Al-Jazari’s Castle Water Clock: Analysis of its Components and Functioning - II
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2. Clock's Appearance
2.1. What an Observer Would Have Seen During the Day The clock has many motions throughout the day, and would have been very pleasing to watch and listen to. From the point of view of an observer, he would have seen the sun's disc on the eastern horizon about to rise, the moon will not be seen at all and six zodiac signs are visible, while the first point of the constellation Libra is about to set. The crescent moon would steadily be travelling from left to right on the frieze, and when in between two doors the upper door opens to reveal a figure of a man, the lower door flips round to reveal a different colour. This will occur as each solar hour of sunlight has passed. Soon after this happens, the two falcons will tilt forward and spread their wings, and a ball will drop out of their beaks and into the vase. The observer will hear a cymbal like sound, and both falcons will lean back to their original position and close their wings. At the point when the sixth door is about to open, the sun is at its highest altitude, and three zodiac signs have risen from the east, and three have set on the west. The crescent moon would be between the sixth and seventh doors as the sixth door opens. It is now that the musicians will begin to play their instruments. The observer would hear and see the percussionists beat their drums very lively, and a brief moment later the observer would hear the sound of the trumpets. The two falcons would still perform their duty on this hour, and it can be concluded that the clash of cymbals would have occurred together as the percussionists started to beat their drums. This would be a fair assumption judging from the distance travelled by the lead ball, and the flow of water over the water wheel. The musicians would play at the ninth and twelfth hour. On the twelfth hour, the sun would be about to set on the western horizon, and all the zodiac signs at the start of the day would have set too. In this configuration, the zodiac disc has rotated about 180o. At this point it would have been the start of night, as the sun has set. The servant must now very quickly prepare the clock for the night ahead. 2.2. What an Observer Would Have Seen During the Night At the beginning of night the observer would see the moon on the east horizon of the clock. Light will begin to show through the first glass roundel and the crescent moon will again be moving from the left to the right of the observer. Due to the disc with 28 holes and the lamps, the moon roundel will be illuminated such that it looks similar to the phase of the actual moon for that night. When it is midnight, the crescent moon will be between the sixth and seventh door, and the sixth door figure will have fallen and opened the door. This will trigger the mechanism for the musicians to play, and also rotates the plate to deposit water in the second trough. It must be noted again that the bronze balls are not placed back in their slots for the night, as this could have been quite disturbing to hear clashing cymbals during the night. The musicians only play twice during the night, at midnight, and at daybreak, which coincides with the opening of the twelfth door. When the musicians first play at midnight, the observer would see six glass roundels illuminated with light, and by daybreak all twelve roundels would have illuminated. The servant must quickly repeat the process as it did at the beginning of the day, and this is repeated throughout the days of the year. Previous | 1 | 2 | 3 | 4 | 5 | 6 | Next
by: Prof. Salim T. S. Al-Hassani, Thu 13 March, 2008
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