The duties of the chief of the staff are to transmit the orders of the general; to execute those which he receives from him personally, for field-works, pitching camps, reconnaissances, visits of posts, &c.; to correspond with the commanding officers of the artillery and the engineers, and with the commissariat, in order to keep the general exactly informed of the state of the different branches of the service; to be constantly in communication with the different corps, so as to be perfectly master of everything relating to them; to prepare for the commander-in-chief and for the minister of war, returns of the strength and position of the different corps and detachments, reports on marches and operations, and, in short, every necessary information. The distribution of the other officers of different ranks, when it has not been made by the minister of war, is regulated by the chief of the general staff. In every division of the army an officer of the staff is specially charged with the office work; the others assist him when necessary, but they are more usually employed in general staff duties, in reconnaissances, drawing plans of ground, missions, the arrangement of camps and cantonments, superintending the distribution of the rations, &c. The officers of the staff may further be charged with the direction of field-works thrown up to cover camps and cantonments. Staff officers of all ranks may be employed on posts and detachments. On special missions they command all other officers of the same rank employed with them. When a staff officer is charged with the direction of an expedition or a reconnaissance, without having the command of the troops, the officer in command concerts with him in all the dispositions it may be necessary to make to ensure the success of the operation. The staff of generals of artillery and of engineers is composed of officers of their respective arms. The war depot (_Dépôt de la Guerre_) was founded for the purpose of collecting and preserving military historical papers, reconnaissances, memoirs, and plans of battles; to preserve plans and MSS. maps useful for military purposes, and to have them copied and published. It is divided into two sections--one charged with trigonometrical surveying, topography, plan drawing, and engraving; the other with historical composition, military statistics, the care of the library, the archives, plans, and maps. Each of these sections is under the direction of a colonel of the staff corps, who has under his orders several officers of his corps.