The correspondence concerns the Royal Society's involvement in the Trigonometrical Survey. There are two unsigned draft or copy letters by Banks, dated 1817 and 1819. These concern the needs of the Survey and of Henry Kater's pendulum experiments in particular. A letter from Lord Sidmouth, dated 1818, concerns the expenses of the Survey. A letter from Mr Jennings, a compass maker, dated 1819, requests permission to use the Royal Society's magnet.