Copy letter, from Sir John Herschel to William Henry Fox Talbot, dated at Collingwood Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. Congratulates William Henry Fox Talbot on the calotype invention and the patent. Responds at some length to William Henry Fox Talbot's concerns about the infinity of the universe. In postscript, provides a 4-page dialogue on the subject. 22 March 1841