80 BULLETIN OF THE 



Mr. G. K. Gilbert made a communication on 



THE DISTRIBUTION OP THERMAL SPRINGS IN THE UNITED STATES. 



107th Meeting, May 20, 1876. 



The President in the Chair. 



Thirty-four members and visitors present 



Mr. Joseph Henry exhibited and described one of 



crooke's radiometers. 



He had, however, only received it the day before, and had not 

 had an opportunity of making any experiments with it except 

 those of the most obvious cliaracter. His object in bringing it 

 forward at this time wsiS that it would interest the Society, and 

 he would probably be absent during the remainder of the session. 

 He thought Mr. Crookes, like Galvani, had commenced to in- 

 vestigate a phenomenon of which the cause was easily recognized, 

 and ended in discovering a fact of great perplexity, of which the 

 rationale, he thought, was not readily understood ; that it was 

 not a case of simple collision of elastic bodies in accordance 

 with the dynamic theory of gases, since the revolution was appa- 

 rently in the wrong direction. 



Mr. W. B Taylor remarked that in regard to this very strik- 

 ing experiment, he did not see how there could be any serious 

 doubt as to the character of the energy displayed. All sugges- 

 tions as to the possible action of "Light" in the case appeared 

 to him to quite ignore the only just conception or rational defini- 

 tion of that agency admissible — as the medium of vision. " Liglit" 

 is obviously a subjective or physiological phenomenon, and not a 

 dynamic one; merely a peculiar impression of wave-periodicity 

 on a highly specialized nerve structure. And while we have its 

 various affections in phosphorescence, fluorescence, polarization, 

 absorption, and measure its intensity in photometry, yet these 

 effects all relate to, and terminate in, the seeing eye And with- 

 out an eye, there can be no such thing as "light." 



