Henry Sawerthal, a British photographer, came to the Cape Colony in the eighteen-eighties and by July 1887 had become a member of the South African Philosophical Society. He was still listed as a member in 1892. Sawerthal was engaged by Dr David Gill*, in charge of the Royal Observatory, Cape of Good Hope, to assist in a photographic survey of the southern sky. This project, named the "Cape Photographic Durchmusterung" (CPD), had been in progress since April 1885 with C. Ray Woods* as photographer. Sawerthal joined the project shortly after October 1887. During the next three years he and Woods made over 2500 exposures, photographing every part of the southern sky from the celestial South Pole to a declination of 18?S twice. The photographic work was completed in December 1890, at which time Sawerthal resigned.
In the course of his work on the CPD, on the morning of 18 February 1888, Sawerthal discovered a bright comet, which was named after him. It also earned him a prize of ?100, sponsored by Mr H.H. Warner of New York. His discovery was announced in "Entdeckung eines neuen Cometen... am Cap der Guten Hoffnung" (Discovery of a new comet... at the Cape of Good Hope) in Astronomische Nachrichten (1888, Vol. 118, pp. 319-320).