Stagville Peg

This picture shows a broader overview of some of the joinery methods that go into timber framing. It appears evident from the reduction in the main pegged mortise and tenon joint in the center of the photo that the enslaved builders were using square rule method, an American method of timber framing that began around 1800 and goes on the idea that within every irregular timber is a perfectly square timber ready to be worked. For example, a nominal 7x7 post may actually measure 7 1/4 x 6 3/4. With square rule, though, instead of worrying about this irregularity, the builder can simply say the square timber inside is 6 1/2 x 6 1/2 and build based on those measurements.

This is a method that, as you can well imagine, involves a lot of math on top of the skill to actually do the building. It makes due with what the builder has at hand in order to still raise a frame that is square, plumb, and level, ready to withstand the test of time.