the surrounding States, in all forty-seven stations. They are all first-class stations. To show how slow geodetical triangulation has necessarily 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 sufficiently 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 surveys 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 international 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 Internationale pour la Mesure du Degré 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 commission.
The international agreement makes it possible to have uninterrupted chains of triangles across the whole continent, from north to south, and from east to west. It is, however, not necessary that the