I became curious about these steel squares when I realized that there were several factories producing steel squares on Paran Creek, which runs from Shaftsbury, through N. Bennington to the Walloomsac River. Lots of factories because of lots of demand - one factory, swept away in a flood in 1852, was immediately rebuilt.
At the same time Asher Benjamin is publishing his pattern books.
And post and beam framing systems are evolving from scribe rule to square rule. This is a change from each tendon fitting only one mortise, to the parts being interchangeable. For example, a brace could fit between the post and beam (sill and stud in the illustration) at the front of a barn or at the back.
Do these facts have anything in common?
A joiner needs to know the angle he uses will be the same each time, dependable, before he can make the same part to be used many places. He needs to own a carpenter square even if it is expensive, and it was - at least a week's pay.
Does the manufacturer of many, many carpenter squares in Vermont a play a role in the evolution away from design using 'regulating lines'?
The Eagle Square sign comes from The Shires of Bennington, published by the Bennington Museum in 1975. The illustrations were drawn by Edwin Tunis for his book, Colonial Craftsmen, the World Publishing Company, 1965.