90 PROCEEDINGS OF THE ALBANY MEETING 



Meanwhile he was active in the Field Naturalists' Club, and said in 

 writing of their meetings : 



"It is good to be a specialist, but it is also good to know of other things than 

 one's own specialty." 



The study of some octahedral crystals of magnetite leads him to Avrite: 



"They give one a concrete conception of the fact that the principles of 

 mathematics are not the device of man." 



At the same time he was working in the physical laboratory, deter- 

 mining the wave-lengths of light by means of Rowland^s diffraction 

 gratings. 



There is no evidence that Hayes had any very definite plans for the 

 study of geology when he went to the Hopkins. His interest in the 

 science appears to have been aroused by the excursions of the Field Club, 

 which brought him in contact with Williams. Previous to this time his 

 taste and training were all for and in the exact sciences of mathematics, 

 chemistry, and physics. It was probably the realization that geology, 

 through mineralogy and crystallography, led back into his own field and 

 his love of an outdoor vocation that brought him to the science the ad- 

 vancement of which was to constitute his life's work. 



In November, 1884, he had his first geologic work, of which he says: 



"I began today Doctor Williams's lectures on geology and wish I had begun 

 sooner; can't afford to miss them." 



And, again, in a later letter : 



"We are working now in dynamical geology and are buried deep in volca- 

 noes." 



He records his introduction to microscopic petrography : 



, . . "It is just the toughest thing I ever got hold of, and I do not propose 

 to be beaten by it." 



He still, however, devoted most of his energies to the exact sciences, 

 and his interest in geology was that of the chemist and physicist. After 

 hearing Sir William Tliompson's lecture on the rigidity of tlie eai-tli's 

 crust, he writes : 



"I can not say that T apprehend all of nis points, but the argument seems 

 good. I am reading some of Fisher's Physics of the Earth's Crust. He takes 

 a very different view from Sir William Thompson. . . . The weakness of 

 the physicists' position is that they are working on inadequate datn. . . . 

 When they base such conclusions as they do on the tides, they should have 



