![]() ![]() ![]() The wooden cogs are held in place by nails. Ī cast gearwheel (above) meshing with a cogged mortise wheel (below). 1300 in the sense of 'a wheel having teeth or cogs late 14c., 'tooth on a wheel' cog-wheel, early 15c. From Middle English cogge, from Old Norse (compare Norwegian kugg ('cog'), Swedish kugg, kugge ('cog, tooth')), from Proto-Germanic * kuggō (compare Dutch kogge (' cogboat'), German Kock), from Proto-Indo-European * gugā ('hump, ball') (compare Lithuanian gugà ('pommel, hump, hill'), from PIE * gēw- ('to bend, arch'). In this context, the meaning of 'toothed wheel in machinery' first attested 1520s specific mechanical sense of 'parts by which a motor communicates motion' is from 1814 specifically of a vehicle (bicycle, automobile, etc.) by 1888. The word gear is probably from Old Norse gørvi (plural gørvar) 'apparel, gear,' related to gøra, gørva 'to make, construct, build set in order, prepare,' a common verb in Old Norse, "used in a wide range of situations from writing a book to dressing meat". Wooden cogwheel driving a lantern pinion or cage gear In nature: in the hind legs of the nymphs of the planthopper insect Issus coleoptratus.200–265 AD: Ma Jun used gears as part of a south-pointing chariot. It could predict the movement and position of the sun, moon and planets decades in advance and could solve different astronomical problems. 2nd century BC: The Antikythera mechanism, the world's oldest analog computer is built.725 AD: The first geared mechanical clocks were built in China.6th century AD: A geared calendrical device showing the phase of the Moon, the day of the month and the Zodiac was invented in the Byzantine empire. 1221 AD The geared astrolabe was built in Isfahan showing the position of the moon in the zodiac and its phase, and the number of days since new moon. 13th–14th centuries: The worm gear was invented as part of a roller cotton gin in the Indian subcontinent. The Astrarium had seven faces and 107 moving parts it showed the positions of the sun, the moon and the five planets then known, as well as religious feast days. ![]()
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