The obvious plan was to make such alterations in the Paris system as were strictly necessary, keeping to the main standards of length and capacity, standards not irreconcilable, and to make it obligatory throughout France. As Napoleon said, ‘It was so simple that it could have been done in twenty-four hours, and adopted throughout France in less than a year.’
Amendments such as I have sketched in the last chapter would have answered the purpose sufficiently.
The ostensible plan of the new system of weights and measures was (May 8, 1790) ‘to create them anew on invariable bases, and to establish in commercial calculations the uniformity which Reason has vainly called for during so many centuries, and which must form a new bond between men.’
Even this scientific and fraternal plan, at first on the basis of a normal pendulum-length, 3/4 inch longer than the half-toise (as proposed by James Watt in 1783), might have been carried out so as to disturb the hereditary ideas and customs of the people as little as possible. But it was resolved to take a geodesical basis. This, taken afresh and not accurately, for the metre, was already at hand in a toise equal to the Olympic fathom, 1/1000 of the meridian mile. And in the report to the Convention, it was recognised that the most ancient people had measures derived from the terrestrial meridian.
More than two centuries before the Revolution an abbé (Mouton) had proposed a revival of the Olympic system, decimalised from the meridian mile down to a digit, 1/100 of the fathom.
Without this decimalisation, at least in the popular series of measures, there was a geodesic basis—for this was resolved as necessary—already at hand in the Olympic system, and the Olympic foot cubed would have given a unit of capacity and the Olympic talent one of weight, all the more suitable inasmuch as 1/1000 of it would have been an ounce = 453·6 grains, closely approximating to the Cologne ounce and therefore likely to be acceptable in other countries. But the real object was to make a clean sweep of the past; and the formation of a Republican system of measures was entrusted to mathematicians and other scientists who did not consider that a system convenient to them might be very inconvenient to unscientific people. The division of all measures must be on an obligatory decimal system convenient to mathematicians and most inconvenient to nearly everyone else.