0.075 meters Traditional Cache

The timeline of meter definitions

• 8 May 1790 – The French National Assembly decides that the length of the new meter would be equal to the length of a pendulum with a half-period of one second.
• 30 March 1791 – The French National Assembly accepts the proposal by the French Academy of Sciences that the new definition for the meter be equal to one ten-millionth of the length of a quadrant along the Earth's meridian through Paris, that is the distance from the equator to the north pole.
• 1795 – Provisional meter bar constructed of brass. Based on Bessel's ellipsoid and legally equal to 443.44 lines on the toise du Pérou (a standard French unit of length from 1747).
• 10 December 1799 – The French National Assembly specifies the platinum meter bar, constructed on 23 June 1799 and deposited in the National Archives, as the final standard. Legally equal to 443.296 lines on the toise du Pérou.
• 28 September 1889 – The 1st General Conference on Weights and Measures (CGPM) defines the meter as the distance between two lines on a standard bar of an alloy of platinum with 10% iridium, measured at the melting point of ice.
• 6 October 1927 – The 7th CGPM redefines the meter as the distance, at 0 °C (273 K), between the axes of the two central lines marked on the prototype bar of platinum-iridium, this bar being subject to one standard atmosphere of pressure and supported on two cylinders of at least 10 mm (1 cm) diameter, symmetrically placed in the same horizontal plane at a distance of 571 mm (57.1 cm) from each other.
• 14 October 1960 – The 11th CGPM defines the meter as 1650763.73 wavelengths in a vacuum of the radiation corresponding to the transition between the 2p10 and 5d5 quantum levels of the krypton-86 atom.
• 21 October 1983 – The 17th CGPM defines the meter as the length of the path traveled by light in a vacuum during a time interval of 1/299 792 458 of a second.