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CORPUS CLOCK.
The Commissioning
of the Corpus Clock. The Corpus Clock has been
invented and designed by Dr John Taylor for Corpus Christi College Cambridge for
the exterior of the college's new library building. It will be unveiled on 19
September by Prof Stephen Hawking, cosmologist and author of the global
bestseller, A Brief History of Time. The £1 million timepiece, known
as The Corpus Clock, has been commissioned and designed to honour John Harrison,
who was famously the pioneer of longitude and inventor of the esoteric clock
mechanism known as a grasshopper escapement. The clock has been designed by
the inventor and horologist Dr John Taylor and makes ingenious use of the
grasshopper escapement, moving it from the inside of the clock to the outside
and refashioning it as a Chronophage, or time-eater, which literally devours
time. Longitude and
Navigation. Longitude is simply the
difference between the observer's local (sundial) time and the local (sundial)
time at Greenwich, England. As any sundial shows, the earth turns at 15 degrees
per hour (360 degrees per day), so this time difference is easily converted into
degrees of the earth's longitude. Both local and Greenwich time must be known
onboard the observer ship to determine longitude, so finding longitude is much
more difficult than finding latitude. Either a marine chronometer or various
astronomical methods may be used to determine these two times, and therefore
longitude. To utilize accurate clocks for
the measurement of longitude while sailing the high seas was first proposed by
Gemma Frisius, in 1530. Christiaan Huygens’ tried his pendulum clock as such a
marine clock in 1664, and in 1675 invented a marine timepiece with his
spiral-spring balance wheel, but ocean tests showed that these lacked the
accuracy required for marine use. With a highly refined version, which had
technical improvements including a remontoire and temperature compensation, John
Harrison demonstrated the first sufficiently accurate marine chronometer in
1762. We therefore will start with Harrison’s contributions, and follow with the
previous and subsequent history of the three main methods of longitude
measurement. |