Where's Mr Truax? He is pretty knowledgable about this.

One interesting theory he told me about is that the War of 1812 may have been the vehicle for the square rule's rapid dissemination. Carpenters from all the states intermingling and traveling and learning new techniques, etc.

As for the earliest known example, 1801 sounds about right to me.

I, too, am interested in the circumstances surrounding this practically overnight change in carpentry that happened on this contintent.

One thing I am curious about is this -- Since the square rule was the norm in Canada (as Mark has said) where the cultural exchange with the UK was greater in the 19th century, why didn't it make it's way back to the UK as a viable method? I can understand it not spreading from the States to the UK in that time period, given our being at odds with each other. Any thoughts?

Gabel