254 THE POPULAR SCIENCE MONTHLY. 



the surrounding States, in all forty-seven stations. They are all first- 

 class stations. To show how slow geodetical triangulation has neces- 

 sarily to be, it may be stated that in the small State of New Jersey 

 alone this work has been going on for nearly thirteen years, and is 

 now nearly completed, only a few stations remaining to be covered at 

 the beginning of the year 1886. 



I may here state also that a few of the historical facts I have given 

 are taken from "Elements of Geodesy," by J. Howard Gore, B. S., just 

 published. 



The idea of connecting the various measurements in the different 

 European states was later on improved upon, and for the purpose of 

 obtaining good, reliable data, collected on a system of uniformity suffi- 

 ciently numerous and covering a large area of territory, all the states 

 of Continental Europe have combined in the interest of science. If 

 each country did its work separately, and the data obtained in one 

 could not be compared with others, the observations made would have 

 only a local value, and, being limited in extent, could not have that 

 scientific weight which it is necessary they should have. All European 

 countries have felt the necessity of having thorough topographical sur- 

 veys made, so as to possess good, detailed maps of their territory. This 

 work being considered necessary for military purposes, its execution 

 has been undertaken by the military authorities. The triangulation 

 work necessary for this purpose could, with little addition, be extended 

 so as to connect the geodetical nets of the various countries and form 

 a complete system of nets extending over the whole continent. An 

 agreement was entered into, by the various states into which Europe 

 is divided, that the geodetic data which were being collected and the 

 observations that were being made should become common property, 

 and that all the observations being made on a standard of uniformity 

 agreed upon by all parties concerned, they should be used in common 

 for the purpose of furthering the scientific problem and obtaining a 

 series of nets, by means of which the exact distance between any two 

 points on the European Continent could be easily calculated. 



The common work — that is, the direction of the whole as an inter- 

 national undertaking, each country doing its own share within its own 

 borders — has been confided to an international commission specially 

 founded for the purpose, and which is known as the Commission In- 

 ternationale pour la Mesure du Degre en Europe. All the states are 

 represented in this commission, the representatives being mostly the 

 heads of the geodetical department of each country, and some of the 

 best-known astronomers. The best specialists of Europe, who have 

 devoted their life to this branch of studies, belong to this com- 

 mission. 



The international agreement makes it possible to have uninter- 

 rupted chains of triangles across the whole continent, from north to 

 south, and from east to west. It is, however, not necessary that the 



