in a long and active correspondence between the 

 editor and author, the most important changes being 

 improvements and additions to the lunar theory, and to 

 the discussions of precession and of comets, though there 

 were also a very large number of minor changes ; and the 

 new edition appeared in 1713. A third edition, edited by 

 Pemberton, was published in 1726, but this time Newton, 

 who was over 80, took much less part, and the alterations 

 were of no great importance. This was Newton's last piece 

 of scientific work, and his death occurred in the following 

 year (March 3rd, 1727). 



193. It is impossible to give an adequate idea of the 

 immense magnitude of Newton's scientific discoveries 

 except by a free use of the mathematical technicalities in 

 which the bulk of them were expressed. The criticism 

 passed on him by his personal enemy Leibniz that, 

 "Taking mathematics from the beginning of the world 

 to the time when Newton lived, what he had done was 

 much the better half," and the remark of his great suc- 

 cessor Lagrange (chapter XL, 237), "Newton was the 



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