10 SCIENCE: J. J. CARTY 



teacher at the Albany Academy, professor at Princeton, the first 

 Secretary of the Smithsonian Institution, and President of the 

 National Academy of Sciences. No controversy arose between 

 Faraday and Henry as to the credit for the discovery, but with that 

 generosity of spirit which characterized them both, each gave a full 

 measure of credit to the other. Indeed, this discovery tended to 

 form a bond of union and became the source of a permanent friend- 

 ship between them. By agreement among the scientists of all the 

 nations, one of the fundamental electrical units is called the 

 "farad," in honor of Faraday, and another is called the "henry" 

 in honor of Henry. Both of these men devoted their lives to the 

 discovery of new scientific truths, and to the teaching of science. 



To them, as to all workers in pure science, "What use is it?" 

 is not the vital question, but rather, "What message does it bring? 

 What truth does it reveal? What law does it establish?" 



An experiment in science is but a question put to nature. She 

 will answer truthfully every question that we ask. She will make 

 known to us all her secrets if we have but the skill properly 

 to frame our questions and the wit to appreciate the answers. 



An English statesman before whom Faraday performed his 

 fundamental experiment in electromagnetism asked the forbidden 

 question "What use is it?" Faraday replied, "Some day it may be 

 developed so that you can tax it." 



Faraday was a good prophet, for upon his fundamental dis- 

 covery and that of Henry, if I may but include one or two others 

 of a similar fundamental character, there has been erected the entire 

 art of electrical engineering, as it exists throughout the world to- 

 day. Truly this discovery has been developed. To-day mankind 

 is in possession of electrical property valued at twenty billions of 

 dollars and evidence is not lacking that other statesmen besides 

 Faraday's are busy taxing it. 



It is my great privilege to have here the identical apparatus 

 employed by Henry, and with this to perform before you to-night 

 the experiment illustrating the fundamental principle in electro- 

 magnetism discovered by Faraday and Henry. In this experiment, 

 an electromagnet (see Fig. i) is made to generate a current of 

 electricity in a coil of wire, as is proven by the deflection of the 

 galvanometer (see Fig. 2). The principle thus discovered is the fun- 

 damental one upon which all dynamo-electric machines are built. 



The coils of these magnets and this galvanometer were 



