4” diameter prismatic surveying compass signed on the lid (not shown) F B & S (1932) Ltd with a broad arrow and B 2163. Aluminium compass ring divided to 30 minutes. Case stamped GBO over 1 in a circle. There is a tripod socket under the base. Possibly made by Francis Barker & Son (1932) Ltd., as the lid is aluminium and the rest is brass so the lid may have been changed.