Impulse Balance
   The 1950 Central Scientific Company catalogue has rather an extensive history of this apparatus, which is designed to show the relationship between the force exerted by a stream of water and its rate of flow.

   The original suggestion was made by Reichel in 1891, and it was repeated by Coleman, writing in School Science and Mathematics in 1912.

   A jet of water of known ` area strikes a plate on the end of the pendulum that is pivoted at the top of the apparatus. A weight hung from the horizontal beam supplies a torque that balances the torque exerted by the stream of water. The spent water is collected for a known period of time, and the momentum delivered per unit time can be calculated and compared to the force needed to balance the system.

   The apparatus is at Kenyon College. In 1940 it cost $22; by 1950 the cost had risen to $60.