Galoots

Whilst we were at the Tools Of The Trade sale on Sunday, Dan
acquired a strange chisel.  He almost passed it by, except that
the tip of the chisel caught his gaze.  There was something odd
about it.

At first glance it was a bog standard sash mortise socket chisel.
Missing the handle, of course.  But other than that it was in fine
shape.  No hamfisted idiots had beaten on the socket, no pitting
and it was reasonably shiny and overall in great shape.

But the back of the chisel was hollowed out along its length.
And it is very well done, so well done in fact that we all think it
was manufactured this way.  By none other than P. S. & W.

Looks kinda ordinary right?
http://galootcentral.com/components/cpgalbums/userpics/10074/IMG_201704
02_121015.jpg">http://galootcentral.com/components/cpgalbums/userpics/10074/IMG_
20170402_121015.jpg

Why is the back of the chisel hollow?
http://galootcentral.com/components/cpgalbums/userpics/10074/IMG_201704
02_120945.jpg">http://galootcentral.com/components/cpgalbums/userpics/10074/IMG_
20170402_120945.jpg

So, what is this thing?
An incannel sash mortising gouge??
What would it be used for?

-- 
Darrell LaRue
Oakville ON
Wood Hoarder, Blade Sharpener, and Occasional Tool User