The sub-officers are selected from the cavalry corps--one from every two regiments of cavalry and artillery, and every two squadrons of the park-trains and military equipages. The non-commissioned officers are chosen annually by the inspectors-general--one from each regiment of cavalry:--from among those that show a peculiar aptness for equitation and are distinguished by good conduct, information, zeal, and intelligence; those who are recommended for promotion in their corps are selected in preference. Their age must not exceed twenty-five years, and they must have served at least one year in the ranks. These pupils, numbering about four hundred, are sent to the school by order of the Minister of War. They continue connected with their corps, from which they are regarded as detached while they remain at the school. They receive additional pay. Those who after due trial are found deficient in the necessary qualifications, are sent back to their regiments. Upon the recommendation of the inspector-general of the school, the officers who are serving as pupils, compete for promotion by choice with the officers of the corps from which they are detached. The cavalry lieutenant, who graduates first in his class, is presented for the first vacancy as captain-instructor that occurs in the cavalry, provided he has the seniority of rank required by law. The lieutenant who graduates second obtains, under the same condition, the second vacancy of captain-instructor, provided his division consisted of more than thirty members. The sub-lieutenant graduating first, provided he is not lower than the tenth in the general classification of the officers of both grades, is presented for promotion to the first vacant lieutenancy that occurs in his regiment. The non-commissioned officers who pass a satisfactory final examination, are immediately promoted to vacancies that have been preserved for them in their regiments--those who have graduated among the first ten of the class, being presented for promotion as sub-lieutenants, as soon as they have completed their required term of service as non-commissioned officers. Those who attend the school as non-commissioned officers, frequently return as officers for instruction, and again in a higher grade on the staff of the school. Officers transferred from the infantry to the cavalry are generally sent to this school for a short time at least. The captains-instructor of the cavalry regiments, and the instructors of equitation in the artillery regiments, are mostly selected from the graduates.