What is the power?
The force that opens or shuts the door is the power.
What other examples of this kind of lever have we?
We have an example in the lid of the tea-kettle, and in the cover of the ink-stand, when they are fastened on by hinges.
What is the third kind of lever?
It is where the power is between the fulcrum and the weight, as is shown in [Fig. 48].
Fig. 48.
What examples of this kind of lever have we in common use?
The shovel, the spade, and the pitch-fork, are levers of this kind.