Billygoat,
You have a real rarity there......
The Parker Co., along with pretty much every other 'main line' manufacturer of machinists' vises, offered a few sizes of 'combination bench and pipe vise'.
The generality of that type of vise looks much the same as yours, except for the height of the jaw, and the pipe grip capacity. Your vise has seems to have a bit larger pipe capacity than was usually standard for a 'combination' vise.
Do yourself a favour, and use that vise very gently, if you use it at all. Yours is the only one I've ever seen which hasn't been broken and sent to the scrap yard, or broken and repaired by welding or brazing, and still in use. That high jaw is very delicate, when you consider the leverage it has on the beam area of the movable jaw.
(if that vise were mine, I'd do a restoration to original appearance, or as nearly so as could be done, and consider it a 'display piece' for a steam-related museum or similar situation. Its too rare (in an unbroken/unrepaired state) as a museum piece to consider a 'using tool', actually......I'd not be surprised that you could very easily trade it for a later version (late '30's to early '50's production was generally the 'high water mark' of quality in vises, and the 'Reed' or 'Athol' makes are to be preferred over the 'Parker' in terms of strength, from what I've seen) best quality machinists or combination vise, one in excellent condition, which would be much more practical/convenient to use.
cheers
Carla