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
In Which We Serve Association Award for Best Foreign Film in 1943. A Region 2 DVD with a running time of 96 minutes was released by Carlton on 11 October 1999. A Region 1 DVD was released as part of the David Lean Collection by MGM on 7 September 2004. It features subtitles in English, Spanish and French and an English audio track in Dolby Digital 1.0. In March 2012, The Criterion Collection released "In Which We Serve" on Blu-ray and DVD as part of the "David Lean Directs Noel Coward" Box Set, which includes a short documentary on the making of "In Which