Asaph Hall Jr (1859-1930), US astronomer. Hall, also known as Asaph Hall IV, was the son of Asaph Hall III, who discovered the moons of Mars in 1877. Hall Jr studied at Harvard and Yale, and in 1892 he became director of the observatory at the University of Michigan. Following this, he became professor of mathematics in the US Navy, attaining the rank of Commander and working at the US Naval Observatory. Hall's work included studies of Titan and Saturn. This photograph, from the Harris and Ewing Collection, dates from between 1905 and 1945. The collection consists mostly of photographs taken in Washington DC, USA.