Copy letter, from Sir John Herschel to Hugh Percy (3rd Duke of Northumberland), dated at Slough Copy of a letter. 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