I found an old standard rule square that I read about here on someone's post. I also read somewhere that they are pretty rare and that "all known examples have either the patent number , or just the patent date".

This one says "patent applied for" on it. Does anybody know if this could be even older???

I also should mention that I believe it to be a bookkeeper square from what I have read. Any information would be greatly appreciated. 

Thanks

Paul, do you have a picture of the square?

A picture would help. Plus I would love to see it.

Images of Paul's square-