Timekeeping
& Clocks
The
Islamic Calendar
The
Islamic calendar (or Hijri calendar) is a purely
lunar calendar. It contains 12 months that are
based on the motion of the moon, and because 12
synodic months is only 12 x 29.53=354.36 days,
the Islamic calendar is consistently shorter than
a tropical year, and therefore it shifts with
respect to 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.
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.
The
latter type was directly copied by Europeans during
the 15th century. In addition, during the 9th
century, Ibn Firnas of Islamic Spain, according
to Will Durant, invented a watch-like device which
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 it was
being blown by the wind. As a result, he went
home and invented the pendulum.
What Should be Taught:
The pendulum was discovered by Ibn Yunus
al-Masri during the 10th century, who was the
first to study and document its oscillatory motion.
Its
value for use in clocks was introduced by Muslim
physicists during the 15th century.
Print Page 
Email to a Friend
