Silvertone.
Silvertone was the Sears brand (Airline was the MW brand). I don't know what company made your radio, but it looks like a VERY nice one in its day (dare I say TOL?). I'll bet the knobs are power/volume, tone, tuning, and band (AM/broadcast, and shortwave. I have no idea what knob #5 does. The tuning eye is a really nice feature, certainly not found on the cheaper sets. I would be quite confident in saying it's a pre-war radio.
Post the model number and I'll try to find it in my radio book. The model number should be either on the back or the bottom. In the likely instance that your radio never had a back (at that time they often didn't), look inside the cabinet for a model tag.
Hook up some copper wire for an antenna, ground the set, and wait until nightfall and see what far off stations you can tune in.
I have about 30 radios myself, and one of these days I need to get or build a very low-powered AM transmitter so I can play my ipod and listen to music throughout my house on my radios.
Nice set,
Dave