Jim's GT clock: Difference between revisions

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The march of technology can be seen in Mankind's quest to mark time.  Throughout most of history, it was sufficient to see the general position of the sun in the sky during the day, or the position of the Big Dipper at night.
Ancients who were meticulous enough to want more invented the sun dial and tracked the shadow cast by a rod as the sun crossed the sky.  The rate that a candle burned downward, drops of water from a water clock, or the grains of sand passing through the throat of an hour glass were improvements that worked on cloudy days.
The first mechanical clocks were invented in Medieval Europe; clever arrangements of gears and wheels that were made to turn by weights pulled downward by the force of gravity.  They became common in churches and monasteries to call the faithful to prayers.  They could strike bells but only had an hour hand and could gain or lose up to a half an hour per day.
No clock in existence, up through 1656, could measure short intervals of time accurately, or could possibly be relied on to tell time to the minute.
In the 1590's the Italian scientist Galileo measured the speed of falling bodies using his own pulse rate.  His studies disproved the physics of Aristotle that had held for the previous eighteen centuries.  His work laid the foundation for Isaac Newton's later laws of motion.  As a teenager in 1582 Galileo had noticed the swinging chandeliers in a cathedral.  It seemed to him that
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