I finally got one of these today.  Who made it?

I don't know who made but somebody took good care of it   bob w.

Stanley rule and level, oddly...

Sure doesn't look like a wood plane...; P

Thanks guys for the compliments and for providing this wrench's provenance!

Datamp advise that the Triplet Wrench was made by The G. L. Holt Company of Hartford, CT.

It is possible I suppose.

Strange for Stanley to have resold it instead of making it, but, odder things have happened...

Oui, c'est possible mon ami! D'accord.

Cope's book (page 170) also credits the G. I. Holt Co. of Hartford, Conn. as manufacturer. I recall reading that Stanley sold them for a while, can't remember how long but not very long.

John Walter's Stanley Tools book states they are circa 1913. It also states that it was never listed in any catalog. 2 versions one marked Triplet and one marked with the patent date. 1996/1997 Walter's books valued them at $100-$250. I got mine for $10 a few years ago at a flea market. Patented 8/19/1913 John Anderson

What flea market provided you with a $10 Triplet?

And Bus, I rechecked the DATAMP site, and Gardiner Holt's middle initial was L.  It's written in such a skinny font that it looks like an I.

Your right the middle initial is "L" not "I".

I searched through past auctions and came up with three variants of the Triplet Wrench:

TRIPLET WRENCH PAT APPLIED FOR

THE TRIPLET PAT AUG 19, 1913

and an unmarked example that is, thicker, heavier, and with no notches for the tap wrenches

Well if I told you what flea market I get my deals at then everybody would know, it is to far north in PA for you Wrenchmensch.

So, an IM would do.