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 action Lever-action designs with strong, rotary locking bolts (such as the Browning BLR with seven locking lugs) safely use very high-powered cartridges like the 300 Winchester mag, 300 WSM and 7 MM Remington magnum. Tilting block designs such as the Savage Model 99 are also strong enough to handle high pressures. Many lever actions have a tubular magazine under the barrel. To operate safely, cartridges for these have bullets with rounded tips, and some use rim-fire primers rather than center-fire primers. The safety problem is that long-range aerodynamic supersonic bullets are pointed. In a tubular magazine the points can accidentally fire