Spring gets smaller when compressed and get bigger when stretched. As the forced applied, the spring gets larger or smaller (or flattened or more tightly coiled). The most interesting aspect of the Spring Paradigm, as the spring is released; it releases mechanical energy and returns to its original size. It is the resistance to compression that causes the compressed spring (plate 20A) to return to its larger original form. The resistance to stretching that causes the stretched spring to snap back to its smaller form. In a stretched or compressed state, spring can store enormous energy making them good power source for the Windup Toys and Clocks. Commonly we are associated with compression spring (plate 20C), tension spring (plate 20D) and wave spring (plate 20B). In each case storing the energy and converting it at our advantage has given us numerous innovative design solutions. Using spring mechanism for toys and watches are common in our life.

Plate 21A Spring Toy	21B Spring loaded Car	21C Grandpa Pocket Watch	21D Wall Clock

(Source: http://www.google.co.in/search?hl=en&sclient=psy-ab&q=Spring+Toys&btnG=; Sept. 8, 2012
& http://www.google.co.in/search?hl=en&q=Spring%20products&bav=on.2,or.r_gc.r_pw.r_qf.&biw=
1332&bih=581&noj=1&um=1&ie=UTF8&tbm=isch&source=og&sa=N&tab=wi&ei=4UlLUMqfBofpr
AeN5YD4Ag ; Sept. 8, 2012)

The spring mechanism is built in every living being. Depending on the situation the spring mechanism is used. To jump above a wall or a stream of water one has to use the spring technique. It is like a flipper where the energy is stored for a specific period and then released to reach the target. Robert Hooke, FRS (18 July 1635 – 3 March 1703) was an English natural philosopher, architect and polymath who played an important role in the scientific revolution, through both experimental and theoretical work. Hooke is known principally for his law of elasticity (Hooke's Law) and for his work as "the father of microscopy" — it was Hooke who coined the term "cell" to describe the basic unit of life, but was for over two centuries after his death an obscure figure.