This is a rather unique and unusual saw, and it also has some unusual claims. I wish I could tell you that I've put it to the test, but I haven't, and probably won't. This example appears to be unused and I don't want to change that. The teeth are very sharp as is the tip. The blade has a very shallow hollow grind, probably to make it easier to drive and withdraw. I don't know what kind of steel this would have been made from but it must have been extremely tough.
What follows is from an advertisement that appears to have been put out by the manufacturer, one Lewis E. Williams of West Groton, Mass.
Shepley's Patent
Double-Edged
Drive Saw
for
Plumbers and Carpenters' Use, or for any occasion
where Holes are to be Bored
__________________
No. 1 cut shows the Saw and Handle in a straight condition,
While no. 2 shows the position for use. By shifting a slide on the
handle puts it into position for driving, as seen in cut No. 2. After
having driven through your board or plank, take a claw hammer and
withdraw it. The hole having been made you can proceed to saw any
way you may desire.
This saw is peculiarly adapted for Plumbers and Carpenters' use
and can be used where a common brace and bit cannot. It is made of
the best steel and can be driven through a two-inch board, either way
of the grain, if necessary, without breaking.
This unusual saw was patented by Granville T. Shepley on Feb. 19, 1889; pat. no. 398,350
Datamp link below.
http://www.datamp.org/patents/displayPatent.php?number=398350&typeCode=0
Mike