Salt paper print from a calotype negative by William Henry Fox Talbot (1800-1877). This is one of several group portraits Talbot did between 1840-1843, his most prolific period. Talbot invented the negative/positive process for producing photographs between 1835-1839, patenting it as the calotype process in 1841. For the first time any number of prints could be made of a single image from the negative.
© National Museum of Science & Media / Science & Society Picture Library