Copy letter, from Sir John Herschel to Herbert Spencer, 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. In response to Herbert Spencer's query [1864-3-1] about the influence of Auguste Comte on English scientists, John Frederick William Herschel refers Herbert Spencer to John Frederick William Herschel's 1845 B.A.A.S. presidential address. States that calculating the motion of a projectile through a resisting medium is extremely difficult. 9 March 1864