Calotype made by Henry Collen (1800-1875) using W H Fox Talbot's (1800-1877) proces. In 1842 Collen purchased the first license from Talbot to promote calotype photography in London. Children (1777-1852) published notes on electricity and translated chemical tracts. He was the father of the pioneering photographer and botanist Anna Atkins (1799-1871) who was a friend of Talbot's.
© National Museum of Science & Media / Science & Society Picture Library