Time Keeping

Time Keeping

Published: 2002

The Islamic Calendar
The Islamic Calendar (or Hijri calendar) is purely lunar. It contains 12 months based on the moon’s motion, and because 12 synodic months are only 12 x 29.53=354.36 days, the Islamic calendar is consistently shorter than a tropical year. Therefore it shifts concerning the Christian calendar. The calendar is based on the Qur’an (Sura IX, 36-37), and its proper observance is a sacred duty for Muslims. The Islamic calendar is the official calendar in countries around the Gulf, especially Saudi Arabia. But other Muslim countries use the Gregorian calendar for civil purposes and only turn to the Islamic calendar for religious purposes.

Islamic Timekeeping Water Clock
What is Taught:
Until the 14th century, the only type of clock available was the water clock. In 1335, a large mechanical clock was erected in Milan, Italy. This was possibly the first weight-driven clock.

What Should be Taught:
A variety of mechanical clocks were produced by Spanish Muslim engineers, both large and small, and this knowledge was transmitted to Europe through Latin translations of Islamic books on mechanics. These clocks were weight-driven.

Designs and illustrations of epi-cyclic and segmental gears were provided. One such clock included a mercury escapement. Europeans directly copied the latter type during the 15th century. Besides, during the 9th century, Ibn Firnas of Islamic Spain, according to Will Durant, invented a watch-like device that kept accurate time. The Muslims also constructed a variety of highly accurate astronomical clocks for use in their observatories.

What is Taught:
In the 17th century, the pendulum was developed by Galileo during his teenage years. He noticed a chandelier swaying as the wind was blowing it. As a result, he went home and invented the pendulum.

What Should be Taught:
Ibn Yunus al-Masri discovered the pendulum during the 10th century, who was the first to study and document its oscillatory motion.
Muslim physicists introduced its value for use in clocks during the 15th century.