seven segment display history

[Brent Hilpert]

Ethan Dicks wrote:
> 
> I have something like that with me here in my bag-o-parts... approx 20mm
> by 30mm, with a 2mm-thick body made of a rough, dark ceramic, with a 1mm
> thick glass top.  It's a 2.5 digit display with + and -.  All the leads
> come through the back of the package in what appears to be a straight-
> through fashion (making it easy to figure out how to hook it up).
> 
> There is a vendor and part number etched on the face: Sperry SP-738.
> 
> I've never tried to hook it up to anything, and have no idea what
> voltages it might want.  It's a shame it's only 2.5 digits; if it
> were 3.5 digits, it might make an interesting 12-hour clock face.
> Not sure what I'd need to do that swings from -199 to +199 off the
> top of my head.

Temperature?

Your description sounds like the Sperry/Beckman gas-discharge displays, e.g.:
  http://www.tube-tester.com/sites/nixie/trade08-panaplex.htm
I think your part number is in there.
Can be cascaded with more digits, or a lot of early DVMs were only 2.5 digits.