The Lens is marked ZBA0715.1, the Lens Cap is marked ZBA0715.2 and the Box is marked ZBA0715.3. Lens with variable focus possibly used in the astrographic survey or for making prints of the astrographic survey images. Can vary the f-number from 4, 5.6, 8, 11, 16, 22. Inscription on the lense reads 'No 69551 Ross, London/ No 3A/ Portraits'. The lens cap has a wooden handle. This type of lens would have been used by photographers primarily rather than as a tool solely for astronomers.