====== Precision pendulum clock ======
A **precision pendulum clock** is a highly accurate type of [[clock]], which was used as a time standard for public and scientific timekeeping.

Since the oscillations of the pendulum are affected by temperature and air pressure, the clocks are equipped with a [[compensating pendulum]] (invented by [[Harrison, John|John Harrison]] (1693-1776)). Sometimes the pendulum also swings in a tank, minimizing the possible interference caused by air pressure.

In very good precision clocks the time deviation does not exceed more than 1 second per month.

===== Literature =====
  *[[Das große Uhrenlexikon]]; Author [[Fritz von Osterhausen]]; ISBN 3898804305


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