Daily Archives: January 22, 2016
iPhoneOgraphy – 22 Jan 2016 (Day 22/366)
The screw was one of the last of the simple machines to be invented. It first appeared in Ancient Greece, and by the first century BC was used in the form of the screw press and the Archimedes’ screw, but when it was invented is unknown. Greek philosopher Archytas of Tarrentum (428 – 347 BC) was said by the Greeks to have invented the screw. The Greek philosopher Archimedes is credited with inventing the Archimedes’ screw water pump around 234 BC, although there is evidence it may have come from Egypt. Archimedes was first to study the screw as a machine, so he is sometimes considered the inventor of the screw.
Greek philosophers defined the screw as one of the simple machines and could calculate its (ideal) mechanical advantage. For example, Heron of Alexandria (52 AD) listed the screw as one of the five mechanisms that could “set a load in motion”, defined it as an inclined plane wrapped around a cylinder, and described its fabrication and uses, including describing a tap for cutting female screw threads.
Because they had to be laboriously cut by hand, screws were only used as linkages in a few machines in the ancient world. Screw fasteners only began to be used in the 15th century in clocks, after screw-cutting lathes were developed. The screw was also apparently applied to drilling and moving materials (besides water) around this time, when images of augers and drills began to appear in European paintings.
The complete dynamic theory of simple machines, including the screw, was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche (“On Mechanics”).