Lever a place to stand, and I shall move the Earth with it' is a remark of Archimedes who formally stated the correct mathematical principle of levers (quoted by Pappus of Alexandria). It is assumed that in ancient Egypt, constructors used the lever to move and uplift obelisks weighing more than 100 tons. A lever is a beam connected to ground by a hinge, or pivot, called a fulcrum. The ideal lever does not dissipate or store energy, which means there is no friction in the hinge or bending in the beam. In this case, the power into the lever equals
Lever escapement symmetrically on the lever, making beat adjustment simpler. Watches that used these escapements were called "pin lever watches", and have been superseded by cheap quartz watches. One recent trend in escapement design is the use of new materials, many borrowed from the semiconductor fabrication industry. A problem with the lever escapement is friction. The escape wheel tooth slides along the face of the pallet, causing friction, so the pallets and teeth must be lubricated. The oil eventually thickens, causing inaccuracy, and requiring cleaning and reoiling of the movement about every 4 years. A solution is to make the escape wheel