Mystery adjustable

[OldGitCentral]

Could anyone help me identify this one please ? 
It's 10 1/4" long.
I'm in the UK, but it could well be imported.
There are some markings in the casting, but I'm struggling to make them out.
On one side, my best guess is "PAT J&W ?? 1878" and on the other, "JAN 9.1877" but it could be almost anything. 
Thanks very much
 

[Lewill2]

I replied to your FB post. O. B. North Manufacturing Company New Haven Conn.

[OldGitCentral]

Thank you very much. The picture is perfect.  I wonder how long this design was manufactured.