before to the invention of the sawmill, boards were sawn by two men with a whipsaw, using saddleblocks to hold the log, and a pit for the pitman who worked below. sawing was slow, and required strong and enduring men. the topsawer had to be the stronger of the two because the saw was pulled in turn by each man, and the lower had the advantage of gravity. the topsawyer also had to guide the saw so that the board was of even thickness. this was often done by following a chalkline.