The Mercury Ultra-Mike vacuum tube microphone

Our friend Donald wonders if anyone knows about this microphone. He says, “It is my first mike of this age and I would like to know more info on it but I can find nothing on the web. Any ideas where to get year and use information?” You are welcome leave your comments. Please specify “Ultra-Mike” in your message.

The following images were provided via the courtesy of Mr. Ralph Russell, who writes: This mic has provisions for two batteries, I am guessing a “D” cell in the front for filament voltage and a “B” battery in the back of the chassis. My set currently has a 6AL5 tube installed, but the chassis has 1L4 written in pencil.