Numbers, please! The three original German meters

Contents

On May 20, 1875, the so-called Metre Convention was ratified in Paris. With this agreement, the signatories undertook to support meters and kilograms in science and research as well as in economic trade. To this end, the Bureau International des Poids et Mesures (BIPM) was created as an international, intergovernmental organization that still defines measurements and units today and exchanges scientific findings between its members.

Over time, the original meter and the kilogram were joined by other units of measurement, such as the second. Since 1960, the International System of Units or SI (for Système international d'unités) has been monitored and further developed and globally coordinated from there: The seven SI base units are time (second), length (meter), mass (kilogram), electric current (ampere), thermodynamic temperature (kelvin), amount of substance (mole) and luminous intensity (candela).

Zahlen, bitte!

In this section, we present amazing, impressive, informative and funny figures ("Zahlen") from the fields of IT, science, art, business, politics and, of course, mathematics every Tuesday. The wordplay "Zahlen, bitte!" for a section about numbers is based on the ambiguity of the German word "Zahlen." On one hand, "Zahlen" can be understood as a noun in the sense of digits and numerical values, which fits the theme of the section. On the other hand, the phrase "Zahlen, bitte!" is reminiscent of a waiter's request in a restaurant or bar when they are asked to bring the bill. Through this association, the section acquires a playful and slightly humorous undertone that catches the readers' attention and makes them curious about the presented numbers and facts.

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The founding members were 17 countries: Argentina, Austria-Hungary, Belgium, Brazil, Denmark, France, Germany, Italy, Peru, Portugal, Russia, Spain, Norway, Switzerland, the Ottoman Empire, the United States of America and Venezuela. Today, with 64 signatories and 37 associated countries (with less funding and without voting rights), all industrialized nations and relevant emerging economies are represented – Over 90 percent of the world's economic output has joined the agreement and created uniform measurement conditions in science and trade.

Small states also in metrology

It used to be confusing. In the 19th century in particular, the trade barriers in the small German states became apparent in the countless measures of length: Baden, for example, had 112 cubit measures and 65 different weights for a pound in use at the beginning of the 19th century. The French occupation, which introduced the metric system in the territories it occupied, was one of the factors that led to standardization in the German states. Even after the French occupiers left the regions again, the metric system was partially retained.

Although the Prussian reform of 1816 did not yet introduce the metric system, it did establish the foundations of the weights and measures offices, which were introduced in the government districts and monitored the correctness of the units using weights and measures. A commission of experts in turn supervised the offices.

The metric system slowly became established in Europe: On August 17, 1868, the North German Confederation introduced the metric system by an act of King Wilhelm II. All that was needed was one more step towards a common international basis. A scientist from Berlin played a decisive role in this: the astronomer and science journalist Wilhelm Julius Foerster became a member of the International Weights and Measures Committee in 1869. He assumed a key position in the negotiations on the Metre Convention.

Tough negotiations on the right measure

Twenty countries attended the opening of the diplomatic conference on the meter in Paris on 1 March 1875. Together with fellow scientist Adolph Hirsch, Foerster submitted a specially drafted proposal representing the German Empire, a large part of which made it into the meter convention after more than two months of tough negotiations. With their negotiating skills, they were regarded as the driving force behind the initiative for the international agreement on uniform measurement standards. Wilhelm Foerster, who promoted many other scientific initiatives, became president of the IBMG from 1891 to 1920.

Germany even has three original meters. On October 4, 1879, version 3 of the Urmeter was produced. On behalf of the French government, 30 copies were made from it, which were also made of a platinum-iridium alloy. They were raffled off among the member states, two of which found their way to Germany: Number 18 went to the Prussian Empire in Berlin, number 7 found its way to Bavaria – the copy was kept in Munich.

During the Third Reich, metrology was centralized. Number 7 also went to Berlin. During the turmoil of war, both copies were taken to Weida in Thuringia. After the war, both original meters were transferred in 1947 to the German Office for Weights and Measures (DAMG) in East Berlin, which was newly founded by the Soviet occupation zone and was comparable to the German Institute for Standardization.

Both original meters were now in the possession of the GDR, and they made no attempt to hand over one of the original meters to the West German class enemy. Instead, the Federal Republic made do by buying one from Belgium. Number 12 went to Flanders and number 23 to Wallonia. The latter was bought by the West German state in 1953. The physical original meters were binding until 1960, when it was realized that the increasingly precise measuring technology meant that a physical original meter could no longer fulfil its role.

Redefinition of the meter definition without a workpiece

Thus, in 1960, the definition of the meter was redefined at the 11th General Conference on Weights and Measures (CGPM): From then on, a meter was 1,650,763.73 times the wavelength of light emitted by a krypton-86 atom. This meant that the definition was ten times more accurate than the determination by means of the original physical meter. Thanks to technical advances in laser technology, this definition only lasted until 1983, when it was re-linked to the speed of light at the 17th General Conference on Weights and Measures. Since then, one meter has been the length of the distance that light travels in a vacuum during 1/299 792 458 of a second.

After reunification, numbers 18 and 23 went to the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig. Number 7 went back to Munich on permanent loan in 2000. In 2012, a supposedly stolen original meter from an exhibition in Weida caused a lot of excitement: on the night of May 12, 2012, thieves broke into the Osterburg and deliberately stole an original meter on display. A short time later, the all-clear was given: What the thieves appropriated was not an original copy, which would have been worth over 100,000 euros, but only a replica of the copy made of steel.
The valuable originals remained in the PTB vault. This meant that the thieves now had their own original meter. But a folding rule would probably have done as well.

(mawi)