THE OLD ROYAL OBSERVATORY CONICAL PENDULUM CLOCK.1983 National Maritime Museum issue. Spring drive with fusee movement designed by Richard Elliott, FBHT, made by Thwaites and Reed of London; limited production of 1000, fully subscribed at $2,500; with moon phase dial, large glass dome to view conical pendulum motion; ball foot; sun and moon motif dial - 26 in. high. Estimate $400-800