Officer pocket compass used in 1918 by British Air Force officers made of chromed brass shaped like a pocket watch. Signed Clement Clarke Ltd London VI n. 36590 1918. The compass is equipped with a lid with snap closure with release button inside the ring. Compass card with sixteen winds complete with goniometric circle for calculating horizontal angles. Excellent condition, fully functional. Measures: Diameter cm 4.5 - inches 1.77, thickness cm 2 - inches 0.78.The use of a magnetic needle is described by the Arab scientist Bailak Al Qabajaqi: in 1242 during a travel from Tripoli in Syria to Alexandria the captain of the ship used it, putting in a pail with water a piece of cork with a needle and magnetizing it with a magnet; the needle moved immediately in the North-South direction.