Correspondence regarding clocks and chronographs, including correspondence with the Japanese Consul and E. Dent and Co. on a chronograph for the Japanese Government, 1880; and correspondence relating to various inventions associated with clocks, 1886-1937, including Mr Schoof's gravity escapement (1897), the Synchronome Co. Ltd's synchronised pendulum (1937), Mr Gordon's pneumatic clock system (1886), and R.W. Nichol's pendulum (1913).