Henry Augustus Rowland ((November 27, 1848 - April 16, 1901) was an American physicist who served as the first president of the American Physical Society and became the first chair of the Physics department at Johns Hopkins University. He is remembered today particularly for the high quality of the diffraction gratings he made and for the work he did with them on the solar spectrum and which have been of enormous advantage to astronomical spectroscopy. He is also remembered for his re-determination of the ohm and a new determination of the mechanical equivalent of heat. Rowland was one of the most brilliant American scientists of his day, and it is sad that at his merits were not appreciated in his own country. He died of diabetes in 1901 at the age of 52.