found at the flea.  Used on a square nut  can't read the writing very well.

Possibly a bed key - used for tensioning the spring sub-base on old wooden framed beds...

I have seen the same (square nut t-handle design 6" long) used as a key to a lock on a side-box of an industrial truck bed.

 The Owsley Bros had a patent on the Acme twist handle wrench. Don't know if this wrench was made by same company.

Owsley Bros was indexex under wrenches, and 'general merchandise', so it's plausable at least.

The wrench may not be for anything in particular, square T-handle wrenches were a standard wrench type once upon a time, you just don't see them much these days...

I have seen wrenches like this used for turning valves on and off, such as gas valves on cylinders, etc.

looks like a tool to open groun level valve boxes like natural gal,water or gasoline   

I would be willing to say its a sillcock key.

Basicly used for opening and closing comerical pipe fittings.