410 LEADING AMERICAN MEN OF SCIENCE 



vacuum tubes by boiling mercury in tubes and sealing them up 

 while boiling." 



"June, 1866: Obtained a law that the mechanical equivalent 

 of electricity is equal to its quantity multiplied by its intensity." 



A note added in 1900, reads: 



"By 'intensity' I meant tension or potential. Therefore the 

 above is correct." 



"February, 1868: Made very delicate astatic galvanometer. 

 Used it for magnetic permeability experiments." 



"September, 1868: Invented dynamo armature. The first con- 

 tinuous current armature ever made." 



While in his seventeenth year, in the early autumn of 1865, 

 Rowland wrote a letter to The Scientific American and much to 

 his surprise this was printed. He says of it: "I wrote it as a kind 

 of joke and did not expect them to publish it." This was his first 

 appearance in print. Six years later he sent another paper to 

 The Scientific American this time a serious one. It was a criti- 

 cism of an invention which was in conflict with the law of the 

 Conservation of Energy. In this communication he displayed 

 those qualities of mind which appeared in all his later work. Just 

 after he returned to the Rensselaer Polytechnic Institute he pub- 

 lished an article on "Illustrations of Resonances and Actions of a 

 Similar Nature." This appeared in the Journal of the Franklin 

 Institute. 



No attempt will be made in this article to give a complete 

 account of Rowland's scientific work, but it is necessary to refer 

 to his most important contributions. One of his early experiences 

 was discouraging, but out of it came encouragement. He had 

 been for some time engaged in a research on the magnetic per- 

 meability and the maximum magnetization of iron, steel, and 

 nickel, when he brought his results together and sent the article 

 to a well-known American scientific journal for publication. He 

 writes to his sister June 9, 1873: "I have just sent off the results 

 of my experiments to the publisher and expect considerable from 

 it; not, however, filthy lucre, but good, substantial reputation." 



