KINETIC OR MECHANICAL VIEW OF NATURE. 19 



different colours depends on the different frequency of 

 vibrations excited by light in the retina, and " that all 

 material bodies have an attraction for the ethereal 

 medium by means of which it is accumulated within 

 their substance." In all his conclusions, while differing 

 from Newton's doctrines, he sees the strongest proofs of 

 the admirable accuracy of Newton's experiments, " but 

 scarcely any remaining hope to explain the affections 

 of light by a comparison with the motions of projectiles." l 

 Although Young thus established " a theory of the nature 

 of light which satisfactorily removes almost every diffi- 

 culty that has hitherto attended the subject," 2 his view 

 was only tardily accepted. Wolla'ston, 3 with the hesi- 

 tancy which also characterised his adhesion to the 

 atomic theory of Dalton, did not avowedly adopt Young's 

 views, though he furnished some capital experimental 

 support for the vibratory theory of light. 4 



Brougham, in the ' Edinburgh Eeview,' ridiculed 

 Young's theories, and persuaded the public that they attack on 

 stood in contradiction with Newton's discoveries, on 

 which they were really as much founded as those of 

 the opposite school. Through such disfavour, arising 

 largely from a want of skill in grasping the intricate 

 mathematical problems which were involved, the doctrine 

 of the interference of light, the mainstay of the undula- 



15. 

 Brougham's 



Young. 



1 Works, vol. i. p. 169. 



2 ' Lectures,' ed. Kelland, Preface, 

 p. ix. 



3 " Whatever disposition Dr Wol- 

 laston may have felt to view this 

 theory with favour, he was re- 

 strained from adopting its con- 

 clusions by the habitual caution 



of his character, or rather by the 

 want of that bold and enterprising 

 spirit of speculation which is more 

 or less essential to those who 

 make great revolutions in science " 

 (Peacock, ' Life of Young,' p. 375). 

 4 Ibid., p. 374. 



