| A | B |
|---|
| flow | The volume (amount) of water. |
| head | The height of the fall of the water. |
| efficiency | The measure of how well a waterwheel captures the weight (from the flow) and force (from the head) of the water. |
| crib dam | This dam an interlocking framework of timbers filled with stones. This was the earliest and simplest type of dam. |
| modern hydroelectric turbine | The turbine is a carefully engineered and highly efficient means of harnessing water power - very little power is wasted. |
| overshot wheel | More efficient wheel, but difficult to build. |
| breast wheel | a combination of overshot and undershot wheels. |
| tub wheels | This wheel is just a small undershot wheel mounted horizontally on a vertical axle. |
| outward-flow reaction wheel | is made of a hollow iron disk with a large hole on one side to allow pressurized water in from a penstock,and six angled holes on the rim to allow water to exit. The force of water squirting through these six angled jets causes the wheel to turn in reaction to the force of the exiting water. |
| undershot wheel | Are the oldest type of waterwheels and are not very efficient |
