Compound lever sudden movement of the key. The earliest remaining writings regarding levers date from the 3rd century BC and were provided by Archimedes. ""Give me a place to stand, and I shall move the earth with a lever"" is a remark attributed to Archimedes, who formally stated the correct mathematical principle of levers (quoted by Pappus of Alexandria). The idea of the compound lever is attributed to the Birmingham inventor John Wyatt in 1743, when he designed a weighing machine that used four compound levers to transfer a load from a weighing platform to a central lever from which the weight
Lever tumbler lock move. Typically, the belly of the lever is cut away to various depths to provide different combinations, or the gate is cut in a different location, to provide differs. A lever will have "pockets" (or "gates") through which the bolt "stump" (or "post" or "fence") moves during unlocking. There has not always been universal agreement about which variants of the basic design merit the terms "lever lock" or "detainer lock" or both. Some authors use the term "detainer lock" to refer specifically to variants where the gates are "open" (i.e. at the edge of the lever), rather than "closed" (i.e.