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The second pendulum, ... The seconds pendulum's length is a mean to measure g, the local acceleration due to local gravity and centrifugal acceleration, ...
The seconds pendulum, a pendulum with a period of two seconds so each swing takes one second, was widely used to measure gravity, because its period could be easily measured by comparing it to precision regulator clocks, which all had seconds pendulums. By the late 17th century, the length of the seconds pendulum became the standard measure of ...
In coordination with scientists in France, Jefferson selected the seconds pendulum at 45° latitude as the basic reference. For technical reasons, he proposed using a uniform rod as the pendulum rather than a traditional pendulum. The pendulum was estimated to be 39.14912 English inches long (which at that time was not yet defined to be exactly ...
While there he also measured the length of a seconds pendulum, that is a pendulum with a half-swing of one second, and found it to be 1.25 lignes (2.256 millimeters*) shorter than at Paris. [3] His method [ 4 ] [ 5 ] was to compare the oscillation of a freely decaying pendulum with the time kept by another mechanical clock and astronomical ...
Forensic metrology – Science of measurement applied to forensics; History of timekeeping devices in Egypt; Quantum metrology – Application of quantum entanglement to high-precision measurement; Quartz crisis – 1970s–80s watchmaking industry upheaval; Seconds pendulum – Pendulum whose period is precisely two seconds
Gravity measurements are always referenced to sea level. He gave his result as the length of the seconds pendulum. After corrections, he found that the mean length of the solar seconds pendulum at London, at sea level, at 62 °F (17 °C), swinging in vacuum, was 39.1386 inches. This is equivalent to a gravitational acceleration of 9.81158 m/s 2 ...
If SI units are used (i.e. measure in metres and seconds), and assuming the measurement is taking place on the Earth's surface, then g ≈ 9.81 m/s 2, and g / π 2 ≈ 1 m/s 2 (0.994 is the approximation to 3 decimal places).
He made a careful study of the contemporary state of weights and measures before proposing reform in the British House of Commons on 5 February 1790. [3] In France, Charles Maurice Talleyrand was pursuing similar goals with a unit of length based on the seconds pendulum, as was Thomas Jefferson in the US having been charged by President George Washington with measurement reform.