Page:Popular Science Monthly Volume 30.djvu/260

246 larger number of states into which Europe is divided. This system is the metric system.

Aside from the fact that the metric or decimal system permits of all sorts of calculations being made more quickly and easily, it possesses as its foundation a basis which is thoroughly scientific. The other systems of measurement are based on a more or less arbitrary standard, which may be indestructible, but which is liable to alter like anything made by the hands of mortal. But the basis on which the metric system rests can be supposed to be unalterable, being the earth itself as measured by the length of its meridian. The standard of unit in the metric system is the metre, the length of which is the part of the quadrant, or the  part of the whole meridian. In order, therefore, to obtain the exact length of the metre, it was necessary to measure an arc of meridian of sufficient length to guarantee the exact calculation of the whole meridian. This arc, which had a length of nearly ten degrees, was measured between Dunkerque and Barcelona, the most prominent mathematicians of the time in France being intrusted with the execution. Although the greatest possible accuracy obtainable at that time was secured, the method of execution was not so perfect as those now in use. The metallic thermometer, invented by Borda, and which is described further on in the base measurement, was then used for the first time, but, instead of iron and zinc, the metals used were platinum and copper.

This arc was later on extended from Barcelona southward as far as the Balearic Isles by Arago and other French observers, who ran their net southward through Spain, and measured some very large triangles between the continent and the islands.

In all European countries geodetical measurements were made during the first half of the present century. To combine all these different lines measured by uniting them by means of special chains of triangles, and so obtain series of uninterrupted observations over a comparatively large area, was the work undertaken by Bessel in Prussia. This work possesses a high scientific and historical value on account of the thoroughness with which it was executed, and because the methods of execution then applied have become standard and have been accepted and imitated in modern geodesy. The geographical position of Prussia rendered the triangulation there of special importance as a means of connection between the different lines measured in the countries north and south, east and west of Prussia. This work was begun in 1831, and a connection was made between the French and Russian triangulations, and between the Danish and the South German nets.

Continental Europe has always taken the first place as the home of science; and scientific work, of whatever kind, can not fail to be duly appreciated there and to obtain that encouragement it necessarily needs. But Europe is politically so divided that the various states, however populous and powerful, are comparatively small in extent. For the