(Source : http://www.google.co.in/#hl=en&output=search&sclient=psyab&q=Spiral+Staircase&oq=
Spiral+Staircase&gs_l=hp.12...217.870.0.2992.4.4.0.0.0.0.0.0..0.0...0.0...1c.qL8ha0mgbrg&pbx=1&
bav=on.2,or.r_gc.r_pw.r_qf.&fp=13f6aaee78637b17&biw=1328&bih=574 ; Aug 4, 2012)

A spiral stairs (plate 13) is actually helicoids shape, as well as variations on the screw auger. The Greek mathematician, astronomer and philosopher Archimedes (285-212 BC) is generally credited with the developing the Archimedes Screw (plate 12B), a device that is used to raising groundwater from the well. Traditionally the same technique is used for irrigation, extracting water from well or for tilling soil.

Plate 14A Archimedes’s Screw ‘Rural Well’, India (Helicoids)	14B Water well, Punjab	14C Harvest and Tilling

The Archimedes Screw is helicoids within a cylinder tilted at about 45-degree tilt. As the screw is turned, pockets in the form move steadily upward. The device (plate 14A&B) is widely used in the rural India for pumping water from the community well and in agriculture and also for tilling the soil (plate 14C). The advantage of the device is it is resistant to clogging. The same application is used for moving grain and controlling the flow of materials from hoppers.  Extracting water from lower heights (plate 15A) the Archimedes Screw is widely used in the agriculture sectors. It is one of the classical traditional techniques that are used around the world for centuries.

Plate 15A Archimedes Screw for drawing Groundwater		15B Dutch Windmill	15C Hydro Turbine