Spring use most of the information has a different degree of flexibility, if it twists and turns, with great power will restore its original shape. In human history, will have long noted that seedlings and saplings branches have great flexibility, since many civilizations initial use of this feature, in the cage after a special door or a stick on the wedge, perhaps with a slipknot set in a rod to drop down; once the tension is released, it will be the root of the stick or rod to rebound. They came to capture the birds and animals in this way. In fact, the bow that is in this way using saplings resilient spring; bow backwards first, then let go, let it rebound. The Middle Ages, the idea began to appear on the machine, such as textile machines, lathes, drilling machines, grinding machines and saws. The operator is given by hand or foot pedal under the pressure stroke, pull down the work machine, then use the rope fixed to a rod mechanical bounce occurs reciprocate

Torsion elastic material does not push to its flexural resistance. Empire Greece (probably 4th century BC) to create clarity with twisted rope or wool tendon hove tight torsion spring to replace the simple spring to strengthen the power of the catapult and trebuchet. Then we began to realize that the metal is greater than the elastic wood, horn, or any kind of organic matter. Philo (his writing about the era of 200 BC) put it as a new discovery to be introduced. He estimated audience was incredible. Celtic and sword resilient Spaniards, caught his attention Alexandria predecessors. In order to understand why flexible sword, they conducted many experiments. The outcome of his master Kete Xi Xi Trebuchet than create, spring trebuchet is made of twisted bronze plate - indeed the earliest leaf spring; Philo himself further improve these Trebuchet. Kete Xi endowed with creative than in the creation of this Trebuchet, he came up with another trebuchet - a job which occur when using an elastic inner cylinder of pressurized air.