344 THOMAS YODNG. 



The penalty of retaliation was applied to him with inter- 

 est ; the Edinhurgh Revieio attacked the man of erudi- 



upheld for what they are worth as such, the weight of a name may not 

 be imworthy of due estimation ; great experience and high genius may 

 add value to a pure Jnjpothcsis though it could not to a positive conclu- 

 sion. In regard to theories of light this has been conspicuously exem- 

 plified, and during a long continuance of controversial discussion it 

 has been a matter of triumph to the opponents of the undulatory the- 

 ory that tlie authority of Newton is on their side. And even Arago 

 as well as some other supporters of it have spoken as if regretting that 

 they were thus constrained to put themselves in antagonism to New- 

 ton. They have pictured two rival theories, the one headed by New- 

 ton and supported by Laplace, Biot, Brewster and Potter, the other 

 upheld in opposition to them bj' Huyghens, Hooke, Euler, Young, 

 Fresnel, Airy and all the Cambridge school. 



But a very slight inquiry into the real facts entirely dispels this 

 view of the case. In particular Dr. Young himself in proposing his 

 theory, so far from opposing the Newtonian views, expressly endeav- 

 ours to conciliate attention by claiming the weight of Newton's author- 

 ity 011 his own side : thus in his paper " On the Theory of Light and 

 Colours," (Phil. Trans. 1801,) he commences by highly extolling the 

 optical researches of Newton, and then observes, "those who are 

 attached, as they may be with the greatest justice, to 'every doctrine 

 which is stamped with the Newtonian approbation, will probably be 

 disposed to bestow on these considerations (i. e. his own views) so 

 much the more of their attention as they shall appear to coincide more 

 nearly with Newton's opinion." He then proceeds to examine in de- 

 tail a number of passages from Newton's writings in which the theoiy 

 of waves is distinctly upheld and even applied with some precision 

 to the explanation of various phenomena of light, illustrated by their 

 analogies to those of sound. 



It is perfectly true that Newton in the actual investigation of several 

 phenomena of light adopts other hypotheses than those of waves; and 

 chiefly the idea of light (whatever may be its nature) being subject to 

 certain attractions and repulsions, — to certain bendings when approach- 

 ing near the edges of solid bodies, — to certain peculiar modifications or 

 changes in its nature recurring periodically at certain minute intervals 

 along the length of a ray, — to the idea of a ray having " sides " endued 

 with different properties ; in a word, a variety of conceptions, which he 

 introduces for the purpose of giving some kind of imaginarj' physical 

 representation of the inodiis operandi in each of the several curious 



