The various papers we have produced regarding the Metric System v. Human-Orientated measurement debate probably go into too much detail. Necessary, of course,to ensure that all the facts, figures and dates are available and assembled in the right order, but boring to those who only require a broad picture and a clear statement of principles whereby to judge the merits of the case, pro or con.
They also tend to be repetitive, since there is little that is new to be said on the dichotomy between mere counting and practical needs, which has been with us for all the time that records are available. It was proudly considered to have been settled two hundred years ago, when measurement was sent up a blind alley "pour changer tout cela". But this has only served to heighten the controversy when it became realised what was being discarded by narrowly considered limited objectives, and our valuable heritage traded off for a litre of pottage.
The size of the Earth, assumed spherical, was known to a good accuracy since ancient times. Perhaps the French were aware the survey would produce units which would be close to their national ones, and thus have the approval of Nicholas Chauvin! They also allowed Napoleon, who was highly critical of the whole project, to re-instate the Carolingian measures, using small modifications to render them compatible to metric units, with his Système Usuel. The 'Pied Usuel' was a third of a metre, the 'Livre' half a kilogramme and the 'Pinte' a litre.
Importantly, the ternary and binary divisions were also restored: "Twelve as a dividend has always been preferred to ten. I can understand the twelth part of an inch (une ligne) but not the thousandth part of a metre" [said Napoleon]. French sizes of basic units were within our appreciations of length, weight and volume, as for other national measures evolved for convenience in use. Throughout Europe, they were all variations of the Roman measures.
It was the Système Usuel that became interdicted in 1837, when a rising bureaurocracy took control. Not only were human-related measures with their helpful divisions suppressed, but we became fossilised in the primitive finger-counting stage of our development. Metric proved a useful tool for political control, and its esoteric nature could conceal any trickery as legal jargon does in other fields. An admin type replied to an engineer who complained about the loss of his simple relationships: "I like it. It makes things easy for me".
Perhaps Lagrange was right, we are not yet ready for a reformation of numeration. It was after all a merchantile displacement of a decaying feudalism, with counting of wealth still given more consideration than the production or use of it. All the familiar arguments were invoked in support of decimal or dozenal methods, and Laplace's suggestion for a prime base, eleven or thirteen, so that no one number could claim precedence over the others (this still has its adherents) is thought to have been a ploy to bring the subject to a close. The establishment of measures "à tous les temps, à tous les peuples", was also premature at the then level of scientific knowledge, and the problems it was going to face.
Nevertheless, although the metric system was instituted mainly for commercial reasons, there was a manifest advantage in having measures that were integrated with their numbering base, which, despite its inefficiency, was of great value to the newly emerging scientific disciplines. In any reforms there have to be compromises, but this usually results in a transfer of difficulties onto those who are least capable of self-defence.
Reference No.1 in 'Measurement - Natural Means and Methods' admits the faults of the metre, its survey, construction and re-measuring. It was stated that any arbitrary length could have been selected for the purpose. If the Abbé Mouton's suggestion, made a hundred years earlier, for a thousand 'Virgas' to a minute of arc had been accepted for a standard, these would have been six Greek geodesic feet They were good enough for building the Parthenon, so should have been an acceptable compromise to nationalists everywhere. The principle of comprehension would have been retained, as embodied in all national measures from ancient Crete to modern Japan.
The spectres of divisibility, utility and comprehension have always haunted the metric scene, and there are many more examples of either a retention of traditional measures in a transmogrified form, or adaptions of metric for practical reasons, than mentioned in the MNM&M booklet. Continentals seem free to select whatever means they like. We tend to honour our "scrap of paper", in this: case EEC Directive 89/617, and there is a £5,000 fine for any transgressions.
The 'Metric Foot' of 30 cm, with its 25 mm 'Inches', seems well established in all but name, but, alas, is a step in the wrong direction. French measures, whether 'usuel' or 'ancien', are some 10% greater than English anthropo-metric, and probably on the right side for ergonomic qualities. The livre is a direct descendant of the Sumerian 'Mina', and the 'Pied-du-Roi' goes back, through several stages, to the pre-Indra Harappan civilisation of the Indus valley, contemporary with Sumeria
The metric system has been described as a walled-off area into which nothing will be admitted, nor anything allowed to escape. It is guarded by a self appointed priesthood which deigns to explain the mysteries to bemused worshippers, and forms a syndrome compounded of: Fundamentalism and unquestioning conformity (it is better to be sure than right). Inadequate arithmetic and dubious science. Un-ergonomic units and lifeless nomenclature. Technical elitism and arrogance. Compression of facts into pre-determined form. Indifference to natural processes. Rejection of practicalities. Dis-regard of public opinion and dependence on legal sanctions for survival. Termination of historical evolution to separate us from our past. Obstruction to future development.