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. Insists on inclusion of all data and graphs in the publication of the accumulated magnetic observations, made as part of 'perhaps the very greatest scientific operation ... ever ... undertaken....' Urges that funding be sought from the government. 28 January 1841