Significance: The Scotch Turbine (as well as another that can be found at Plane 9 West) is an early 19th century example of a reaction wheel. Precursor to the modern hydraulic turbine developed in the mid 19th century, the reaction wheel worked on a principal of reactive pressure, as opposed to the direct pressure exerted on a water wheel, and worked much the same way a lawn sprinkler does. Although not very efficient it has the ability to run submerged and does not require the room that a water wheel required. Its use of iron casting in fabrication helped bring water power into the iron age.