August 1, 1887.] 



♦ KNO"WLKDGE ♦ 



219 



whether terrestrial gravity might not be an example of a 

 property possessed by matter itself; whether the earth's 

 attractive power might not extend to the moon, and be 

 shaved by the sun in such greater degi'ee as corresponded 

 with the sun's greater mass. 



"While the suggestion of these thoughts was independent 

 altogether of any such gathering of evidence as the Baconian 

 method required, the testing of the theory thus suggested 

 was a work of pure deduction. Observations were employed, 

 indeed ; but they were such observations as the theory itself 

 suggested. And the way in which the selection of observa- 

 tions for this special purpose was determined was not only 

 deductive, but depended on such deductions as only a man 

 of Newton's power could have formed. 



Newtonascertained, first by means of mathematical methods 

 of his own devising, that if a force or attraction residing in 

 the sun determines the movements of the planets according 

 to the laws ascertained by Kepler, that force must vary 

 according to the law of tlie inverse squares — that is to say, 

 the force diminishes as the square of the distance increases. 

 He calculated what the earth's known atti'active power, 

 diminishing according to this law, would be at the moon's 

 distance ; and he found (after a long delay, due to the 

 inexact observations and measurements of others) that 

 under an attractive force, so diminishing with distance, the 

 moon would travel around the earth as she actually does. 



But Newton went much further than this. He made 

 experiments and observations to see if tliis attractive force 

 resides in all matter, and is always proportional to the mass 

 or quantity of matter. He then discussed the details of the 

 moon's movements — peculiarities which had long perplexed 

 astronomers, liad long afforded them the means, if Bacon 

 was right, of educing the true theory of her movements, and 

 had all the time taught nothing. 



It was not the consideration ofthe.se peculiarities, not the 

 induction of these observed facts, which led Newton to the 

 true theory. On the contrary, the true theory was deduced 

 from considerations applied to laws already discovered 

 deductively by others ; and the true theory led Newton to 

 consider observed facts and peculiarities. 



Newton went further, however, even than this. By pure 

 deduction from his theory he showed that the moon's move- 

 ments around the earth ought to be affected by certain 

 minor peculiarities caused by the sun's perturbing action, 

 and be invited Flamsteed to ascertain if sucli peculiarities 

 really exist. 



Flamsteed, thus guided, was able to supply the required 

 evidence. As Professor De Morgan well remarked of the 

 achievement, " Had it not been for Newton, the whole 

 dynasty of Greenwich astronomers, from Flamsteed to Airy, 

 might have worked away at nightly observation and daily 

 reduction without any remarkable result, looking forward, 

 as to a millennium, to the time when any man of moderate 

 intelligence was to see the whole explanation " — a time 

 which would never have come, whatever a believer in the 

 Baconian method may imagine. 



There is no evidence that Newton ever paid attention to 

 aught contained either in Bacon's " Advancement of Learn- 

 ing," or in the " Novum Organum." But Newton's work 

 suffices to make it absolutely certain that if he ever did 

 weigh Bacon's method he found it wanting, for he followed 

 a course of the very kind which Bacon had condemned, and 

 carefully avoided the course Bacon had recommended. 

 Moreover, as I wrote in 1865, Newton's success afforded a 

 marked and early illustration of Bacon's error in supposing 

 his system of philosophy would raise all its followers to one 

 level, however variou.s might be their talents and capacities. 

 For of Newton it may justly be said that in genius, as in the 

 work he accomplished, yenus humanum superavit. 



THE STORY OF CREATION. 



a plain account of evolution. 

 By Edward Clodd. 



PART n. 

 CHAPTER YI.—(,Cond,tded.) 



3HAT many and serious objections may be 

 advanced against the theorj' of descent 

 with modification through variation and 

 natural selection, I do not deny. I have 

 endeavoured to give them their full 

 force." * The sixth, seventh, and tenth 

 chapters of the " Oiigin of Species " are 

 proof of this. Darwin shirked no difficulty, and in laying 

 stress upon whatever told against his theory he made its 

 foundations more sure. One great, but unduly over- 

 rated, stumbling-block — the absence of intermediate forms 

 in the fossil-yielding rocks — has been removed by the dis- 

 covery of many more connecting links in the long chain of 

 life than could be expected when we take into account the 

 small minority of fossils which have escaped the havoc of 

 the past, and when we remember how much smaller are the 

 chances in favour of the preservation of the more fragile, 

 rare, and unstable transitional forms than of the species 

 which they connect. 



Another leading objection, drawn from the barrenness of 

 hybrids,t as, e.g. of the mule, loses much of its force in view 

 of the numerous examples to the contrary, both in plants 

 and animals, as amongst genera of the thistle and of the 

 laburnum, and as in the cases of fruitful hybrids of sheep 

 and goats in Chili, and of hares and rabbits in France.^ 

 But, as against natural selection, the real difficulty lies in 

 the inter-breecUng of species developed by selective breeding 

 from a common stock. For example, the different species of 

 pigeons have been developed from the wild rock-pigeon, 

 and these are fertile with one another, which would seem to 

 tell in favour of the fixity of species, unless the carrier, 

 pouter, and tumbler are, after all, to be regarded only as 

 varieties or subdivisions of species § The matter, however, 

 is too abstruse for these papers, and, moreover, it has no 

 weight as against the theory of derivation. We know very 

 little as to the complex conditions ruling fertility and barren- 

 ness ; we know that the reproductive organs are peculiarly 

 sensitive to altered habits and surroundings, and we know 

 further, that it is through changes in those organs that the 

 barriers to interbreeding have arisen, and the consequent mul- 

 tiplication of countless intermediate varieties been arrested.^ 

 Happily, the Darwinian theory has no fatal element of 

 rigidness in it, and those who would mould it into a dogma 

 know not what spirit they are of. It admits of alterations 

 in detail at the behest of fresh facts, and of such correction 

 of proportion as time alone gives to things new and near. 

 But the truth of the theory of which it is a subordinate 

 part will thereby stand out the clearer, and the full accord 

 of past and present to the oneness of things appear more 

 manifest. 



* " Origin of Species," p. 404. 



t "Animals and Plants under Domestication," vol. ii. pp. 130- 

 156, and chap, six., passim. 



% Haeckel's " Historj' of Creation," vol. i., pp. 145-148. 



§ No one definition of " species " has satisHed all naturalists, and 

 the term " variety" is almost equally difficult to define, but, prac- 

 tically, when a naturalist can unite by means of intermediate links 

 any two forms, he treats the one as a " variety " of the other, rank- 

 ing the most common, but sometimes the one first described, as the 

 " species," and the other as the " variety." Cf. " Origin of Species," 

 p. 33. 



