Kater's pendulum minutes per day slower than at Paris, or equivalently the length of a pendulum with a swing of one second there was 1¼ Paris "lines", or 2.6 mm, shorter than at Paris. It was realized by the scientists of the day, and proven by Isaac Newton in 1687, that this was due to the fact that the Earth was not a perfect sphere but slightly oblate; it was thicker at the equator because of the Earth's rotation. Since the surface was farther from the Earth's center at Cayenne than at Paris, gravity was weaker there. Since that time pendulums began
Foucault pendulum vector diagrams of zero degrees equals 1. There are 90 degrees of misalignment at the Equator and the cosine of 90 degrees equals 0. formula_13 = formula_14 = formula_15 This equation is very similar to the equation for the reduction in surface velocity with longitude stated above. This is equivalent to stating that the angular velocity that is imparted to the pendulum bob decreases with the sine of the latitude of the location (the sine of 90 degrees latitude equals 1; the sine of zero degrees latitude equals 0). The time to observe a complete rotation is inversely proportional to the angular