SKETCH OF PROFESSOR JOHN TROWBRIDGE. 837 



various journals, and also in pamphlet form, papers upon the necessity 

 of an adequate recognition of the importance of a well-equipped phys- 

 ical laboratory at Harvard University. 



He was editor for two years of the " Annual of Scientific Discov- 

 ery," published by Gould & Lincoln, of Boston — a publication which 

 • was a pioneer in the effort to make the results of science available to 

 the general reader. 



The first scientific paper of Professor Trowbridge was upon a new 

 form of galvanometer, which he entitled the " Cosine Galvanometer." 

 Before the invention of this instrument the tangent galvanometer and 

 the sine galvanometer were the only forms of galvanometer known in 

 scientific literature. The cosine galvanometer, which made use of 

 the principle of a vertical coil, movable about a horizontal axis, gave 

 an additional adaptation, and affords a convenient method of meas- 

 uring strong electrical currents. His next paper was upon animal elec- 

 tricity. The result of long investigation had deepened in him the con- 

 viction that the observations of Du Bois-Reymond had not established 

 the existence of so-called muscular electrical currents. The operation 

 of detaching a muscle from its position and examining its electrical 

 condition by means of a galvanometer must result in experimental 

 errors which have hitherto masked any electrical currents due to the 

 generation of electricity in the muscle itself. It is true that the tor- 

 pedo and few electrical fishes can generate electricity ; but in these 

 animals certain organs for the generation of this electricity have been 

 discovered, and this is not true of the ordinary muscle. The effects 

 observed are due to the contact of the so-called non-polarizable elec- 

 trodes with fresh muscular tissue ; in other words, to the fact that the 

 so-called muscular electrical currents had their seat in the contact be- 

 tween the electrodes and the fluids of the fresh muscle. These results, 

 being in opposition to the belief of the leading German physiologists, 

 were not accepted. Since the publication of Professor Trowbridge's 

 paper, however, prominent German physiologists have taken the same 

 view. He was one of the first to measure the relative efficiency of 

 various forms of dynamo-electric machines. His experiments were 

 conducted at the United States Torpedo-Station at Newport, Rhode 

 Island. For this purpose he invented a new form of electrical dyna- 

 mometer, which enabled one to measure the strongest electrical cur- 

 rent without subdividing it. 



In the course of this investigation, being struck with the large 

 amount of heat developed by the reversals of magnetism in the core 

 of an electro-magnet, he undertook a separate investigation together 

 with the chemist of the Torpedo-Station, Mr. Walter N. Hill, upon 

 the amount of this heating, in a great variety of steels of different 

 composition, in the hope of arriving at a practical method of testing 

 the composition of steel. The results of the investigation tend to 

 strengthen the general belief that the heat due to the reversal of mag- 



