KINETIC OR MECHANICAL VIEW OF NATURE. 17 



the theory of vibrations had already achieved so much. 

 He was thus more interested in the physical nature than 

 in the geometrical properties of rays of light. He was 

 impressed by the analogies which exist between many 

 phenomena of sound and light, and acquainted with the 

 writings of the Continental mathematicians, among whom 

 Euler was conspicuous as favouring the undulatory or 

 ether theory of Huygens. He noticed that in Newton's 

 writings were to be found the germs of both theories, 

 also that the arguments by which Newton convinced him- 

 self that a theory of undulations could not explain the 

 rectilinear propagation of light, were untenable. 1 On re- 

 flecting in May 1801 on Newton's beautiful experiments, 



Voice. . . . When I began the out- 

 line of an essay on the human voice, 

 I found myself at a loss for a per- 

 fect conception of what sound was, 

 and during the three years that I 

 passed at Emmanuel College, Cam- 

 bridge, I collected all the informa- 

 tion relating to it that I could 

 procure from books, and I made a 

 variety of original experiments on 

 sounds of all kinds, and on the 

 motions of fluids in general. In 

 the course of these inquiries I 

 learned to my surprise how much 

 further our neighbours on the 

 Continent were advanced in the 

 investigation of the motions of 

 sounding bodies and of elastic fluids 

 than any of our countrymen ; and 

 in making some experiments on the 

 production of sounds, I was so 

 forcibly impressed with the resem- 

 blance of the phenomena that I saw 

 to those of the colours of thin plates, 

 with which I was already acquainted, 

 that I began to suspect the exist- 

 ence of a closer analogy between 

 them than I could before have 

 easily believed " (p. 199). This led 



VOL. II. 



to his ' Outlines of Experiments 

 and Inquiries respecting Sound and 

 Light ' (ibid., p. 64). 



1 Works, vol. i. p. 200. " New- 

 ton's arguments from experiment 

 appear to me to have been suffi- 

 ciently obviated by what Lambert 

 has advanced in the ' Memoirs of 

 Berlin. ' . . . The demonstration is 

 attempted in the ' Principia' : to me 

 it appears to be defective. . . . 

 The celebrated Laplace, in com- 

 paring the opinions respecting 

 light, is contented to call the 

 Newtonian doctrine a hypothesis, 

 which, on account of the facility 

 of its application to the phenomena, 

 is extremely probable. If he had 

 considered the undulatory system 

 as demonstrably absurd, he would 

 not have expressed himself in so 

 undecided a manner. . . . Much 

 as I venerate the name of Newton, 

 I am not therefore obliged to be- 

 lieve that he was infallible. I see 

 . . . with regret that he was liable 

 to err, and that his authority has, 

 perhaps, sometimes even retarded 

 the progress of science," &c., &c. 



B 



