6 MR. J. SMITH ON THE ORIGIN OF COLOUR 



latter, and indeed is so more frequently;, when applied to 

 subjects of natural philosophy. 



6. To investigate the physical nature of light, to inquire 

 whether the corpuscular or the undulatory theory be true, 

 may by some be considered as a purely speculative or 

 metaphysical discussion resulting in no practical benefit. 

 It matters not, it is said, as far as mathematics are con- 

 cerned, whether light is an emanation of particles from 

 the luminous body, or the undulations produced by the 

 same body in a highly elastic medium, " for the principal 

 phenomena of light are deducible by strict mathematical 

 reasoning from either supposition." But until mathema- 

 tics shall be proved to be the only true basis of physical 

 reasoning, such an argument for resting satisfied with 

 what knowledge we have of the nature of light is not at 

 all creditable to science. True philosophy in process of 

 time leads to grand universal laws; false philosophy, or 

 suppositions however ingenious, lead to partial, excep- 

 tional and restricted views. Galileo when he was demon- 

 strating by the use of his telescope that the planet Venus 

 had phases similar to those of our moon, and was conse- 

 quently illuminated by the light of another body and not 

 shining by its own, was doubtless considered by the phi- 

 losophers of the age as being engaged in a much more 

 sublime investigation, because a more popular one, than 

 when he was demonstrating the law of falling bodies. 

 For little was it thought that by solving the problem of 

 the pendulum he was solving the most comprehensive 

 problem ever solved; that he was teaching to another 

 great investigator the method whereby he was not only to 

 dissipate the mystery of planetary motion but to weigh 

 the matter of the universe itself. 



If then, mathematically, it be a matter of indiflPerence 

 what is the true nature of light, it is not so philosophically. 

 What tends to elucidate the true nature of light, may 



