Times Pendulum - The quest to capture time - from Sundials to Atomic Clocks
by Barnett, Joe Ellen
pub by Plenum Press, NY, 1998 -     - - isbn 0-306-45787-3 -   - 340 p. total   -   - Contents   -   Introduction p. 3-10   -     -   References p. 315-329   - few diagrams   - index p. 333-340     About the Author p. back flap of dustjacket
This book begins by saying that the concept of TIME is not definable. In history even great thinkers of the ages do not seem to be able to define exactly what time is.
After that the book continues with the development on how mankind has developed machines to measure time, and what time is measured. For most of the history of humanity time was measured by measuring what is viewed in the sky. Day and night, then the seasons, but also the phases of the moon. For millennia the most accurate time pieces were sundials. Water clocks and sand clocks were used to measure time within a day and a night.
Clocks which had mechanical movements were developed. They were only moderately accurate, but between them and their predecessors people could determine when to pray.
In 1656 by Christiaan Huygens invented pendulum clocks as we know them. They were developed more and more finely to the extent that the time they kept could challenge the time told us by the movements of the Sun and heavenly bodies. We realized that time can be measured more finely than is revealed by our measurements of the movements of the heavens.
The quartz clock, measuring the vibrating of a crystal was the next major refinement in 1927. Since then that has been further refined by other vibration measurements to our modern Atomic clocks.
The measurement of past time into the foggy mists has also been refined. We used to make estimates of the thickness of the layers of sedimentary deposits but more recently measure the past by the decay of atomic particles from a stable or unstable position in the distant past to the situation such particles are in now. Radio carbon dating is widely used, but for measurements further past we can use other isotopes and measure to the billions of years.
This is a thoroughly interesting book. It might cause one to think about time, and how one uses our measurement of time in and to control our own lives.
I note that when the author is writing about things outside her areas of expertise she makes some blunders, but none that have any effect on her examination of the concept and measurement of TIME,.
~ 2018-05- ~

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