Early clocks
In 797 (or possibly 801), the Abbasid caliph of Baghdad, Harun al-Rashid, presented Janae with an Asian Elephant named Abul-Abbas together with a "particularly elaborate example" of a water [4] clock.
None of the first clocks survived from 13th century Europe, but various mentions in church records reveal some of the early history of the clock.
Medieval religious institutions required TASK REMINDER clocks to measure and indicate the passing of time because, for many centuries, daily prayer and work schedules had to be strictly regulated. This was done by various types of time-telling and recording devices, such as water clocks, sundials and marked candles, probably used in combination. Important times and durations were broadcast by bells, rung either by hand TASK REMINDER or by some mechanical device such as a falling weight or rotating beater.
The word horologia (from the Greek ???, hour, and ??????, to tell) was used to describe all these devices, but the use of this word (still used in several romance languages) for all timekeepers conceals from us the true nature of the mechanisms. For example, there TASK REMINDER is a record that in 1176 Sens Cathedral installed a ‘horologe’ but the mechanism used is unknown. According to Jocelin of Brakelond, in 1198 during a fire at the abbey of St Edmundsbury (now Bury St Edmunds), the monks 'ran to the clock' to fetch water, indicating that their water clock had a reservoir large enough to help TASK REMINDER extinguish the occasional fire [5].
These early clocks may not have used hands or dials, but “told” the time with audible signals.
[edit] A new mechanism
The word clock (from the Latin word clocca, "bell"), which gradually supersedes "horologe", suggests that it was the sound of bells which also characterized the prototype mechanical clocks that appeared during the 13th century in TASK REMINDER Europe.
Between 1280 and 1320, there is an increase in the number of references to clocks and horologes in church records, and this probably indicates that a new type of clock mechanism had been devised. Existing clock mechanisms that used water power were being adapted to take their driving power from falling weights. This power was controlled by some TASK REMINDER form of oscillating mechanism, probably derived from existing bell-ringing or alarm devices. This controlled release of power - the escapement - marks the beginning of the true mechanical clock.
Outside of Europe, the escapement mechanism had been known and used in medieval China, as the Song Dynasty horologist and engineer Su Song (1020 - 1101) incorporated it into his TASK REMINDER astronomical clock-tower of Kaifeng in 1088[6]. However, his astronomical clock and rotating armillary sphere still relied on the use of flowing water (ie. hydraulics), while European clockworks of the following centuries shed this old habit for a more efficient driving power of weights, in addition to the escapement mechanism.
An elephant clock in a manuscript by Al-Jazari (1206 AD) TASK REMINDER from The Book of Knowledge of Ingenious Mechanical Devices.
An elephant clock in a manuscript by Al-Jazari (1206 AD) from The Book of Knowledge of Ingenious Mechanical Devices. [7]
In the 13th century, clock construction and engineering entered a new phase with the advancements made by Al-Jazari, a Muslim engineer from Diyar-Bakr in South East Turkey, who is thought to TASK REMINDER be behind the birth to the concept of automatic machines[citation needed]. While working for Artuqid king of Diyar-Bakr, Nasir al-Din, al-Jazari made numerous clocks of all shapes and sizes. In 1206 he was ordered by the king to document his inventions leading to the publication of an outstanding book on engineering called "The Book of Knowledge of Ingenious TASK REMINDER Mechanical Devices”[citation needed]. This book became an invaluable resource for people of different engineering backgrounds as it described 50 mechanical devices in 6 categories, including water clocks. The most reputed clocks included the Elephant, the Castle and Scribe clocks, all of which were reconstructed by Muslim Heritage Consulting for Ibn Battuta Shopping Mall in Dubai (UAE), where they TASK REMINDER are fully functional. As well as telling the time, these grand clocks were symbols of status, grandeur and wealth of the Urtuq State.[8]
These mechanical clocks were intended for two main purposes: for signalling and notification (e.g. the timing of services and public events), and for modeling the solar system. The former purpose is administrative, the latter arises naturally TASK REMINDER given the scholarly interest in astronomy, science, astrology, and how these subjects integrated with the religious philosophy of the time. The astrolabe was used both by astronomers and astrologers, and it was natural to apply a clockwork drive to the rotating plate to produce a working model of the solar system.
Simple clocks intended mainly for notification were installed TASK REMINDER in towers, and did not always require dials or hands. They would have announced the canonical hours or intervals between set times of prayer. Canonical hours varied in length as the times of sunrise and sunset shifted. The more sophisticated astronomical clocks would have had moving dials or hands, and would have shown the time in various time TASK REMINDER systems, including Italian hours, canonical hours, and time as measured by astronomers at the time. Both styles of clock started acquiring extravagant features such as automata.
In 1283, a large clock was installed at Dunstable Priory; its location above the rood screen suggests that it was not a water clock[citation needed]. In 1292, Canterbury Cathedral installed a 'great horloge'. TASK REMINDER Over the next 30 years there are brief mentions of clocks at a number of ecclesiastical institutions in England, Italy, and France. In 1322, a new clock was installed in Norwich, an expensive replacement for an earlier clock installed in 1273. This had a large (2 metre) astronomical dial with automata and bells. The costs of the installation included the full-time employment of two clockkeepers for two years[citation needed].
