Copy letter, from Sir John Herschel to Hugh Percy (3rd Duke of Northumberland), dated at Slough Copy of letter, copied as part of the correspondence project led by Colonel John Herschel FRS following the death of his father. John Frederick William Herschel has written to James South again [see John Frederick William Herschel's 1833-7-8] but has received no answer; is suggesting that it may well be that [R. A.] Cauchoix, the French optician, can supply object glasses as good as those James South has. 9 August 1833