UNIDENTIFIED FOCUSING MECHANISM
Manufacturer unknown Late 1930's - Early 1940's
Unmarked as to maker, this appears to be some type of focusing mechanism or calibration tool, that would have been used on a Bell & Howell 2709 or a Mitchell Standard motion picture camera.
The unit, which would mount in place of the camera's existing lens turret, is probably missing some linkage or other components. The only markings present are on the large gear, being "Boston" for presumably the Boston Gear Company and "G-269" which is either a casting number or a part number.
The unit is outfitted with a Cooke Speed Panchro 50mm f2 lens, Serial No. 255,300 which places the lens' manufacture to about 1939. The Speed Panchro, introduced in the 1920's, was a high-grade cinema lens used on professional motion picture cameras into the 1960's. The lens itself is not a definitive indicator as to the date of this device, which does look to be something reminiscent of the 1920's and 1930's.
A search of patents by John E. Leonard (Mitchell Camera), George A. Mitchell (Mitchell Camera) and Albert S. Howell (Bell & Howell) has yet to reveal anything that mirrors this particular device.
Certainly an interesting and unusual item that we'd like to learn more about.