Draft letter, from Sir John Herschel to Warren de La Rue, dated at Collingwood Draft letter. Thanks for the diary and pocket book. Sees that A. V. Guillemin has published an illustrated Astronomy [Le ciel (Paris, 1864)]. Thinks there is scope for publishing a volume of engravings of astronomical objects. Gives his own idea for the construction of a photometer. 4 December 1864