SKETCH OF HENRY AUGUSTUS ROWLAND. 113 



was able to converse witli one who knew more about his favorite 

 subjects than he did. The wonderful and profound knowl- 

 edge of Clerk Maxwell, combined with a childish simplicity and 

 the kindliest of natures, made a great impression on Prof. Row- 

 land. 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 Helm- 

 holtz. 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 sin- 



FlKST CoNTINUOUS-ClKKKXT ArMATURE, MADE BY PrOB'. KoWLAND IN 1869. 



cerely 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 ex- 

 periments 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 determi- 

 nation of the unit of electrical resistance, the ohm, which dem- 

 onstrated 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 pro- 

 tested 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, 



VOL. XLIX. — 10 



