Pendulum the pendulum could be used to measure the force of gravity. During his expedition to Cayenne, French Guiana in 1671, Jean Richer found that a pendulum clock was minutes per day slower at Cayenne than at Paris. From this he deduced that the force of gravity was lower at Cayenne. In 1687, Isaac Newton in "Principia Mathematica" showed that this was because the Earth was not a true sphere but slightly oblate (flattened at the poles) from the effect of centrifugal force due to its rotation, causing gravity to increase with latitude. Portable pendulums began to be taken on voyages
Foucault's Pendulum Foucault's Pendulum Foucault's Pendulum (original title: "Il pendolo di Foucault" ) is a novel by Italian writer and philosopher Umberto Eco. It was first published in 1988, and an English translation by William Weaver appeared a year later. "Foucault's Pendulum" is divided into ten segments represented by the ten Sefiroth. The satirical novel is full of esoteric references to Kabbalah, alchemy, and conspiracy theory—so many that critic and novelist Anthony Burgess suggested that it needed an index. The pendulum of the title refers to an actual pendulum designed by French physicist Léon Foucault to demonstrate Earth's rotation, which has symbolic