At Tate Britain
Anne Wagner: ‘Salt and Silver’, 21 May 2015
“... and both echo principles shared with them by a third experimenter, the chemist and astronomer Sir John Herschel. It was Herschel who first used ‘negative’ and ‘positive’ to name the two distinct stages of photographic depiction, and Herschel whose investigations ultimately made it possible to capture the vagaries of light. In brief, what Herschel ... ”