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. Edward Sabine has been forwarded letter explaining why 'great telescope' at Melbourne will not work and suggesting construction corrections, on which John Frederick William Herschel, who believes such 'a priori condemnation' unjustified, comments herein. 28 April 1870