MOTOR FORCE OF THE WORLD MACHINE 257 



new measures of the earth are related. He is stirred up to try 

 anew. He goes back, rummages out his old papers, and begins 

 again. As he foresees that the calculations will verify his surmise, 

 his hand trembles so that he must lay down his pen. Still he 

 does not publish his results. He has had annoying contro- 

 versies with Hooke and others respecting the originality of his 

 invention of the reflecting telescope, his discovery of the com- 

 position of white light. He seems to care little for publicity, 

 and disputes disturb the pursuits of his peaceful life. Thus it 

 is that four or five years later yet, when Halley comes down 

 to inquire as to what will be the path of a body acted on by 

 force of attraction varying inversely as the square of the dis- 

 tance, Newton is able to reply promptly, " An ellipse." How 

 does he know ? " I have proved it." Halley travels back to 

 London big with the news of the great discovery. Newton 

 cannot find his papers just at the moment, but sends them a 

 little later. A little later still, under the reiterate urging of 

 Halley and the others, the Principia is begun. 



Such is the classical tale as you find it in Brewster or the 

 encyclopaedias. The history of perhaps the most far-reaching 

 single discovery in the whole range of scientific development is 

 assuredly worth knowing, and correctly, if that be possible. We 

 may believe with Rosenberger, whose learned and impartial 

 monograph l considers the question at length, that the story of 

 the apple is doubtless a myth ; likewise that the reputed discovery 

 in 1665 was rather one of those ideas which boom into the 

 teeming brain of youth, to be put aside or forgotten as easily 

 as it had come. 



That Newton should be consciously so near the solution of 

 so vast a problem, then give it up because the figures do not 

 quite agree, does not fit with his character. His tenacity was 

 extraordinary. Afterwards, to test out whether or no the law 

 of gravitation was of universal application, he tries with his 

 own hands every kind of substance which he may lay hold of. 

 Even in 1665 the measures of the earth, which are said to have 

 led him astray, were out of date. It is scarcely believable 

 that a man of his original and investigating mind would have 

 been content to accept the erroneous figures without further 

 question, when the error was so slight, and when he, moreover, 

 1 Newton und seine Physikalischen Principien. Leipzig, 1895. 



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