I had to buy this "thingey" when browsing through a machinery dealer's offerings a few weeks ago. The price marked on the sticker was $5!
I knew exactly what it's new purpose will be the moment I saw it and I'll show progress on the project when I finalize the sketches/drawings.
The rest of the photos show different views of the gadget.
It has an angle adjustment using the graduated wheel on top giving a resolution of 0.01 degrees. and can move from -10 degrees to +90. The 360 degree plate is adjusted by the cogged wheel and can be disengaged by the little copper lever. The last photo (of the underside) shows an adjuster for lining up the jig?
I wonder if the collective wisdom of this group can give me an idea of its original purpose. The horizontal turntable has a cogged wheel attached to the adjuster and, if you look closely, the vertical adjuster has a threaded hole in the top. The whole unit is very well made with an adjustable gib strip and ball bearings on all shafts.