This is the apparatus to find the equivalence between heat and mechanical energy. When the weights go down, the paddles in a water tank rotate to stir the water. The potential energy against gravity of the weights is converted into the kinetic energy of the rotation of the impeller, and the temperature of the water rises.
the temperature of the water rises. The paddle was sized to have a large resistance in the can of water, so that the weights on either side descended at the slow rate.
