 Ronalds went on to build and describe various different photo-recording machines in a series of reports and papers, which were employed in observatories around the world until well into the 20th century.In the late 1970s, Larry Schaaf wrote about the contributions of Henry Collen to the field of photography in its early stages in London in the 19th century.Schaaf's premise was that Collen's work was indeed noteworthy, and had perhaps been overshadowed by the earlier work of William Henry Fox Talbot in the same field.