Copy letter, from Sir John Herschel to Edward Sabine, 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. Opposes sending expensive scientific equipment for J. B. N. Hennessey to use in India; suggests instead a variety of useful observations needing to be made, using inexpensive equipment. Discusses son's [Alexander] spectroscope observations of meteors. 11 August 1866