"Give me a lever long enough and a fulcrum on which to place if and I shall move the world"
Archimedes, mathematician and physician
The lever was first described in 260 B.C.E. by Archimedes (c. 287-212 B.C.E.), but probably came into play in prehistoric times. A lever can be used to raise a weight or overcome resistance. It consists of a bar, pivoted at a fixed point known as the fulcrum. Extra power can be gained for the same effort if the position of the fulcrum is changed.
Levers may be divided into classes. First-class levers have the fulcrum in between the applied force and load, which are at opposite ends, such as with the seesaw. Second-class levers have the fulcrum at one end, and the applied force at the other, such as with a bottle opener. Finally, third-class levers have the effort in between the fulcrum and the load; for example, tweezers have two class three levers that are pressed together to do the work for which they are designed.
The Egyptians used a lever in 5000 B.C.E. for weighing, pivoting a bar at its center to balance weights and the objects to be weighed. Ramps and levers were also used to move stones higher up a structure, adapting the principle of the shaduf, which was developed in Egypt in 1500 B.C.E. This machine had a lever pivoted near one end with a water container hanging from the short arm and counterweights attached to the long arm. Several times a person's weight could be lifted by pulling down the long arm.
