Carlos Ibáñez e Ibáñez de Ibero


Carlos Ibáñez e Ibáñez de Ibero, 1st Marquis of Mulhacén, was a Spanish divisional general and geodesist. He represented Spain at the 1875 Conference of the Metre Convention and was the first president of the International Committee for Weights and Measures. As a forerunner geodesist and president of the International Geodetic Association, he played a leading role in the worldwide dissemination of the metric system. His activities resulted in the distribution of a platinum and iridium prototype of the metre to all States parties to the Metre Convention during the first meeting of the General Conference on Weights and Measures in 1889. These prototypes defined the metre right up until 1960.
He was born in Barcelona. According to Spanish tradition, his surname was a combination of his father's first surname, Martín Ibáñez y de Prado and of his mother's first surname, Carmen Ibáñez de Ibero y González del Río. As his parent's surnames were so similar he was often referred as Ibáñez or Ibáñez de Ibero or as Marquis of Mulhacén. When he died in Nice, he was still enrolled in the Engineer Corps of the Spanish Army. As he died around midnight, the date of his death is ambiguous, Spaniards retained 28th, and continental Europeans 29 January.

Scientific career

From the Map Commission to the Geographic and Statistical Institute in Spain

adopted the metric system in 1849. The Government was urged by the Royal Academy of Science to approve the creation of a large-scale map of Spain in 1852. The following year Ibáñez was appointed to undertake this task. All the scientific and technical material had to be created. Ibáñez and Saavedra went to Paris to supervise the production by Jean Brunner of a measuring instrument calibrated against the metre which they had devised and which they later compared with Borda's double-toise N°1 which was the main reference for measuring all geodetic bases in France and whose length was 3.8980732 metres.
In 1858 Spain's central geodetic base of triangulation was measured in Madridejos with exceptional precision for the time thanks to this instrument, which became known as the Spanish Standard. Ibáñez and his colleagues wrote a monograph which was translated into French by Aimé Laussedat. The experiment, in which the results of two methods were compared, ended a controversy between French and German geodesists about the length of geodesic triangulation bases, and empirically validated the method of General Johann Jacob Bayer, founder of the International Association of Geodesy.
The Spanish Standard was replicated in order to be used in Egypt, France and Germany. These Standards were used for some of the most important European surveys. In 1863, Ibáñez and Ismael Effendy compared the Spanish Standard with the Egyptian Standard in Madrid.
From 1865 to 1868 Ibáñez added the survey of the Balearic Islands with that of the Iberian Peninsula. For this work, he devised a new instrument, which allowed much faster measurements. In 1869, Ibáñez brought it along to Southampton where Alexander Ross Clarke was making the necessary measurements to compare the Standards of length used in the World. Finally, this second version of the appliance, called the Ibáñez apparatus, was used in Switzerland to measure the geodetic bases of Aarberg, Weinfelden and Bellinzona.
In 1870 Ibáñez founded the Spanish National Geographic Institute which he then directed until 1889. At the time it was the world's biggest geographic institute. It encompassed geodesy, general topography, leveling, cartography, statistics and the general service of weights and measures.

Measurement of the Paris meridian over the Mediterranean Sea

Copies of the Spanish standard were made for France and Germany. These standards would be used for the most important operations of European geodesy. Indeed, Louis Puissant had declared in 1836 to the French Academy of Sciences that Jean Baptiste Joseph Delambre and Pierre Méchain had committed an error in the measurement of the Paris meridian arc used for the determination of the metre. This was the reason for Antoine Yvon Villarceau checked the geodetic operations at eight points of the meridian arc. Some of the errors in the operations of Delambre and Méchain were then corrected. From 1870 to 1894, François Perrier, then Jean-Antonin-Léon Bassot proceeded to a new measurement of the French meridian arc.
In 1865 the triangulation of Spain was connected with that of Portugal and France. In 1866 at the conference of the Association of Geodesy in Neuchâtel, Ibáñez announced that Spain would collaborate in measuring the Paris meridian. In 1879 Ibáñez and François Perrier completed the junction between the geodetic network of Spain and Algeria and thus completed the measurement of the Paris meridian which extended from Shetland to the Sahara. This connection was a remarkable enterprise where triangles with a maximum length of 270 km were observed from mountain stations over the Mediterranean Sea. The Paris meridian arc was renamed West Europe-Africa Meridian-arc by Alexander Ross Clarke and Friedrich Robert Helmert. It yielded a value for the equatorial radius of the earth a = 6 377 935 metres, the ellipticity being assumed as 1/299.15. The radius of curvature of this arc is not uniform, being, in the mean, about 600 metres greater in the northern than in the southern part.

International scientific collaboration in geodesy and calls for an international standard unit of length

In 1866 Spain, represented by Ibáñez, joined the Central European Arc Measurement at the Permanent Commission meeting in Neuchâtel. In 1867 at the second General Conference of the Central European Arc Measurement held in Berlin, the question of an international standard unit of length was discussed in order to combine the measurements made in different countries to determine the size and shape of the Earth. The Conference recommended the adoption of the metre and the creation of an international metre commission, according to a preliminary discussion between Johann Jacob Baeyer, Adolphe Hirsch and Carlos Ibáñez e Ibáñez de Ibero. The French Academy of Sciences and the Bureau des Longitudes in Paris drew the attention of the French government to this issue. The Academy of St Petersburg and the English Standards Commission were in agreement with the recommendation.
In November 1869 the French government issued invitations to join this commission. Spain accepted and Ibáñez took part in the Committee of preparatory research from the first meeting of the in 1870. He was elected president of the Permanent Committee of the International Metre Commission in 1872. He represented Spain at the 1875 conference of the Metre Convention and at the first General Conference on Weights and Measures in 1889. At the first meeting of the International Committee for Weights and Measures, he was elected Chairman of the Committee, a position he held from 1875 to 1891. He received the Légion d'Honneur in recognition of his efforts to disseminate the metric system among all nations and was awarded the Poncelet Prize for his scientific contribution to metrology.
President of the Permanent Commission of the European Arc Measurement from 1874 to 1886, Ibáñez became the first president of the International Geodetic Association after the death of Johann Jacob Baeyer.
As Carlos Ibáñez e Ibáñez de Ibero stated, the International prototype metre would form the basis of the new international system of units, but it would no longer have any relation to the dimensions of the Earth that geodesists were trying to determine. It would be no more than the material representation of the unity of the system.
More over, the progresses of metrology combined with those of gravimetry through improvement of Kater's pendulum led to a new era of geodesy. If precision metrology had needed the help of geodesy, it could not continue to prosper without the help of metrology. Indeed, how to express all the measurements of terrestrial arcs as a function of a single unit, and all the determinations of the force of gravity with the pendulum, if metrology had not created a common unit, adopted and respected by all civilized nations, and if in addition one had not compared, with great precision, to the same unit all the rulers for measuring geodesic bases, and all the pendulum rods that had hitherto been used or would be used in the future? Only when this series of metrological comparisons would be finished with a probable error of a thousandth of a millimeter would geodesy be able to link the works of the different nations with one another, and then proclaim the result of the measurement of the Globe.