Today is World Metrology Day. This year’s theme is “Measurements in daily life.” Christopher Joseph says in his introduction to A Measure of Everything: “Measurement, in one form or another, is one of mankind’s oldest and most vital activities…. The earliest historical record of a unit of measurement is the Egyptian cubit, in around 3000 B.C.E., decreed to be equal to the length of a forearm and hand… plus the width of Pharaoh’s palm… by 2500 B.C.E., the necessary leap forward had been taken. The complicated and rather imprecise definition had been simplified drastically: a cubit was the same length as the prototype cubit, stored safely from harm. This was the ‘royal master cubit,’ a black marble rod some 52 cm in length–and the size of the user’s forearm was no longer an issue. From this simple model it becomes possible to measure many things: distances, areas, volumes, even masses.”

Following the 1790 decrees by the French National Assembly, the Convention of the Metre (Convention du Mètre) was signed in Paris in 1875 by representatives of seventeen nations, creating the International Bureau of Weights and Measures (BIPM). The BIPM “acts in matters of world metrology, particularly concerning the demand for measurement standards of ever increasing accuracy, range and diversity, and the need to demonstrate equivalence between national measurement standards.”