Early Water Power
The source of power for these mills was the waterwheel. At the Gilbert Stuart Birthplace, an undershot wheel powers the snuff mill and a breastwheel powers the gristmill. Each wheel is connected to the river by a channel of water called a raceway. The portion of the raceway above the wheel is called the headrace; the portion that returns the water to the river is called the tailrace.
The vertical distance between the headrace and the tailrace is known as the head. The amount of power available at any site depends on the head and the rate of flow. A gate at the beginning of the headrace regulates the rate of flow. Dams were often built increase the amount of head at the mill site. The millpond often created by these dams also helped to provide a steady supply of water for the wheel.
Power from the waterwheel was transferred to the machines through a series of gears and shafts called the power train. In the case of the snuff mill, two gears turn a lantern pinion that provides power to the snuff-grinding machine. By going from larger to smaller gears, the snuff grinder can be turned much faster than the waterwheel itself. This simple system could easily be expanded to power many machines from a single waterwheel.
The importance of waterpower increased dramatically in 1793 when Samuel Slater built the country's first successful water powered textile mill on the Blackstone River in Pawtucket, Rhode Island. Slater's success formed the basis for a new economy in New England - one much more lucrative than grinding grain or sawing logs. Small gristmills and sawmills throughout New England were replaced with water-powered textile mills. The first textile mill in Woonsocket, the Social Manufacturing Company, began on the Mill River in 1810. By the mid-nineteenth century, Woonsocket had grown to become one of the largest textile manufacturing centers in the United States.
Waterpower remained important to the Woonsocket economy until the end of the 19th century when it was eventually phased out, replaced by power from steam boilers and electric generators. As the use of waterpower declined, so did Woonsocket's industrial base - especially the textile industry. As long as Woonsocket mills could obtain free energy from the river, they had a competitive advantage. When technology made the use of waterpower unimportant to the energy needs of manufactures, the mills moved south where labor and electricity were less expensive.