French, C. 1860, signed in script J. Duboscq a Paris', consisting of a lacquered brass chamber with a hand turned large gear driving a pinion which in turn drives another gear which turns two internal shutters, at the top of the circular chamber is a small brass drawer into which is placed the mineral to be viewed. Note: This instrument, the phosphoroscope, was designed in 1857 by Edmond Becquerel, it enabled him to see the very short lived phosphorescence in minerals. It works by placing the mineral to be tested in the small brass holder and into the small opening near the gearing, as the mechanism turns the mineral is exposed to the light source through rear of the instrument. The sample is then viewed through the front aperture. By varying the speed of shutter rotation, the duration of the afterglow can be determined.