I have what looks like a sextant made by Charles Escher (the weird artist).
It has two scopes looking in opposite directions, both with variable density sun shields. The central mirror can be controlled from either side.
My first impression was that it was made to shoot Lunars or just to measure the angle between two objects. But that can be done with only ONE scope.
The odd thing is that both scopes use the SAME central mirror but it can be controlled by either side so independent measurements are not possible. Just one at a time.
My next guess is that is is an incorrectly interpreted copy of an old instrument that actualy allowed two separate measurements to be made at the same time.
So what is this instrument and how is it used. Any one REALLY know?