He was born on December 8, 1856, in
Baltimore, the son of the physician
Christopher Johnston (1822-1891), a professor of surgery at the
University of Maryland and the discoverer of
Johnston's organ, and Sarah Lucretia Clay (1835-1879). Johnston married Madeline T. Tilghman on June 2, 1897, and had a son, Benamin Johnston, and a daughter, Eliza Gates Johnston, who died young. Johnston died at his home in Baltimore on June 26, 1914. ==Studies and career==