IX 



SIR ISAAC NEWTON 



I 642-1 727 



Sir Isaac Newton, whose researches in light, gravitation, and math- 

 ematics are outstanding in the history of modern science, zms born 

 in Woolsthorpe, Lincolnshire, December 2^, 1642. He was the son 

 of an English farmer who died before Newton was born. His early 

 education was interrupted by his mother's poverty, but his ingcnuitv 

 in making mechanical toys soon provided a means whereby he zvas 

 enabled to return to school. He entered Cambridge University in 

 1661 and took his degree in 166^; two years later he zvas made a fel- . 

 low of the university, and in i66p became professor of mathematics. 



In 1665 ^^^ discovered his method of fluxions, not greatly unlike 

 Leibnitz's Differential Calculus. In i6y2 he was elected a fellow 

 of the Royal Society and shortly afterwards sent them a paper de- 

 scribing how he had broken up light by means of a prism, demon- 

 strating by that means the compound fiature of the sun's rays. 



In 168/ he elaborated his theory of gravitation in '^Philosophice 

 Naturalis Principia Mathematica." This was the result of his reflec- 

 tions and researches dating from 1666, zvhen he attempted to explain 

 the moon's motion by the hypothesis of the assumed influence of grav- 

 itation. In the meantime, through the use of telescopic instruments, 

 French geographers had tested the spherical shape of the earth and 

 had made a new and more accurate triangulation. Using the data 

 which they supplied, Newton perceived that these data agreed with 

 his theory that the force varied inversely as the square of the dis- 

 tance. Overcome with the emotion incident to the solution of a 

 great problem, he begged a friend to complete his calculations, with 

 the result that the new astronomy begun by Copernicus, and con- 

 tinued by Brake, Kepler, and Galileo, was formulated and nmthe- 

 matically interpreted by a single mechanical principle. 



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