The main type is the circular saw which comes in a couple of types; 1. * For ripping timber or log into planks down the length, or 2. * cross cut saw which is often used to cut logs or timber up for fire wood and cuts across the log to create short lengths, which were then split by hand axe (originally) or by a hydraulic splitter (today). Early saws were belt driven by Steam engines or by a water wheel in a fixed saw mill. by the early 20th century Internal combustion engines were being used instead or tractors to provide the power.