One tube regenerative radio
I believe this little breadboard radio to be a kit. The knob on the little variometer and that on the variable cap are of the same style. I have seen similar kit sets in the Allied catalogs of the late 1930s. The tube is a type 31. When I first located this, all of the components including pencil-marked Fahnestock clips were mounted on the plywood board with small wood screws and were ready to be wired. No wiring or solder had ever been applied. I had to repair the variometer as the Double Cotton Cover insulation on the wires of the movable coil had deteriorated. I wired the set with DCC wire according to the generic diagram shown and was able to make it work surprisingly well with a pair of "D" cells for the "A" supply and 5 rather worn 9 volt batteries in series for the "B" supply. Assuming this was indeed a kit, let me know if you can identify the distributor.
I have been told this kit was part of an early NRI (National Radio Institute) course. If you have evidence in the form of a diagram or printed material, please let me know.