== The Measure Of All Things == === The Seven-Year Odyssey and Hidden Error That Transformed the World === === Ken Alder, 2002 | Central 526.1 A361m 2002 === Have copy at Hollyberry ----- Also by Ken Alder, [[ https://www.goodreads.com/book/show/8850267-engineering-the-revolution | Engineering the Revolution ]] Arms and Enlightenment in France, 1763-1815 ... 18th century history defined by the gun, probably not interesting ----- [[ https://en.wikipedia.org/wiki/Geodesy | geodesy ]] [[ https://en.wikipedia.org/wiki/History_of_the_metre#Meridional_definition | Meridional definition ]] Front Illustration: Map from Dunkerque to Spain, through Amiens, Paris, Bourges, and the mountains to the south, reaching the Mediterranean Sea 20 km west of Barcelona. The map shows the triangles used. It is clear how the angles were measured with a Borda (actually assistant [[ https://en.wikipedia.org/wiki/%C3%89tienne_Lenoir_(instrument_maker) | Etienne Lenoir ]] ) [[ https://en.wikipedia.org/wiki/Repeating_circle | repeating circle theodolite ]], and that given the angles and one measured sides, all the sides of all the triangles can be computed ... still, that is a LOT of iterated extrapolation and accumulating error. p196 baseline measured with suveyor's chain [[ https://en.wikipedia.org/wiki/Jean_Baptiste_Joseph_Delambre | Jean Baptiste Joseph Delambre ]] measured the meridian from [[ https://en.wikipedia.org/wiki/Dunkirk | Dunkirk ]] to [[ https://en.wikipedia.org/wiki/Rodez | Rodez ]] in the south of France [[ https://en.wikipedia.org/wiki/Pierre_M%C3%A9chain | Pierre Méchain ]] measured from Rodez to [[ https://en.wikipedia.org/wiki/Castell%C3%B3n_de_la_Plana | Castellón de la Plana ]] The Méchain Wikipedia article describes the survey "error" of 0.23mm / meter ( 0.023% ) resulting from hundreds of rough country measurements through mountains. Méchain tweaked his measurements to make them appear more precise, but his result was no worse than an accurate reporting of those ambitious/difficult/error-laden measurements. No "Hidden Error" transforming the world. The world is what it is, and a 230 ppm error in the origin of the meter is a heck of a lot better than the thousands of idiosyncratic local measurements plaguing pre-revolution France This is more about a valiant struggle to generate a non-arbitrary definition of the meter from a measurement of the planet Earth. CorrectingTheEarthToMatchTheMeter