Code: M25412
Stores reference 6B/218. This instrument is intended for use on aircraft for the purpose of obtaining the altitude of the sun or other celestial body and was carried on all multi-manned aircraft including wartime bombers. It is manufactured with a black painted metal case with rubber rimmed eyepieces. A black painted drum at the front houses a clockwork automatic averaging attachment. The Mark IXA sextant is built in two halves, the plane of junction being approximately down the centre, and this plane serves as the reference plane of the instrument and is the plane of the line of sight. The attachment is secured to the front by screws entering the right half of the sextant case. The left half of the sextant carries the bubble and its collimating system which together form the artificial horizon; it also carries the left handle which contains the dry battery or plug adaptor and the lighting control switch attached to the upper part of the handle. The right half of the sextant carries the sextant proper, consisting of two mirrors together with the gear for measuring their rotation, sunshades, the altitude scales and the scale lighting lamp in the right handle. The scales on the right half of the sextant show the altitude of any single observation. The clockwork driven attachment is connected to the measuring gear in the right half of the sextant and gives the average of the altitude shown on the right half of the sextant at 60 intervals of time evenly spaced over a period of approximately 2 minutes, during which the observer follows the object to be observed in the sextant, maintaining coincidence with the bubble to the best of his ability. A swivel clip is permanently affixed to the top of the instrument to enable it to be fitted to the suspension arm in the astrodome. The transport case, stores reference 6B/236, which is also intended for use as a stowage case, has space for two dry batteries, Reference 5A/2067, and a plug adaptor. This example is 1942 dated. It is somewhat soiled/marked but appears to be complete and in good overall condition. It comes with the bakelite transit/storage case which is also in good order complete with leather carry handle. The case contains the loom/plug adaptorand two plastic tubes are positioned where the batteries would fit. The clockwork averaging attachment winds and runs but we have no idea whether the sextant works but it is cosmetically at least in very good order. Stock code M25412.
