Sextant with illuminated reading scale - has side plate for scale graduations with illumination provided by bulb energised by small cylindrical battery

摘要

The sextant has a sector arm (1) with an altitude plate (4) attached, at the side of which is a light guide cover plate (12) with a borehole (19) for the illumination tube bulb. The plate covers the entire reading range of the scale, and has curved outer regions. The lamp tube has a rod-shaped battery at one end held down by a button plunger and with the top cap in contact with the bulb so that the positive terminal of the battery makes contact with the centre pole of the bulb. A spring completes the mechanical connection and holds the bulb in position.