Henry Augustus Rowland

The American physicist Henry Augustus Rowland (1848-1901) made fundamental contributions to magnetism and to celestial physics.

Henry Augustus Rowland was born on Nov. 27, 1848, in Honesdale, Pa., the descendant of a long line of clergymen. He studied at Phillips Academy, Andover, Mass., and then graduated from the Rensselaer Polytechnic Institute with a degree in civil engineering. During the next 2 years he did some work in his profession and taught natural science at Wooster University, Ohio. In the spring of 1872 he returned to Rensselaer as instructor in physics. While at Rensselaer he published an important paper on magnetism which brought him favorable attention from the English physicist James Clerk Maxwell and an appointment as professor of physics at the newly established Johns Hopkins University, designed to be the model of a graduate school. This early paper brought lasting fame to Rowland, for it proved to be the starting point for all calculations for the design of dynamos and transformers.

One of Rowland's first actions upon arrival at Johns Hopkins in 1875 was the development of a workshop in which the apparatus for fundamental research could be produced; the machines that he himself devised were among his most valuable contributions to science. Becoming interested, for example, in the spectrum of the sun and the spectra of the elements, he designed a ruling machine to produce gratings for spectrum analysis more accurate than any previously known. Dissatisfied with the results obtained with the plane gratings of Joseph von Fraunhofer and Ernest Rutherford, he combined the principle of the grating with that of the concave mirror, eventually producing concave gratings of about 100,000 lines of 6 inches in length. With these superb diffraction gratings which split light into its components, he mapped the solar spectrum more thoroughly than anyone before him had done. Making possible the direct photography and higher resolution of spectra of the heavenly bodies, this work started a new era in spectroscopy. In 1888 he published Photographic Map of the Normal Solar Spectrum.

In the field of measurements, in addition to his work on spectra, Rowland obtained long-accepted values for the mechanical equivalent of heat, the ohm, and the ratio of the electric units and the wavelengths of various spectra. In most cases, he designed his own measuring instruments.

Although Rowland had an engineer's training and always remained interested in practical applications--among his inventions was a printing telegraph and several other commercial instruments--he was primarily known as an ardent campaigner for the importance of basic research, and from his post at Johns Hopkins he trained many students who were imbued with this viewpoint. He was the first president of the American Physical Society. Rowland was married to Henrietta Troup Harrison of Baltimore in 1890. He died of diabetes on April 16, 1901.

Further Reading

• The only biographical account of Rowland is Thomas C. Mendenhall's memoir, which appears in Mendenhall's edition of The Physical Papers of Henry Augustus Rowland (1902), in the Biographical Memoirs of the National Academy of Sciences, vol. 5 (1905), and is reprinted in Bessie Zaban Jones, ed., The Golden Age of Science: Thirty Portraits of the Giants of 19th-Century Science by Their Scientific Contemporaries (1966). A profile of Rowland and an interesting selection of documents and letters are in Nathan Reingold, ed., Science in Nineteenth-century America: A Documentary History (1964).