Page:Popular Science Monthly Volume 49.djvu/125

Rh was able to converse with one who knew more about his favorite subjects than he did. The wonderful and profound knowledge of Clerk Maxwell, combined with a childish simplicity and the kindliest of natures, made a great impression on Prof. Rowland. He looks back to this visit as one of the most notable events of his life. From England he went to France, thence to Germany, where he entered the laboratory of Baron von Helmholtz. It was here he carried out his research on the magnetic action of electric convection—an idea he had conceived in 1868 while reading Faraday's Researches. He returned to America in 1876, and assumed his duties as Professor of Physics in the Johns Hopkins University.

Prof. Rowland was at this time only twenty-seven years of age, a period at which many of his graduate students now begin the study of physics under his able tutelage. His students are sincerely



attached to him, and have so profound a respect for his knowledge and ability that many of them emulate his example and gladly spend hours of extra time in testing interesting experiments suggested by his lectures.

During the early years of Prof. Rowland's life in Baltimore he made a new determination of the mechanical equivalent of heat, in which he introduced exact thermometry for the first time. He made a considerable correction in Joule's value. He also discovered that water had a minimum value of its specific heat, a fact unnoticed before. Soon after he made a determination of the unit of electrical resistance, the ohm, which demonstrated the error of the British Association Committee. This experiment he repeated with a Government appropriation as a member of the International Congress for fixing this standard. When this congress met at Paris, in 1884, Prof. Rowland protested against the value there adopted, as it did not agree with his experiment. At the Congress of Electricians, held at the Centennial Exposition at Chicago, in 1893, the International Chamber of Delegates, of which Prof. Rowland was president,