Maker: Bell & Howell
Designed by: Albert S. Howell
Design Patent #: D 81,981
Measure type: Comparometer
Battery type: one C cell
Bell & Howell made movie cameras. Their earliest line was the 16mm Filmo from the mid 1920s. They had a great advertising campaign in old National Geographic magazines where they showed people using Filmos all over the world. So they were tied to adventure and travel and exotic locales.
I finally found an avertisement in an old magazine called Movie Makers from 1931. There were two versions, a "Model A" for movie work and a "Model B" for still cameras. I'm pretty sure I have a Model A but I'll have to find it and look again. Click on ad to the right and they explain the difference.
This is a smaller, earlier version of the SEI Photometer, but the principles are the same. The're a lamp inside, so what you do is look through the eyepiece (the bell end at the top) at whatever you want to measure, hold the button on the side, and twist the bottom of the handle to vary the intensity of the bulb inside. When the light from the bulb balances with whatever you're looking at, you can calculate the exposure.
Exactly how the calculation is done--I haven't figured out yet. The top band has the frame rate and the middle band has the aperture scale. The bottom has graduation marks but I haven't quite figured how it all matches up. That and the bulb is burned out and needs to be replaced, so I haven't been able to test it.