Copy letter, from Sir John Herschel to Edward Sabine, dated at Collingwood Copy of a letter. Has signed certificate for [W. F.] Hook. [See Edward Sabine 1861-12-5] Congratulates Edward Sabine [on presidency of Royal Society [of London]]. John Frederick William Herschel on B.A.A.S. balloon committee. Proposes design for metallic 6 December 1861