He derives the formula for the length of a mathematical seconds pendulum at any place on the Earth, compares it with that of de Prony's formula for the length of physical seconds pendulum.
22.
He derives the formula for the length of a mathematical seconds pendulum at any place on the Earth, compares it with that of de Prony's formula for the length of physical seconds pendulum.
23.
From 1824, the basic unit was defined as a " fot " being derived from astronomy as the length of a one-second pendulum times 12 / 38 at a latitude of 45?
24.
While on passage to join his ship, he struck up a close friendship with Captain Edward Sabine, who was travelling to Africa to commence a series of observations on the length of the seconds pendulum.
25.
Combining these instruments he tried to determine a standard of length by use of a seconds pendulum ( initially a Foucault pendulum, later he ordered a Repsold reversible pendulum which arrived shortly after his death ).
26.
In 1790, then US Secretary of State Thomas Jefferson proposed to Congress a comprehensive decimalized US'metric system'based on the seconds pendulum at 38?North latitude, the mean latitude of the United States.
27.
If I remember right, a foot was to be one fifth of the swing width of a seconds pendulum ( one fifth in order to make the metric foot close in length to the traditional foot ).
28.
By the end of the 18th century, when many nations were reforming their weight and measure systems, the seconds pendulum was the leading choice for a new definition of length, advocated by prominent scientists in several major nations.
29.
By measuring the length of a seconds pendulum in different latitudes, one can calculate the " oblateness " of the Earth-i . e . the degree to which the " figure of the Earth " departs from perfect sphericity.
30.
However, it was soon discovered that the length of a seconds pendulum varies from place to place : French astronomer Jean Richer had measured the 0.3 % difference in length between Cayenne ( in French Guiana ) and Paris.
