Highfield lever Highfield lever A Highfield lever is a lever device which allows tension to be rapidly set up in a wire and equally rapidly released to the required extent. It is frequently used in sailing boats where tension in some part of the rigging needs to be adjusted to a pre-set amount as the wind impinges on one side of the sails or the other. It is typically used in running backstays (runners). To make it work, the backstay is led through a block or fairlead along the deck to a two-legged, second order lever mounted with its fulcrum above deck
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