Henry Fox TalbotDied 17 Sep 1877 at age 77 (born 11 Feb 1800).William Henry Fox Talbot was an English inventor, mathematician, chemist, physicist, philologist and Egyptologist who invented the negative-positive photographic process. He improved the discovery by Thomas Wedgwood (1802) that brushing silver nitrate solution onto paper produces a light-sensitive medium able to record negative images, but Wedgewood was unable to control the darkening. In February 1835, Talbot found that a strong solution of salt fixed the image. Using a camera obscura to focus an image onto his paper to produce a negative, then - by exposing a second sheet of paper to sunlight transmitted through the negative - he was the first to produce a positive picture of which he was able to make further copies at will. His Pencil of Nature (1844) was the first photographically illustrated book.