Copy letter from Herbert Rix, to N H J Miller, Harpenden, St Albans 'Dear Sir, The lantern shall be ready for Dr Gilbert on the 9th. The largest size slide which the lantern takes is 4 1/4 x 3 1/2 in [inches]. We have carriers also for the smaller sizes. Yours faithfully, H Rix Asst Sec RS [Assistant Secretary, Royal Society]'. 2 January 1890