(Source:http://www.google.co.in/search?um=1&hl=en&tbm=isch&q=old+bow+and+arrows&revid=
341498604&sa=X&ei=xr9EUMClCNDyrQfEhYCIAQ&ved=0CEUQgxY&bav=on.2,or.r_gc.r_pw.r_qf.
&biw=1341&bih=581&ech=1&psi=xr9EUMClCNDyrQfEhYCIAQ.1346682828984.3&emsg=NCSR&
noj=1&ei=xr9EUMClCNDyrQfEhYCIAQ ; Sept. 4, 2012)

A spring is an essential mechanism that is widely used for storing energy. Spring stores mechanical energy and releases it through expansion (bigger) mechanism. From ancient time we have used spring like ornamental motifs (plate 19) replicating the effect of spring. Springs are usually made out of hardened steel. Small spring can be wound from pre-hardened stock, while larger one made from annealed steel or tempered steel (bring to a desired consistency, texture, or hardness by a process of gradually heating and cooling) to bring to a desired consistency, texture, or hardness by a process of gradually heating and cooling.