Pedulum type artifical horizon.

Artificial horizon, pendulum type, by John Charles Dennis, 118 Bishopgate Street, City of London, England,1842-1849. Designed by Alexander Bridport Becher, a British naval officer, in 1834. It consists of a pendulum suspended in a brass tube filled with almond oil to dampen its motion, which is attached to the side of a sextant. A separate oil lamp can be fitted to the tube for illumination at night. In fitted rectangular case with trade label on lid, with a bottle of almond oil and spare wick for the lamp.