Copy letter, from Sir John Herschel to Roderick Impey Murchison, 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. Appreciates foresight, but cannot commit to be president of B.A.A.S. meeting at Cambridge in summer of 1846. Date is too far away; personal and domestic commitments are pressing. 17 April 1844