Mariners began to use barometers in the 18th century to predict changes in the weather, but it was in the 19th century that their use at sea became widespread. This marine stick barometer has a mahogany case and brass gimbals that allow it to remain level when used on a ship at sea. The barometer scale is marked in inches of mercury and has a vernier moved by an ivory knob to allow accurate reading of the scale. The cistern for the mercury in the barometer is visible at the bottom. A thermometer is housed in the centre of the instrument and has a scale in Fahrenheit, with additional indications of 'Temperate', 'Sumr. Heat' and 'Blood Heat'. The name 'COUSINS SWANSEA' on the barometer scale may be either the maker or the retailer of the instrument.