advance was made towards the establishment of the "universal measure" until the French Revolution of 1789. France was particularly affected by the proliferation of length measures, and the need for reform was widely accepted across all political viewpoints, even if it needed the push of revolution to bring it about. Talleyrand resurrected the idea of the seconds pendulum before the Constituent Assembly in 1790, suggesting that the new measure be defined at 45°N (a latitude that, in France, runs just north of Bordeaux and just south of Grenoble): despite the support of the Assembly, nothing came of Talleyrand's proposal. Meridional definition The question of measurement reform was placed in the hands of the Academy of Sciences, who appointed a commission chaired by Jean-Charles de Borda. Borda was an avid supporter of decimalisation: he had invented the "repeating circle", a surveying instrument which allowed a much-improved precision in the measurement of angles between landmarks, but insisted that it be calibrated in "grades" ( of a quarter-circle) rather than degrees, with 100 minutes to a grade and 100 seconds to a minute. Borda considered that the seconds pendulum was a poor choice for a standard because the existing second (as a unit of time) was not part of the proposed decimal system of time measurement – a system of 10 hours to the day, 100 minutes to the hour and 100 seconds to the minute – introduced in 1793. Instead of the seconds pendulum method, the commission – whose members included Lagrange, Laplace, Monge and Condorcet – decided that the new measure should be equal to one ten-millionth of the distance from the North Pole to the Equator (the quadrant of the Earth's circumference), measured along the meridian passing through Paris. Apart from the obvious consideration of safe access for French surveyors, the Paris meridian was also a sound choice for scientific reasons: a portion of the quadrant from Dunkirk to Barcelona (about 1000 km, or one-tenth of the total) could be surveyed with start- and end-points at sea level, and that portion was roughly in the middle of the quadrant, where the effects of the Earth's oblateness were expected to be the largest. The Spanish-French geodetic mission had confirmed that the acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration. Indeed, we know now that the resulting acceleration towards