To lay out lines for hewing, the timber’s cross-sectional dimensions were drawn onto both ends of the log, with their sides established plumb. The Americans typically used spirit levels to do this, but some of the French carpenters used plumb bobs to establish these lines. Once the ends were drawn, they were connected down the length of the log with the snap of a chalk line, making a straight timber from the natural, irregular tree. In most cases, the carpenters peeled a strip of bark only where the lines would be snapped, rather than peeling the entire log. This served two purposes: First, it saved labor because peeling bark in areas that were going to be hewn away would be wasted energy; and second, the bark provided grip for standing on when working the log underfoot. Freshly peeled logs are slippery.
The lines were snapped carefully. Although the subtleties of using a chalk line are something I never really thought too much about, when snapping lines on irregular pieces (such as logs), it is critically important to lift the string exactly plumb so that it is in plane with the sides of the timber, otherwise the line will snap out of plane in low spots. To ensure that the taut line was plumb before letting it go, another carpenter would sight the line for them. “No, a little to the left. A little back. There.” Snap! This way, a dead-straight line could be achieved no matter the topography down the length of the tree. In addition to a trained eye, squares and levels were sometimes used to ensure that the line was plumb before snapping.
–Joshua A. Klein, excerpt from “Showing Us What is Possible: A New Vision of Work from Charpentiers sans Frontières,” in Issue Eight