A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 1/2 Hz.
At standard gravity its length is 0.994 m (39.1 in). This length was determined (in toises) by Marin Mersenne in 1644. In 1660, the Royal Society proposed that it be the standard unit of length. In 1675 Tito Livio Burattini proposed that it be named the meter. In 1790, one year before the metre was ultimately based on a quadrant of the Earth, Talleyrand proposed that the metre be the length of the seconds pendulum at a latitude of 45°. This option, with one-fifth of this length defining the foot, was also considered by Thomas Jefferson and others for redefining the yard in the United States shortly after gaining independence from the British Crown.
In 1670 the seconds pendulum was employed by William Clement in his improved version of the original pendulum clock by Christian Huygens, creating the longcase clock which could tick seconds.
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Famous quotes containing the words seconds and/or pendulum:
“Watching fifteen seconds of nasal passages unblocking sure beats watching thirty seconds.”
—Barbara Lippert, U.S. advertising critic. As quoted in Newsweek magazine, p. 8 (June 16, 1986)
“During the first World War women in the United States had a chance to try their capacities in wider fields of executive leadership in industry. Must we always wait for war to give us opportunity? And must the pendulum always swing back in the busy world of work and workers during times of peace?”
—Mary Barnett Gilson (1877–?)