Sympiesometer formerly belonging to Walter Goodsall. Enclosed behind bevelled glass and mounted in a carved mahogany case, the instrument contains a sympiesometer, mercury barometer, thermometer, and a sliding scale. It is inscribed ‘IMPROVED SYMPIESOMETER’. A brass weight sits below the instrument to keep it steady and upright against the rolling of the ship. Sympiesometer's were lightwieght barometers, frequently used on ships in the 19th century. The sympiesometer was developed by the Edinburgh instrument maker Alexander Adie in around 1816.