Copy letter, from Sir John Herschel to Richard Hodgson, 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. Charles Pritchard was wrong in ascribing priority for diagonal reflecting telescope in Pritchard's address to the Royal Astronomical Society As early as 1825, John Frederick William Herschel was first to use diagonal reflector. Describes its construction. 18 February 1864