SCIENCE AND MAN. 599 



Newton's transcendent mathematical genius raised it to 

 the level of a demonstration. The whole of his deductions, 

 moreover, rested upon the inductions of Kepler. Newton 

 shot beyond his predecessors; but his thoughts were rooted 

 in their thoughts, and a just distribution of merit would 

 assign to them a fair portion of the honor of discovery. 



Scientific theories sometimes float like rumors in the 

 air before they receive complete expression. The doom 

 of a doctrine is often practically sealed, and the truth of 

 one is often practically accepted, long prior to the demon- 

 stration of either the error or the truth. Perpetual motion 

 was discarded before it was proved to be opposed to natural 

 law; and, as regards the connection and interaction of 

 natural forces, intimations of modern discoveries are strewn 

 through the writings of Leibnitz, Boyle, Hooke, Locke 

 and others. 



Confining ourselves to recent times. Dr. Ingleby has 

 pointed out to me some singularly sagacious remarks bear- 

 ing upon this question, which were published by an 

 anonymous writer in 1820. Koget's penetration was con- 

 spicuous in 1829. Mohr had grasped in 1837 some deep- 

 lying truth. The writings of Faraday furnish frequent 

 illustrations of his profound belief in the unity of nature. 

 " I have long/' he writes in 1845, " held an opinion almost 

 amounting to conviction, in common, I believe, with other 

 lovers of natural knowledge, that the various forms under 

 which the forces of matter are made manifest have one 

 common origin, or, in other words, are so directly related 

 and mutually dependent, that they are convertible, as it 

 were, one into another, and possess equivalence of power 

 in their action." His own researches on magneto-elec- 

 tricity, on electro-chemistry, and on the "magnetization 

 of light," led him directly to this belief. At an early date 

 Mr. Justice Grove made his mark upon this question. 

 Oolding, though starting from a metaphysical basis, grasped 

 eventually the relation between heat and mechanical 

 work, and sought to determine it experimentally. And 

 here let me say, that to him who has only the truth at 

 heart, and who injhis dealings with scientific history keeps 

 his soul un warped by envy, hatred, or malice, personal or 

 national, every fresh accession to historic knowledge must 

 be welcome. For every newcomer of proved merit, more 

 especially if that merit should have been previously over- 



