View of the stern of 'Discovery' (1873), showing the tide gauge set up on 17 September 1875. The tide gauge consisted of a copper wire weighted at the bottom, and passing over a roller fixed to the taffrail on 'Discovery', with a 14 lb lead weight attached to the other end. A scale marked in feet and inches was fixed to the stern, with a pointer on the wire to indicate the rise and fall of the tide. Original negative scratched 'No 50' (bottom)