# Appletons' Cyclopædia of American Biography/Rowland, Henry Augustus

Edition of 1900.
​ROWLAND, Henry Augustus, clergyman, b. in Windsor, Conn., 18 Sept, 1804; d. in Boston, 4 Sept., 1859. He was graduated at Yale in 1823, and at Andover theological seminary in 1827. During the three years following he was agent of the American Bible society in New York and Connecticut, and he was ordained in the Presbyterian church on 24 Nov., 1830. He was called to Fayetteville, N. C., in 1831, and three years later to the pastorate of the Pearl street church, New York city. In 1843 he accepted charge of the Honesdale, Pa., parish, and from 1855 till his death was pastor of the Park Presbyterian church in Newark, N. J. The degree of D. D. was conferred on him by Union college in 1853. He published many single sermons, and, besides contributions to the religious press, was the author of “On the Common Maxims of Infidelity” (New York, 1850); “The Path of Life”(1851); “Light in a Dark Alley” (1852); and “The Way of Peace” (1853). See “Memorial of the Life and Services of the Late Henry A. Rowland,” by E. R. Fairchild (New York, 1860).—His son, Henry Augustus, physicist, b. in Honesdale, Pa., 27 Nov., 1848, was graduated at Rensselaer polytechnic institute in 1870 as a civil engineer, and engaged during 1871 in the surveying of a railroad in western New York. He then taught for a time in Wooster university, but in 1872 returned to the institute as instructor in physics, becoming assistant professor in 1874. Prof. Rowland spent a year abroad studying with Helmholtz in Berlin and in examining physical laboratories in Europe. In 1876 he was invited to accept the chair of physics, with charge of the laboratory, in the newly founded Johns Hopkins university, and he has since held that place. The honorary degree of Ph. D. was conferred on him by that university in 1880. He was a member of the electrical congress that met in Paris in 1881, and served on the jury of the electrical exhibition there in that year, and fur his services was made a chevalier of the Legion of honor. Prof. Rowland is a permanent member of the International commission for establishing electrical units, is corresponding member of the British association for the advancement nf science, one of the twelve foreign members of the Physical society of London, and is an associate of the American academy of arts and sciences, from which in 1884 he received the Rumford medal for his researches in light and heat, and in 1881 he was elected to the National academy of sciences. In 1883 he presided over the section on physics of the American association for the advancement of science at Minneapolis, and delivered a valuable address entitled “A Plea for Pure Science.” His original work has been extensive, and includes numerous researches that have been made under his supervision at the Johns Hopkins. While he was in Berlin he showed experimentally that a moving charge of statical electricity has the same magnetic effect as a current. He has more recently gained reputation by his large diffraction gratings, which are ruled, by a method of his own, directly on concave mirrors. An image of the spectrum is thus produced without the aid of lenses. The photographs of the solar spectrum that he has succeeded in making with the aid of these gratings surpass anything else of the kind that has ever been done. They were exhibited to the National academy of sciences in 1883. He has also made an extremely accurate determination of the value of the ohm, the absolute unit of electrical resistance. Among his papers are “On Magnetic Permeability” (1873); “On the Magnetic Permeability and Maximum Magnetization of Nickel and Cobalt” (1874); “Studies on Magnetic Distribution” (1875); “On a Magnetic Effect of Electric Connection” (1876); “Research on the Absolute Unit of Electrical Resistance” (1878); “On the Mechanical Equivalent of Heat” (1880); “On Concave Gratings for Optical Purposes” (1883); “On the Relative Wave-Lengths at the Lines of the Solar Spectrum” (1886); and the article on “Screws” in the “Encyclopaedia Britannica”; also he has published “On the Mechanical Equivalent of Heat” (Baltimore, 1880). and “Photographs of the Normal Solar Spectrum” (seven plates, 1886).