Bill, William Ladd, instrument maker, 11 & 12 Beak Street, Regent Street, London, to the Royal Society For 'use of 40 cell Groves battery aciids &c., with Mr. Spottiswoode's apparatus' [for the Royal Society conversazione]. Total £1.10s.0d., signed as received by William Ladd. The engraved bill-head features the company address and London and Paris prize medals for 1862 and 1867. By appointment to the Royal Institution of Great Britain. 26 April 1870