The war depot has taken a large share in the preparation of the map of France. The first idea of undertaking this important work dates from 1808. After various delays and difficulties, the trigonometrical survey, which had been for a time suspended, was recommenced in 1818. The work was placed under the war depot, intrusted to the corps of geographical engineers. Since this period the geographical engineers have been incorporated in the staff corps, by the officers of which the work has been continued. The primary triangulation was finished in 1845; the secondary is now finished; the filling in the details will occupy several years to come. The number of officers of the staff corps employed on the survey has varied from twenty-six to ninety. THE STAFF CORPS. The officers of the French staff constitute a distinct and separate corps, numbering thirty-five colonels, thirty-five lieutenant-colonels, one hundred and ten majors, three hundred and thirty captains, and one hundred lieutenants. None but officers of this corps can be employed on the staff. When, by accident, there is not a sufficient number present, regimental officers may be temporarily employed, but they return to their regiments as soon as officers of the staff corps arrive to replace them. The division of the staff into adjutant-general’s and quartermaster-general’s department does not exist in the French service. The only means of entering the staff corps is through the Staff School of Application. Of the fifty student-officers which the School of Application usually contains, twenty-five leave annually to enter the staff corps, and are replaced by an equal number. Three of these come from the Polytechnic, the remaining twenty-two are selected from thirty pupils of the Military School of St. Cyr, who compete with thirty second lieutenants of the army, if so many present themselves; but, in general, the number of the latter does not exceed four or five. The course of study in the Staff School of Application lasts two years. The students have the rank of second lieutenant. On passing the final examination they are promoted to the rank of lieutenant; they are then sent to the infantry to do duty for _two years_, at the expiration of which time they are attached for an equal period to the cavalry. They may finally be sent for a year to the artillery or engineers. This routine can not be interrupted except in time of war, and even then the lieutenant can not be employed on staff duty until he has completed his _two years_ with the infantry. However, officers who have a special aptitude for the science of geodesy or topography, may even earlier be employed on the map of France or other similar duty; and, further, two of the lieutenants, immediately on quitting the Staff School of Application, are sent to the war depot (_Dépôt de la Guerre_) to gain a familiarity with trigonometrical operations.