It is a rare achievement for a scholar to take what could be the dull history of a technical subject and convert it into
pleasurable reading for the layperson. However, Ken Alder, a history professor at Northwestern University, has done just that in ‘The Measure of All Things.’ The subject of the book, in its broadest sense, is the beginnings of the metric system in revolutionary France and how the metric system has affected our world. The narrower focus is the work of two notable astronomers and surveyors: Jean-Baptiste-Joseph Delambre (1749-1822) and his colleague, Pierre-François-Andre Méchain (1744-1804.)
The basic concept of the metric system had originated before the Revolution, but few refinements had been made. The Revolution itself was a time of intense turmoil in France, in which governments changed violently and the leaders at one time could become the guillotined victims of their successors. However, a consistent goal throughout this turbulent period was to ‘rationalize’ life in France, spread rationality to all mankind, and this was to include rationalizing sytems of
measurement. A meter had been defined in the abstract as one ten-millionth of a quarter
meridian (or one ten-millionth of the distance between either pole and the equator) but how is one to actually represent this physically, in the form of a bar or rod divided into tenths, hundredths and thousands that could be publicly displayed as a standard for all to use? One task of Delambre and Méchain was to create such an object.
It may be difficult for us to imagine a world in which standards of measurement in one city could be significantly different from standards followed in a neighboring locality a day’s walk away but still in the same kingdom. Yet this had been the situation in France and generally in Europe for centuries. Attempts had been made in medieval times to standardize linear measurements and weights for the marketplace of a single town by placing standards on display in local cathedrals, but the difficulties the old condition created for commerce at a national and international level were immense. Revolutionary France proposed to do away with the ancient impediments, standardize all measurements, simplify them by decimalization (the number of fingers on two hands is ten) and spread the concept throughout Europe.
Delambre and Méchain were to set the basis for detailed mapping of France by creating a gigantic chain of triangles running from Dunkirk in the north through Paris to Barcelona in Spain, along a meridian that was to be the ‘meridian of Paris.’ This was to be a French ‘prime meridian’ that was displaced by the Greenwich Meridian near London only in the late nineteenth century, when British sea power dominated world commerce. In establishing the precise length of such a meridian for mapping, it was also hoped that a meter could then be triangulated precisely, assuming that the earth is a perfect sphere, which, unfortunately, it is not.
In narrating the careers of the two astronomers, Alder not only portrays two individuals who are interesting in themselves, but brings in a discussion of a critical period in world history, emphasizing a seminal time in the evolution of science. Such individuals as Lalande and Laplace, even more famous as astronomers than Delambre and Méchain, were involved somewhat indirectly in the great work. Also, there was Lavoisier, one of the principal founders of modern chemistry, and Legendre, who used the multitudinous measurements of Mechain and Delambre to become one of the founders of modern statistics. Méchain was a very exacting individual of a highly nervous and overanxious temperament, while Delambre was more phlegmatic. When it was discovered that Méchain’s attempt to establish the meter was minutely inaccurate, his health collapsed and he died at a relatively young age. Delambre lived longer to become one of the leading members of the French Academy of Sciences.
Alder concludes by discussing the sstatus of the metric system in the contemporary world. Before the twentieth century, almost all countries had adopted the metric system in its entirety, while the United States, Britain and the British Commonwealth were the major holdouts. Britain decided to gradually become metric only in 1965, when it decided to join the European Economic Community. But metrification has been a topic of intense controversy in Britain and complete adoption has dragged, as it has in Canada, where Celsius temperatures and kilometers have become part of everyday thinking, while weights in grocery stores are in both pounds and kilograms. By the start of the twenty-first century, the only significant non-metric nation was the United States. Alder examines the complex reasons why Americans have held back, but points out that the US at least rigorously standardized the ‘English system’ on a national level shortly after the Revolution. Thus, Americans antedated even the French in at least rationalizing their system of measurement to that extent.