various journals, and also in pamphlet form, papers upon the necessity of an adequate recognition of the importance of a well-equipped physical laboratory at Harvard University.
He was editor for two years of the "Annual of Scientific Discovery," 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 measuring strong electrical currents. His next paper was upon animal electricity. The result of long investigation had deepened in him the conviction 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 torpedo 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 electrodes with fresh muscular tissue; in other words, to the fact that the so-called muscular electrical currents had their seat in the contact between 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 dynamometer, which enabled one to measure the strongest electrical current 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-
