the apparatus rotates a drum that has a window slot containing a glass insert, possibly for gauging rotational speed of a shaft viewed through the window or light projected through the window; hand or belt driven
on a triangular wooden base with three adjustable feet. Two vertical wooden circular frames separated by four brass rods, hold wire coils connected to four brass terminals. In the middle a turned wood pedestal holds a horizontal circular scale of…
Bakelite case containing metal bubble sextant mk 9A; model no 12560/43; serial no 9054/42; patent nos 480112, 490621; case has two metal hinges; power cord has two small prongs on plug and battery on other end