early sawmills simply adapted the whipsaw to mechanical power, generally driven by a water wheel to speed up the process. the circular motion of the wheel was changed to back-and-forth motion of the saw blade by a connecting rod known as a "pitman" (thus introducing a term used in many mechanical applications). a pitman is similar to a crankshaft, but in reverse; a crankshaft converts back-and-forth motion to circular motion.