A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Michael Bradley
Date: 2017 Aug 14, 16:25 -0700
Hello again Carl
My mind was wandering, late at night, my apologies: no electric motor is apparent on your instrument, but there is the eddy current brake acting as a light load or oscillation damper.
So it measures a wide range of voltage - an early muliti range volt meter is a possibility, but my original guess of the display for an electrical shaft speed measuring system still stands.
The complicated multi sectioned shaft running through the centre of your machine looks very much like a high quality switch - possibly for range changing by selecting different multiplier resistances.
And in a wooden panel - nice.