The elephant clock was a medieval Muslim invention by al-Jazari (1136–1206), consisting of a weight powered water clock in the form of an elephant. The various elements of the clock are in the housing on top of the elephant. They were designed to move and make a sound each half hour. A modern full-size working reproduction can be found as a centrepiece in the Ibn Battuta Mall, a shopping mall in Dubai, United Arab Emirates. Another working reproduction can be seen outside the Musée d'Horlogerie du Locle, Château des Monts, in Le Locle, Switzerland.
Mechanism
----------------------------
The timing mechanism is based on a water-filled bucket hidden inside the elephant. In the bucket is a deep bowl floating in the water, but with a small hole in the centre. The bowl takes half an hour to fill through this hole. In the process of sinking, the bowl pulls a string attached to a see-saw mechanism in the tower on top of the elephant. This releases a ball that drops into the mouth of a Serpent, causing the serpent to tip forward, which pulls the sunken bowl out of the water via strings. At the same time, a system of strings causes a figure in the tower to raise either the left or right hand and the mahout (elephant driver at the front) to hit a drum. This indicates a half or full hour. Next the snake tips back. The cycle then repeats, as long as balls remain in the upper reservoir to power the emptying of the bowl.
This was the first clock in which an automaton reacted after certain intervals of time. In the mechanism, a humanoid automata strikes the cymbal and a mechanical bird chirps, like in the later cuckoo clock, after every hour or half hour.
Another innovative feature of the clock was how it recorded the passage of temporal hours, which meant that the rate of flow had to be changed daily to match the uneven length of days throughout the year. To accomplish this, the clock had two tanks, the top tank was connected to the time indicating mechanisms and the bottom was connected to the flow control regulator. At daybreak the tap was opened and water flowed from the top tank to the bottom tank via a float regulator that maintained a constant pressure in the receiving tank.
The mechanism employed a flow regulator, which was used here to determine the time when the clock strikes at hourly intervals. The hourly intervals were determined with the use of a small opening in a submersible float, which was calibrated to give the required rates of flow under different water rates.
The float regulator was later a common mechanism during the Industrial Revolution of the 18th century, when it was employed in the boiler of a steam engine and in domestic water distribution systems.
This appears to be an early example of a closed-loop system in a mechanism. The clock functioned as long as there were metal balls in its magazine.
Mechanism
----------------------------
The timing mechanism is based on a water-filled bucket hidden inside the elephant. In the bucket is a deep bowl floating in the water, but with a small hole in the centre. The bowl takes half an hour to fill through this hole. In the process of sinking, the bowl pulls a string attached to a see-saw mechanism in the tower on top of the elephant. This releases a ball that drops into the mouth of a Serpent, causing the serpent to tip forward, which pulls the sunken bowl out of the water via strings. At the same time, a system of strings causes a figure in the tower to raise either the left or right hand and the mahout (elephant driver at the front) to hit a drum. This indicates a half or full hour. Next the snake tips back. The cycle then repeats, as long as balls remain in the upper reservoir to power the emptying of the bowl.
Automaton
This was the first clock in which an automaton reacted after certain intervals of time. In the mechanism, a humanoid automata strikes the cymbal and a mechanical bird chirps, like in the later cuckoo clock, after every hour or half hour.
Passage of temporal hours
Another innovative feature of the clock was how it recorded the passage of temporal hours, which meant that the rate of flow had to be changed daily to match the uneven length of days throughout the year. To accomplish this, the clock had two tanks, the top tank was connected to the time indicating mechanisms and the bottom was connected to the flow control regulator. At daybreak the tap was opened and water flowed from the top tank to the bottom tank via a float regulator that maintained a constant pressure in the receiving tank.
Flow regulator
The mechanism employed a flow regulator, which was used here to determine the time when the clock strikes at hourly intervals. The hourly intervals were determined with the use of a small opening in a submersible float, which was calibrated to give the required rates of flow under different water rates.
The float regulator was later a common mechanism during the Industrial Revolution of the 18th century, when it was employed in the boiler of a steam engine and in domestic water distribution systems.
Closed-loop system
This appears to be an early example of a closed-loop system in a mechanism. The clock functioned as long as there were metal balls in its magazine.
No comments:
Post a Comment