Lever

Lore & Background

The word 'lever' entered English around 1300 from Old French 'levier', stemming from the verb 'lever' meaning 'to raise', which goes back to Latin 'levare' and the adjective 'levis' meaning 'light'. Its primary origin is the Proto-Indo-European stem 'legwh-', meaning 'light', 'easy', or 'nimble', which also gave rise to the English word 'light' as the antonym of 'heavy'.

Autumn Stanley argues that the digging stick can be considered the first lever, positioning prehistoric women as the inventors of lever technology. The next earliest known cultural evidence of the lever mechanism dates back to ancient Egypt c. 5000 BC, used in a simple balance scale. In ancient Egypt c. 4400 BC, a foot pedal was used for the earliest horizontal frame loom. In Mesopotamia c. 3000 BC, the shadouf, a crane-like device using a lever mechanism, was invented. In ancient Egypt, workmen used the lever to move and uplift obelisks weighing more than 100 tons.

The earliest remaining writings regarding levers date from the third century BC and were provided, by common belief, by the Greek mathematician Archimedes, who famously stated 'Give me a lever (long enough and a fulcrum on which to place it), and I shall move the world.' The Greek usually attributed to Archimedes does not include details about length of lever or fulcrum. That statement has given rise to the phrase 'an Archimedean lever' being adopted for use in many instances, including abstract concepts.

Reader's Guide

The lever is a fundamental simple machine that has been used since prehistory, with evidence of its application in ancient Egypt and Mesopotamia. Its significance lies in its ability to provide mechanical advantage, trading off force against movement. The law of the lever, expressed mathematically, shows that the mechanical advantage equals the ratio of the distances from the fulcrum to the points of application of input and output forces. This principle allows a smaller input force to move a larger load when the input distance is greater than the output distance.

Levers are classified into three types based on the relative positions of fulcrum, effort, and resistance. Class I levers have the fulcrum between effort and resistance, allowing mechanical advantage that may be greater than, less than, or equal to 1. Class II levers have the resistance between effort and fulcrum, always providing a mechanical advantage greater than 1, making them force multipliers. Class III levers have the effort between resistance and fulcrum, always providing a mechanical advantage less than 1, making them speed multipliers.

The lever's legacy extends beyond mechanics into abstract concepts, as the phrase 'Archimedean lever' is used metaphorically to describe actions that achieve results that could not have occurred without them. Compound levers, comprising several levers acting in series, are found in scales, nail clippers, piano keys, and even the middle ear bones (malleus, incus, stapes) that transfer sound waves.

Did You Know?

• The word 'lever' entered English around 1300 from Old French 'levier', meaning 'to raise'.
• Autumn Stanley argues that the digging stick can be considered the first lever, positioning prehistoric women as inventors of lever technology.
• The earliest remaining writings regarding levers date from the third century BC and are attributed to Archimedes.
• The malleus, incus, and stapes in the middle ear are connected as compound levers that transfer sound waves.