CONFIRMATION OF THE UNDULATORY THEORY. 120 



the time of Young and Fresnel, the cultivators of this theory have 

 been led to make respecting the mechanical constitution of the ether, 

 and the forces by which transverse vibrations are produced. It was 

 natural that various difficulties should arise upon such points, for trans- 

 verse vibrations had not previously been made the subject of mechani- 

 cal calculation, and the forces which occasion them must act in a 

 different manner from those which were previously contemplated. 

 Still, we may venture to say, without entering into these discussions, 

 that it has appeared, from all the mathematical reasonings which have 

 been pursued, that there is not, in the conception of transverse vibra- 

 tions, anything inconsistent either with the principles of mechanics, or 

 with the best general views which we can form, of the forces by which 

 the universe is held together. 



I willingly speak as briefly as the nature of my undertaking allows, 

 of those points of the undulatory theory which are still under delibe- 

 ration among mathematicians. "With respect to these, an intimate 

 acquaintance with mathematics and physics is necessary to enable any 

 one to understand the steps which are made from day to day ; and still 

 higher philosophical qualifications would be requisite in order to pro- 

 nounce a judgment upon them. I shall, therefore, conclude this sur- 

 vey by remarking the highly promising condition of this great depart- 

 ment of science, in respect to the character of its cultivators. Nothing 

 less than profound thought and great mathematical skill can enable 

 any one to deal with this theory, in any way likely to promote the in- 

 terests of science. But there appears, in the horizon of the scientific 

 world, a considerable class of young mathematicians, who are already 

 bringing to these investigations the requisite talents and zeal ; and who, 

 having acquired their knowledge of the theory since the time when its 

 acceptation was doubtful, possess, without effort, that singleness and 

 decision of view as to its fundamental doctrines, which it is difficult for 

 those to attain whose minds have had to go through the hesitation, 

 struggle, and balance of the epoch of the establishment of the theory. 

 In the hands of this new generation, it is reasonable to suppose the 

 Analytical Mechanics of light will be improved as much as the Analy- 

 tical Mechanics of the solar system was by the successors of Newton. 

 We have already had to notice many of this younger race of undula- 

 tionists. For besides MM. Cauchy, Poisson, and Ampere, M. Lame 

 has been more recently following these researches in France." In 



a5 Prof. Lloyd's Report, p. 392. 

 VOL. II 9. 



