290 SIB ISAAC NEWTON. 



crystallized carbon ; and the foundations of mechanical 

 chemistry were laid by him with the boldest induction and 

 most felicitous anticipations of what has since been effected.* 

 The solution of the inverse problem of disturbing forces has 

 led Le Verrier and Adams to the discovery of a new planet, 

 merely by deductions from the manner in which the motions 

 of an old one are affected, and its orbit has been so calculated 

 that observers could find it nay its disc as measured by them 

 only varies one twelve-hundredth part of a degree from the 

 amount given by the theory. Moreover, when Newton gave 

 his estimate of the earth's density, he wrote a century before 

 Maskelyne, by measuring the force of gravitation in the Scotch 

 mountains, 1772, gave the proportion to water as 4-716 to 1 

 and many years after by experiment with mechanical apparatus 

 Cavendish, 1798, corrected this to 5'48, and Baily more re- 

 cently, 1842, to 5'66, Newton having given the proportion as 

 between 5 and 6 times. In these instances he only showed 

 the way and anticipated the result of future inquiry by his 

 followers. But the oblate figure of the earth affords an 

 example of the same kind, with this difference that here he 

 has himself perfected the discovery, and nearly completed the 

 demonstration. From the mutual gravitation of the particles 

 which form its mass, combined with its motion round its axis, 

 he deduced the proposition that it must be flattened at the 

 poles ; and he calculated the proportion of. its polar to its 

 equatorial diameter. By a most refined process he gave this 



* ' Optics,' Book II. prop. 10. It might not be wholly without ground 

 if we conceived him also to have concluded, on optical grounds, that \vuter 

 has some relation to inflammable substances ; for he plainly says that it 

 lias a middle nature between unctuous substances and others ; and this he 

 deduces from its refractive powers, though he gives other reasons in con- 

 firmation. In the celebrated 31st Query, Book III. (p. 355), he plainly 

 considers rusting, inflammation, and respiration, as all occasioned by the 

 acid vapours in which he says the atmosphere abounds. In another place 

 he treats of electricity as existing independent of its production or evolu- 

 tion by friction. Black always spoke of that Query with wonder, for the 

 variety of original views which it presents on almost every branch of 

 chemical science. 



