# Popular Science Monthly/Volume 26/April 1885/Sketch of Professor John Trowbridge

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JOHN TROWBRIDGE.
* SKETCH OF PROFESSOR JOHN TROWBRIDGE.
PROFESSOR TROWBRIDGE is the son of a physician, and was born in Boston in 1843. He prepared for Harvard University at the Boston Latin School, but did not join the Freshman class. He entered the Lawrence Scientific School, from which he was graduated in 1866. He was tutor in the Scientific School for the two years succeeding his graduation, and was appointed Assistant Professor of Physics in the Massachusetts Institute of Technology in 1868. In 1870 he was called to Harvard University as Assistant Professor of Physics to establish a laboratory course of instruction. He obtained the degree of Doctor of Science from Harvard in 1873. For the past six years he has been Professor of Experimental Physics in the university.
The descent and early education of scientific men have lately become the subject of investigation by Galton. None of the ancestors of Professor Trowbridge evinced any scientific tastes, although there were several who had strong literary tastes and also legal ability. Professor Trowbridge's father, believing in the adage of Bacon, that a boy, if given the range of a library, will select the food most suitable to his tastes, provided him liberally with books, but not with instructors; and, being fond of art himself, stimulated a certain fondness for drawing in the child. The consequence of this training was that, when the boy at the age of fourteen or fifteen entered the public schools, he had a large amount of desultory information in literature and a facility for drawing, but no systematic training in languages or in mathematics. While, however, many of his comrades who had been carefully trained in schools from an early age grew tired of intellectual effort, he came to the subjects of mathematics and the sciences with a certain freshness which might not have survived too much school-culture at an early age. His strong taste for art made his friends predict an artistic career as the only one suitable for him. His graduation at the Lawrence Scientific School with the degree of Summa cum Laude, and the evidence of strong mathematical tastes, determined his future career.
When Professor Trowbridge came to the university in 1870 as a teacher, the subject of physics was taught merely by lectures and recitations. He immediately secured a small room and fitted it up as a physical laboratory. From this small beginning arose, through his constant endeavor, the Jefferson Physical Laboratory, which is the largest laboratory of the kind at present in America. In order to secure this great means for advancing the study of physical science in the university. Professor Trowbridge has given his best efforts for the past ten years in the direction of personal solicitation, and by publishing in ​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 ​magnetism must be attributed to induced currents in the iron or steel, rather than to reversals of magnetism in molecular magnets. A later investigation upon the same subject tends to confirm the above result.
Among the instruments invented by Professor Trowbridge may be mentioned a new form of induction-coil, in which the primary coils are employed, and two induction-coils, the poles of the electro-magnets being connected by thin plates of iron. The spark produced from this combination by a mechanical break has great heating effect.
The active duties of a college professor leave little time for continued systematic investigation. A new era, however, is dawning in university education in America, and the college professor who shows ability for scientific investigation will undoubtedly be relieved of the yearly teaching of immature minds and be left free to devote himself to graduate students, to research, and to the general supervision of his department, rather than to the daily drill which should be left to trained assistants. Notwithstanding his full duties as a professor, Professor Trowbridge has published each year various investigations from the Physical Laboratory of Harvard University, which up to the present time has consisted of merely one room, inadequately fitted up for scientific work. In these investigations he has been often assisted by students. Among his researches are papers on the conveyance of heat by the electrical current in various metals, particularly in nickel; a paper written in association with Mr. C. B. Penrose, on the availability of a thermal junction for measuring very low temperatures; on the formation of vortex-rings in liquids, and an interpretation of the mathematical formulae relating to vortex rings in water; a paper by himself and Mr. Penrose, on the propagation of heat at right angles to, and in the direction of, the lines of magnetic force; a study of the effect of displacement of the compass in the Helmholtz's form of Gaugain galvanometer; a paper on the cause of the disturbances heard on telephone-lines, in which it was shown that a large part of their disturbances is due to the battery—earth. A survey of the country about Cambridge showed that the time-signals of the Harvard College Observatory were transmitted through the earth over a great extent of territory. This survey suggested to Professor Trowbridge the possibility of telegraphing across large bodies of water without a wire. Mr. Preece, of the London telegraphic system, acting upon the suggestion of Professor Trowbridge, succeeded in transmitting telegraphic signals from Southampton to the Isle of Wight, without a wire. Professor Trowbridge has also published various papers on thermo-electricity, a subject which has occupied his thoughts for many years.
The condition of the teaching of physics in the secondary schools having been brought to his attention by the want of preparation in this subject of students who present themselves for entrance to the university, Professor Trowbridge has prepared a treatise on ​experimental physics, entitled "The New Physics," in which modern views of the great subject of physics are inculcated through the means of elementary laboratory work. He has also contributed various essays to the "Atlantic Monthly," one of which, entitled "The Dream of Life," is an argument, ad hominem, in favor of the option of scientific studies by students who desire to enter the university without Greek. His contributions to "The Popular Science Monthly" treat of various subjects, among which may be mentioned: *' Science from the Pulpit"; "On the Teaching of Physics in the Secondary Schools"; "On the Use of Electric Lights for Steamships." In the latter paper, Professor Trowbridge advocated the use of the electric light for a head-light. Practical navigators, however, assert that such light is not to be recommended, for its dazzling glare confuses the eyes of the steersmen of approaching vessels.
His address before the American Association for the Advancement of Science was upon the question, "What is Electricity?" and, in reading it, one can discover the directions in which the author has investigated. The life of an investigator is an arduous one; but few of the ideas which take months to investigate give what are called positive results. Faraday, it is true, gave to the world the history of both his successful experiments and his unsuccessful ones. It is not the custom, however, of later physicists to do this. Scientific literature is already voluminous, and this reticence of scientific men is perhaps a boon to those who desire to look up any subject. With the increased facilities which the new laboratory at Cambridge will give, Professor Trowbridge enters upon a fresh scientific career in the prime of life, and there is reason to hope that many positive results to science will accrue from his future labors.
He is a member of the American Academy of Arts and Sciences, of which he was secretary from 1879 to 1884; he is also a member of the National Academy of Sciences. He is one of the editors of the "American Journal of Science." He was a member of the International Congress of Electricians which met in Paris, in 1883, and of the United States Congress of Electricians which met in Philadelphia last October. He was also one of the Vice-Presidents of the American Association for the Advancement of Science for 1884, at the Philadelphia meeting.