Hello Jay,

I can add a bit to that. The Germans had also developed the SOLD sextant, which was designed and produced by C.Plath of Hamburg - the oldest sextant manufacturing firm in the world. There were two types of SOLD sextants, each of them providing an "artificial horizon" which allowed the Obersteurerman to take observations at any time of the day or night: the gyroscopic horizon and the spirit level, or "bubble" horizon. Under normal circumstances, the navigator brings the sun or other celestial body down to "kiss" the sea horizon. He then records the angle and does his calculations based on that angle. In the case of an artificial horizon sextant, the navigator would bring the sun into coincindence with a bubble or gyroscopic reference graticule which would be virtually identical to the sea horizon (I'm really simplifying things here - there's a bit more to it than that). I know from experience that the bubble horizon is very difficult to use at sea as the bubble dances madly about in the viewfinder with the least provocation.

I have a C.Plath marine sextant artificial horizon that was based on the SOLD design but in this case was intended to be fitted to the marine sextant in place of the telescope; again, this was all intended for use in submarines to give them a greater flexibility in position fixing. Given a stable platform, they are remarkably accurate, but trying to employ this on a pitching vessel will drive you nuts. Under some sea conditions, however, taking an accurate observation is "do-able".

Incidently, C.Plath marine sextants were used on U-boats. In fact C.Plath produced a distinctive pattern aluminum framed (as opposed to bronze) "U-Boat Sextant". I had a chance to get a hold of one some years ago, but regrettably, did not follow through.

Sorry for droning on. I'll stop now while everyone is still awake.


Robert Eno