Thanks Bill, I have now found that vulcanizer in a Motor book (Hearst, 1910). I see now how this would be a good form for laying a hot vulcanized patch in a tire casing (were talking teen's tires here...skinny!!), and then placing the patched tire on the form.
The original mounting setup for this might come from the side, allowing the tire to "drape" the form, thus allowing the repairman to strap it down to the form with a belt or rope in between the form legs.
I've mounted this on a short board to quickly clamp in a vice for tube repair.
I'm calling this case closed! Nice!
J