Here's a bit more literature, closer to period correct, coming in from 1898.
From Iron Age v61 in 1898
The Germantown Tool Works.
These works were established in a small way in
1861 in historic Germantown, then a suburb of Philadelphia by
Selsor, Cook & Co, the plant being known for some time as the Keystone Tool Works. A miscellaneous character of goods was manufactured, prominent among them being Coffee Mills, Bridle Bits and Farriers' Tools. During the war of the rebellion some large contracts for Bridle Bits were undertaken for the Federal Government. In 1870, Mr. Cook retired, and the business was conducted by Mr. Selsor, without change in the name under which trading was carried on. In
1878 Mr. W.H. Sowers, a prominent Hardware jobber of the Philadelphia area, succeeded to the business, and the same was thereafter carried on
under its present name, Germantown Tool Works. Mr. Sowers associated with himself W.S. Skinner, another well-known Hardwareman. In 1887 Mr. Skinner died, and the business was continued by Mr. Sowers up to the time of his death in 1891, when it passed into the hands of the present proprietors, John R. Griffith and S.F. Wilson, well known in Hardware circles as the proprietors of the jobbing business carried on under the name of Shields & Bro. on Market street, Philadelphia. The product of the works now comprises a variety of Carpenter's Tools, and employment is furnished regularly for 50 men. Mr. Selsor, one of the founders, is still at the works, filling a responsible position, and it is worthy of remark that he has been at his post in the works almost every working day since the establishment of the plant 37 years ago.
So I see:
The start of "GTW" as 1878, and the end still open from this article.
Selsor, Cook & Co then goes 1861 to 1878 (DAT has 1865 to 1873) (possibly succeeded by George Selsor & Co from 1867 - 1909)
Keystone Tool Works ends in 1861, noted as Farriers' Tools
Dang, another rabbit hole just got 2 extra branches (and some other random findings)
From 1912 American Machinist Volume 36, Issues 1-13 1912
An ad from The Lather 1911
https://www.google.com/books/editio...YAAJ?hl=en&gbpv=0&bsq="Germantown tool works"
Here is some stuff possibly of interest to Lugz, POs by the army in 1918 ( (but a war early?)
And George Selsor assigned a patent to GTW,
US318312, a die for making hatchets, not in DATAMP (and closes a loop on whether George was the Selsor in & Cook in DAT.)
Lets see what also pops up, Street addresses
The Railroad, Telegraph and Steamship Builders' Directory 1888 (412 Commerce St)
Iron Age 1894 (518 Commerce Street)
The Railroad, Telegraph, Electric and Steamship Builders' Buyers' Guide and Directory 1897 (412 Commerce St)
The American Hardware Jobbers' Directory of the United States and Canada Volume 5 1918 (57 Armat S)
Rudder Marine Directory 1920 (521 Market St)
Industrial Directory of Pennsylvania Volume 3 1920 (520 Commerce St)
OK, gotta get back to the day job
