who invented the first mechanical clock in 1300
History of timekeeping devices The first geared clock was invented in the 11th century by the Arab engineer Ibn Khalaf al-Muradi in Islamic Iberia; it was a water clock that employed a complex gear train mechanism, including both segmental and epicyclic gearing,[4][83] capable of transmitting high torque. The clock was unrivalled in its use of sophisticated complex gearing, until the mechanical clocks of the mid-14th century.[83] Al-Muradi's clock also employed the use of mercury in its hydraulic linkages,[84][85] which could function mechanical automata.[85] Al-Muradi's work was known to scholars working under Alfonso X of Castile,[86] hence the mechanism may have played a role in the development of the European mechanical clocks.[83] Other monumental water clocks constructed by medieval Muslim engineers also employed complex gear trains and arrays of automata.[87] Like the earlier Greeks and Chinese, Arab engineers at the time also developed a liquid-driven escapement mechanism which they employed in some of their water clocks. Heavy floats were used as weights and a constant-head system was used as an escapement mechanism,[4] which was present in the hydraulic controls they used to make heavy floats descend at a slow and steady rate.[87]
Circadian rhythm In 1896, Patrick and Gilbert observed that during a prolonged period of sleep deprivation, sleepiness increases and decreases with a period of approximately 24 hours.[9] In 1918, J.S. Szymanski showed that animals are capable of maintaining 24-hour activity patterns in the absence of external cues such as light and changes in temperature.[10] In the early 20th century, circadian rhythms were noticed in the rhythmic feeding times of bees. Extensive experiments were done by Auguste Forel, Ingeborg Beling, and Oskar Wahl to see whether this rhythm was due to an endogenous clock.[citation needed] Ron Konopka and Seymour Benzer isolated the first clock mutant in Drosophila in the early 1970s and mapped the "period" gene, the first discovered genetic determinant of behavioral rhythmicity.[11] Joseph Takahashi discovered the first mammalian circadian clock mutation (clockÎ”19) using mice in 1994.[12][13] However, recent studies show that deletion of clock does not lead to a behavioral phenotype (the animals still have normal circadian rhythms), which questions its importance in rhythm generation.[14][15]