The Tears of Things

Signing the Convention of the Meter started, rather than ended, the process of distributing the meter. . . . For fourteen years, French engineers and British metallurgists hammered and smelted their way to a tough, durable iridium-platinum alloy.

While a British firm pounded these hard, pure bars into meter sticks with an inflexible "X" cross section, the French concentrated on producing an enormous "universal comparator" that would, by strict procedure, allow a standard length to be reproduced on another bar to within two ten-thousandths of a millimeter. It was painstaking, nerve-wracking work. When the British metal workers delivered their precious bars to the French, the operator at the conservatoire would set both the standard meter and the blank bar on the bridge of the comparator. Peering through a microscope, the operator would line up the one-meter mark on the standard. Then the operator would activate a lever, causing a diamond blade to inscribe a fine line precisely at the one-meter point on the blank. Carving subdivisions was just as difficult. The two microscopes would be set, say, ten centimeters apart. The operators would mark that length. Sliding the bar down, they would etch a second ten-centimeter length into the bar, and so on. To prepare the 30 standard bars that the international delegates would take home with them, the operators repeated this operation 13,000 times. The slightest slip with the diamond point meant starting over again with repolishing of the blank.

Finally, on Saturday, 28 September 1889, two years after Poincaré was elected to the Academy of Sciences, eighteen representatives of the contracting parties gathered in Breteuil for the final sanctioning of the meter. The president of the conference canvassed their votes --unanimous-- and then pronounced: "This prototype of the meter will from now forward represent, at the temperature of melting ice, the metric unit of length," while "this prototype [kilogram] will be considered from now on the unit of mass." All standards stood on display in the meeting room: meters sheathed by protective tubes, kilograms nested in triple glass bell jars. According to plan, each delegate ceremoniously picked a ticket from an urn, the number received assigning his country a meter stick, for which he offered a signed receipt. . . .

Later that afternoon, at 1:30 to be precise, the commission charged with depositing the international prototypes gathered in the lower basement of the Breteuil Observatory. There the delegates certified that the international prototype M would from that moment forward be enclosed in a case covered on the interior with velvet, lodged within a hard cylinder of brass, screwed tight, locked, and placed in the vault. Alongside M the standard bearers then prepared two "witnesses" for burial (meter sticks, not delegates). These metallic observers would forever testify, by the very conditions of their bodies, to anything that might befall M. In the same ceremonial interment, convention delegates sanctioned the kilogram, K, elevating and renaming it as the universal standard of mass. It too found its eternal resting place in the underground iron vault in the company of its witnesses. With two keys, and in full view of the delegates, the director of the International Bureau of Weights and Measures locked the case, secured the inner basement door with a third key, and bolted the exterior door with a fourth and a fifth key. At the conclusion of these solemn events, the president of the conference handed these latter keys in separate, sealed envelopes: one to the director of the International Bureau, one to the general guard of the National Archives, and the last to the president of the International Committee. From that time on, all three basement keys would be needed to enter the sanctum sanctorum.