9S 



TEE POPULAR SCIENCE MONTELY.— SUPPLEMENT 



principles on the otherwise bewildering flux of 

 phenomena. He has been described by the Ger- 

 man Licktenberg as " das rastlose Ursachenthicr " 

 — the restless, cause -seeking animal, in whom 

 facts excite a kind of hunger to know the sources 

 from which they spring. Never, I venture to say, 

 in the history of the world, has this longing been 

 more liberally responded to, both among men of 

 science and the general public, than during the last 

 thirty or forty years. I say " the general public," 

 because it is a feature of our time that the man 

 of science no longer limits his labors to the so- 

 ciety of his colleagues and his peers, but shares, 

 as far as it is possible to share, with the world 

 at large the fruits of inquiry. 



The celebrated Robert Boyle regarded the uni- 

 verse as a machine ; Mr. Carlyle prefers regarding 

 it as a tree. He loves the image of the umbrageous 

 Igdrasil better than that of the Strasburg clock. 

 A machine may be defined as an organism with life 

 and direction outside ; a tree may be defined as 

 an organism with life and direction within. In 

 the light of these definitions, I close with the 

 conception of Carlyle. The order and energy of 

 the universe I hold to be inherent, and not im- 

 posed from without — the expression of fixed law 

 and not of arbitrary will, exercised by what Car- 

 lyle would call an almighty clock-maker. But the 

 two conceptions are not so much opposed to each 

 other, after all. In one fundamental particular 

 they, at all events, agree. They equally imply the 

 interdependence and harmonious interaction of 

 parts, and the subordination of the individual 

 powers of the universal organism to the working 

 of the whole. 



Never were the harmony and interdependence 

 just referred to so clearly recognized as now. 

 Our insight regarding them is not that vague 

 and general insight to which our fathers had 

 attained, and which, in early times, was more 

 frequently affirmed by the synthetic poet than 

 by the scientific man. The interdependence 

 of our day has become quantitative — expres- 

 sible by numbers — leading, it must be added, 

 directly into that inexorable reign of law which 

 so many gentle people regard with dread. In the 

 domain now under review, men of science had 

 first to work their way from darkness into twi- 

 light, and from twilight into day. There is no 

 solution of continuity in science. It is not given 

 to any man, however endowed, to rise spontane- 

 ously into intellectual splendor without the par- 

 entage of antecedent thought. Great discoveries 

 grow. Here, as in other cases, we have first the 

 •seed, then the ear, then the full corn in the ear, 



the last member of the series implying the first. 

 Thus, as regards the discovery of gravitation, 

 with which the name of Newton is identified, no- 

 tions more or less clear concerning it had entered 

 many minds before Newton's transcendent mathe- 

 matical genius raised it to the level of a demon- 

 stration. 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 distribu- 

 tion 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 definite expression. 

 The doom of a doctrine is often practically 

 sealed, and the truth of one is often practically 

 accepted, long prior to the theoretic demon- 

 stration of either the error or the truth. Per- 

 petual motion, for example, was discarded before 

 it was proved to be in opposition to natural law ; 

 and, as regards the connection and interaction of 

 natural forces, prenatal intimations of modern 

 discoveries and results are strewed through scien- 

 tific literature. 



Confining ourselves to recent times, Dr. Ingleby 

 has pointed out to me some singularly sagacious 

 remarks bearing upon this question, which were 

 published by an anonymous writer in 1820. Ro- 

 get's penetration was conspicuous in 1829. Mohr 

 had grasped, in 1S37, 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 com- 

 mon, 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 di- 

 rectly 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-electricity, 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. Colding, though starting from a 

 metaphysical basis, grasped eventually the re- 

 lation 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 in his dealings with 

 scientific history keeps his soul unwarped by 

 envy, hatred, or malice, personal or national, every 

 fresh accession to historic knowledge must be 

 welcome. For every new-comer of proved merit, 



