Besides this, for those cannon and howitzers which have dolphins, a transverse section taken across the middle of the dolphins and the axis of the trunnions. For mortars, a transverse section made by a plane passing in front of the dolphins, the whole on a scale of one-fifth. 2. Detail of the button (comprising the cascable and breeching loop for naval ordnance) on a scale of two-fifths. 3. Detail of the tracing of a dolphin, on the scale of two-fifths. 4. Tracing of the bush of a gun, on a scale of two-fifths, and tracing of a priming-pan at the real size. 5. For garrison ordnance, in cast-iron, detail of the widening of the base ring on a scale of two-fifths. 6. Tracing of a cannon-ball, of a howitzer-shell, and of a shell, on a scale of one-fifth. Tracing of the lugs of a shell, ring and lug at the real size. All the parts of the drawing must be colored in uniform tints in conformity to the table of conventional colors; the annexation of the figures of measurement is not required. This work is preceded by three or four lectures intended to make the students familiar with the tracings which they have to execute, and the solution of the problems in geometry and descriptive geometry, to which the representation on paper of pieces of ordnance and their projectiles give rise. II. DESIGN FOR ORDNANCE (24 DAYS.) The design for ordnance has for its object the complete determination of the nature of a projectile, and of a piece of ordnance in accordance with certain special conditions, inquiring into the laws of the motion of the projectile, and into its principal destructive effects, and the settlement of practice-tables for the gun. The general case for treatment is that of a howitzer, which comprehends the gun and the mortar as particular cases. The data usually adopted are,-- 1. For the projectile, its weight and the quantity of powder which it is capable of containing. 2. For the piece, the initial velocity of its projectile. This operation comprises calculations, a drawing, and a memoir. The drawing, on colombier paper, which must be figured in all its parts, contains,-- 1. The tracing of the profile of the piece, as it is determined by calculation, so as to satisfy the different conditions of resistance, on a scale of one-fifth. 2. The complete tracing of the piece executed in conformity with the rules laid down for the tracing of ordnance on a scale of one-fifth. 3. Tracing of the projectile on a scale of one-fifth. 4. Tracing of the wooden bottom and of the fuse of the projectile, executed in the case of each of these objects in two figures--the one on a large scale (two-thirds, or even the size of nature,) representing the inquiry into their forms and dimensions, the other giving on a scale of one-fifth the results of this inquiry. To this is added, for the mountain howitzer, or any other howitzer for which it is admissible, a tracing of the mounted howitzer carriage.