Archimedes' screw a crank mechanism in his "Bellifortis" (1405). This mechanism quickly replaced the ancient practice of working the pipe by treading. The Archimedes screw consists of a screw (a helical surface surrounding a central cylindrical shaft) inside a hollow pipe. The screw is usually turned by windmill, manual labor, cattle, or by modern means, such as a motor. As the shaft turns the bottom end scoops up a volume of water. This water is then pushed up the tube by the rotating helicoid until it pours out from the top of the tube. The contact surface between the screw and the
Acorn Archimedes share in the education markets of the UK, Ireland, Australia and New Zealand; the success of the Archimedes in British schools was due partly to its predecessor the BBC Micro and later to the Computers for Schools scheme organised by the Tesco supermarket chain in association with Acorn, and most students and pupils in these countries in the early 1990s were exposed to an Archimedes or A-series computer. The Archimedes range was available in the US and Canada via Olivetti Canada. By the mid to late 1990s the UK educational market began to turn away from the Archimedes. Apple Macintosh