British astronomer and instrumentmaker
who pioneereed celestial photography. Besides inventing the first photoheliographic
telescope, he took the first photograph of a solar eclipse 1860 and
used it to prove that the prominences observed during an eclipse are
of solar rather than lunar origin.
De la Rue was born in Guernsey and joined his father in the printing
business. He was one of the first printers to adopt electrotyping and
in 1851 he invented the first envelope-making machine. He also invented
the silver chloride battery.
De la Rue's interest in new technologies led him to apply the art of
photography to astronomy. He modified his 33-cm/13-in telescope to incorporate
a wet collodion plate. His first photographs were of the Moon, and their
success encouraged him to build and equip a new observatory in Cranford,
There, de la Rue began a daily sequence of photographs of the Sun. He
designed a photoheliographic telescope to take to Spain for the 1860
eclipse, after which it was set up at the Kew Observatory, London. He
used it to map the surface of the Sun and study the sunspot cycle. This
work led to his being able to show that sunspots are in fact depressions
in the Sun's atmosphere.