Hi, this is a design I had not seen before. Many were made for school sports teams. The shape of the glass envelope is called H for hurricane (like an old "hurricane" oil lantern shade). It's most likely got a neon fill and, if it works, will glow orange. It might have argon and glow violet, but this is unlikely.
There is no need to bring it up slowly on a rheostat or Variac. It will either light or it won't (no inbetween) and it needs about 60 to 80 volts to "fire."
You can see some similar bulbs in the galleries, under Discharge and Neon.
Collectors (of which I am one) will pay well for a scarce one. Recently there was one for the University of Texas Longhorns (Hook 'em Horns) on eBay with a buy-it-now price of $99 (it might still be there). This is after a couple of us found some of that design for $15. But if you listed yours it might go for considerably more, into the low three figures. Nice find!