According to Wikipedia, the tower clock of Norwich Cathedral constructed circa 1273 is the earliest such large clock known. ³ History Medieval documents Milan's civic clock from 1335, though Wikipedia references a Milan striking clock in 1336—a one-year discrepancy that may reflect different clocks or documents. ³ According to Wikipedia, by 1344 the clock in London's Old St Paul's Cathedral had an escapement. ³

Two independent sources agree that Salisbury Cathedral's clock dates from around 1386. ² However, Wikipedia reports doubts whether the clock currently displayed is actually the clock mentioned in 1386. ³ Similarly, Wikipedia reports that Dover Castle's clock was initially dated to the 14th century but later revised to around 1600. ³

According to Wikipedia, the verge escapement was invented in 13th-century Europe and was the earliest known type of mechanical escapement. ³ The same source reports that the verge with foliot or balance wheel was the only escapement used for the first 200 years of mechanical clock existence. ² St. Paulus-Dom Münster identifies the escapement with spindle and balance as the new innovation enabling mechanical clocks, placing the first purely mechanical clock around 1300. ¹

Open: Whether the Salisbury Cathedral clock currently displayed is the 1386 original remains unresolved; The precise mechanism by which Chinese escapement technology may have reached Europe, if at all, is documented only as a scholarly suggestion by Derek de Solla Price with no corroborating sources

According to MDPI, verge-foliot clocks had an error of approximately 300 seconds per day. ¹ The same source reports that the introduction of the pendulum in 1658 improved verge escapement accuracy by 30 times. ²

According to Wikipedia, large tower clocks were built in European town squares starting in the 13th century. ³ According to Wikipédia, the best historians of timekeeping agree mechanical clockwork originated in the late 13th century. ¹ St. Paulus-Dom Münster explicitly states that the date of the first mechanical clock carries an uncertainty of several decades. ¹ Wikipédia reports that interpretation of early documents mentioning clocks remains ambiguous regarding mechanical versus water clocks. ¹

Open: The precise mechanism by which Chinese escapement technology may have reached Europe, if at all, is documented only as a scholarly suggestion by Derek de Solla Price with no corroborating sources

Richard of Wallingford designed an astronomical clock described in the Tractatus Horologii Astronomici in 1327, corroborated by both English and French Wikipedia sources. ³ According to Wikipedia, the clock was completed about 20 years after his death and was the most complex mechanism in the British Isles at the time. ³ The same source identifies Giovanni de Dondi's astrarium as the only comparable mechanism in the 14th century. ¹

According to Italian Wikipedia, Giovanni Dondi's astronomical clock was destroyed but described in a detailed manuscript called Astrarium. ³ The source reports that Dondi's clock reproduced motions of the Sun, Moon, and five planets through gears. ²

Henri de Vic was commissioned by King Charles V of France to build a clock, confirmed by both English and French Wikipedia sources referencing the king's commission. ³ According to Wikipedia, de Vic's clock was installed in a tower of the Conciergerie in Paris in 1370. ³

Open: Whether the Salisbury Cathedral clock currently displayed is the 1386 original remains unresolved; The precise mechanism by which Chinese escapement technology may have reached Europe, if at all, is documented only as a scholarly suggestion by Derek de Solla Price with no corroborating sources

According to EBSCO, Joseph Needham claimed medieval Chinese artisans developed the escapement six centuries before Europeans. ¹ EBSCO reports that Yi Xing (also transliterated I-Xing) and collaborators devised an escapement mechanism in the early eighth century. ¹ Two Wikipedia sources corroborate this, placing Yi Xing's escapement at 723-725 AD. ²

Wikipedia reports that Yi Xing created the world's first clockwork escapement in 723-725 AD in China as part of a water-driven (hydromechanical) clock, as EBSCO terms it. ³ Wikipedia reports that Su Song built an astronomical clock tower in Kaifeng using an escapement mechanism invented by Yi Xing in 725 AD; the source does not specify the date of Su Song's tower. ² According to Wikipedia, Su Song's clock tower had 133 different clock jacks to indicate and sound the hours. ²

According to EBSCO, the Chinese hydromechanical clock was more accurate than early European mechanical clocks but had no future. ¹ Wikipedia reports that Derek J. de Solla Price suggested the Chinese escapement spread west and was the source of Western escapement technology. ² However, no documentary evidence establishes such transmission, and it remains a scholarly suggestion only. According to Wikipedia, a mercury escapement described in a Spanish document for Alfonso X in 1277 can be traced to earlier Arabic sources, indicating a parallel development track. ² Whether Chinese escapement technology influenced European clockmaking is unresolved and rests only on scholarly suggestion, not documented transmission. ²

Open: The precise mechanism by which Chinese escapement technology may have reached Europe, if at all, is documented only as a scholarly suggestion by Derek de Solla Price with no corroborating sources