TIME AND SPACE 287 



method he measured the distance between Alkmaar and Bergen-op- 

 Zoom, using thirty-three triangles. He obtained nearly the same results 

 with Fernel as to the circumference of the earth. Since that time sim- 

 ilar work has been going on almost uninterruptedly. In 1669 Picard 

 measured the meridian Amiens— Malvoisine, and from it estimated tlie 

 circumference of the earth to be 20,541,500 toises or fathoms. Picard's 

 figures were used by Newton in the studies which led to the discovery 

 of the universal law of gravitation. At this point in the investigations 

 the question arose whether the earth is a perfect sphere or a spheroid. 

 In order to solve this problem two expeditions were fitted out, the one 

 to operate in Peru, the other in Lapland. Both occupied several years, 

 completing their labors about 1740. The results obtained settled for all 

 time the relation of the polar to the equatorial axis. Geodetic sur- 

 veys are, however, still in progress. The most extensive of the older 

 projects was completed by Arago and Biot in 1808, based on the labors 

 of Mechain and Delambre. The meridian measured was that between 

 Dunkirk and Formentera, an island near the Mediterranean coast of 

 Spain. This arc extended over twelve degrees and twenty-two minutes. 

 The principal object of this survey was to establish a fixed unit of 

 linear measure for the meter, which was to be the one ten-millionth 

 part of the earth's meridian quadrant. This is the so-called metre des 

 Archives, a platinum rod deposited in Paris. Although it is now known 

 that it is not strictly correct there is no probability that it will ever be 

 changed, as it has become the foundation of the metric system. In 

 1861 general Baeyer proposed the measurement of the meridian Chris- 

 tiania-Palermo. The work was to be carried out by the European gov- 

 ernments conjointly. The proposal led to a general conference of 

 savants in Berlin in 1862. A permanent commission was organized 

 under the presidency of General Baeyer.^ Another conference was held 

 in Berlin in 1867, all the governments of Europe, except Turkey, hav- 

 ing in the interval promised cooperation. Since then meetings of the 

 commission have been held every two or three years, their object being 

 the continuation and revision of the French measurements to Algiers, 

 a complete triangulation of the Mediterranean Sea, the measurement 

 of a parallel through Central Africa from Cape Town to Upper Egypt, 

 and to take such other observations as usually fall within the scope of 

 a geodetic survey. For many years the United States government has 

 been engaged in measuring the ninety-eighth parallel which extends 

 from the southern point of Texas to the Canadian border. Strange as 

 it may seem in view of what they accomplished in several directions, 



^ The Prussian geueral Baeyer, who died in 1885 at the age of ninety-one, 

 probably devoted more years to geodesy than any other man of modern times. 

 He began his practical studies in 1816 and published his last work in 1881. 

 He cooperated with Bessel in many of his measurements and astronomical 

 observations. 



