A Legacy of Waterpower in Maine
Water was one of the most vital sources of power in the 1800s. Across Maine, nearly 2,000 water-powered sites helped drive local industry, from gristmills to sawmills. Towns were often built near rivers and falls specifically to harness this energy. In 1868 alone, seven water-powered mills operated on Blackman Stream. The current reconstructed Leonard’s Mill, built in the 1980s, honors this legacy by showing visitors how these technologies once worked.
The Flow of Power
A stone dam built at a natural falls roughly 200 feet upstream impounds water. Some of that water is diverted through a man-made canal into a mill pond beside the sawmill. Logs are stored here to prevent insect damage and to keep them conditioned for cutting.
From the mill pond, water flows down a wooden sluiceway to the top of a 9-foot diameter overshot waterwheel. The sawyer opens a wooden gate to control this flow. As water fills the wheel’s buckets, gravity turns the wheel—converting potential energy into mechanical motion.
The wheel turns at about 10 revolutions per minute and can generate approximately 3 horsepower, the equivalent of 30 laborers. Its large torque—1,600 pound-feet—makes it ideal for heavy work like sawing logs.
Transmitting Power
The rotating wheel drives a shaft connected to a large wooden bull gear with 58 teeth. This gear engages with a smaller trundle gear with 16 teeth, increasing the speed of rotation to 36 rpm. This gearing system powers a crank and connecting rod, which moves the saw sash up and down with a 2-foot stroke—36 strokes per minute.
The saw blade is mounted in a wooden sash that only cuts on the downstroke. A counterweight offsets the sash's weight to improve efficiency.
Loading the Logs
Logs are hauled into the mill using a block and tackle system mounted on a brow (a ramp leading into the mill). With a mechanical advantage of 4:1, the sawyer pulls 120 feet of rope to move the log 30 feet into place.
Once inside, the log is secured to a carriage that rolls on tracks. A rack and pinion mechanism, driven by a rag wheel, moves the log incrementally toward the blade.
Automatic Feed & Cutting
Each time the saw sash moves up, a pusher ratchet advances the rag wheel 6 degrees, feeding the log ¼ inch closer to the blade. A keeper ratchet locks the log in place during the downstroke. The entire mechanism is driven by wooden linkages connected to the sash.
Slicing through a 12-foot log takes about 15 minutes. At the end of the cut, a lever disengages the ratchet system. The sawyer then pulls a rope wrapped around a friction capstan (also water-powered) to rapidly return the carriage to its starting position. Releasing the rope halts the movement.
Production & Evolution
A water-powered sash saw like this could cut 1,000 board feet of lumber per day, a vast improvement over hand-powered pit saws. The museum has a working pit saw nearby for comparison.
Eventually, sash saws gave way to rotary and band saws, which offered continuous cutting action and faster output.
Waterpower Today
Though its applications have evolved, waterpower remains relevant. Today, hydroelectric turbines generate nearly one-third of Maine’s electricity—proof of the enduring value of this renewable resource.