On Thu, 24 Dec 1998 09:49:01 -0500 "Ed O'Riordan"

>One of
>them in particular intrigues me.  It has teeth cut on both sides of
>the blade... (the teeth are only cut about 1/2 the
>length of the back).  OK here are the particulars
>
>Blade length is 20", the regular teeth are about 9 TPI, the teeth on
>the back extend 10 3/8" and are 16 TPI. ...
>
I think it is possible that this is a floor saw, or a saw based on a
similar principle.
That is, the saw may be intended for starting a cut in the middle of a
panel, rather than cutting in from the edge.  Is the nose of the saw
rounded on the top, curving down to meet the flat underside?

That is how my floor saw is made, the teeth wrap around the tip and come
back about halfway along the back of the saw.  But on mine, the handle is
held on with a single
wing nut so it can be easily reversed.  The idea is that if you need to
cut a hole in a floor you can start the hole with the teeth on the
rounded tip and then reverse the saw back to the normal orientation after
you have cut through.

Alternatively, the smaller teeth on top of your blade might be 'starter
teeth' the idea here is to start a cut with the fine teeth and once a
kerf is established, turn the saw
over to finish.