Telescopic Alidade for Plane Table with Case, by E. R. Watts & Son Ltd., 1944

Telescopic alidade for plane table with case, by E. R. Watts & Son Ltd., 1944. The alidade has a telescopic shaft with an eyepiece at one end, a lens at the other, an upwards-protruding copper alloy knob and is mounted above a sextant. Below the sextant is a moving arm with a lens. At the edge of the base, a long thin flap opens out about 45°, has a mirror on one side and reveals a horizontal spirit level. A shaft that has four protruding knobs and a vertical spirit level attaches the frontal elements to a long, thick metal rectangle with a strip that lifts up from the rest of the object but is attached via an arm at each end. It has a small ball-shaped handle for ease of lifting. A lens cap sits at the large end of the shaft. A telescope cap sits in the case, on a cylindrical holder that fits it exactly. The case is a wooden box with a hinged lid, a keyhole, hook fasteners and a leather handle at the front. The Centre of the underside of the lid has a rectangular metal plate with manufacturer information. The box has a small key.