8th. At the points of intersection of the profiles with the projections of the ridges of the works, as well as at the points used for adjusting, poles or pickets are placed, on which the points belonging to the ridges are marked. These points will be joined together in each profile by twine, indicating the different planes of the work. 9th. The form and dimensions of the batteries, either of barbettes or embrasures, will be equally determined by poles or pickets placed at all their angles, and united together by twine in the manner that will be subsequently explained. 10th. For the barbette batteries, the first thing to be done is to establish and to construct the front coupé of the salient of the interior crest, and substitute an interior horizontal crest throughout the extent of the barbette for that situated in the plane of defilement. The necessary adjustments are then made between the slope of the parapet of the barbette and that of the rest of the face, and indicate by means of twine the intersections of the terre-plein of the barbette and of its slope with the different planes of the work. 11th. For the embrasures, after having determined their direction, the intersections of the cheeks and bottom, with the interior and exterior slope of the parapet, and with its slope; also the slope which terminates the interruption of the banquette throughout the extent of the battery. In the case where the platform is formed more than 0^m 4 elevated above the soil, a ramp is constructed with its slope, and the intersections with the slope from the platform are shown. 12th. After the batteries, the slope of the ends of the traverses and of the passages for entry and exit are constructed. 13th. The traverse will be finished by adjusting its different planes with those of the parapet. In the particular case, where it was interfered with to make a passage over the banquette, it is finished by reveting the slope passing by the crest of the banquette of the work. 14th. At the passages of entry and exit from the work, the parapets will be finished by the slope of the revetment, whose intersections with the different planes of the parapets must be determined. 15th. For each squad of workmen, the distance of the salient of the work to the point on which it will be defiladed must be determined. MEMOIR. 1st. Object of defilement--which is considered to be dangerous ground, dangerous point, plane of defilement. 2d. Position of the dangerous point relatively to the work which is to be defiladed. Practical method on the ground. Results to which it leads. 3d. On the field this method is not always applicable to an isolated work, and never is so to entrenchments of a great development, such as lines, large têtes-de-pont, &c. By what proceeding is it generally expedient to attempt to fulfill in war the indisputable condition of defilement. RECAPITULATION FOR THE SUB-LIEUTENANTS OF ARTILLERY AND ENGINEERS.