He was then led to another plan for rectifying the path of the bullet through each instant of projection, and which was by creating at the posterior end, resistances, which should act in case the axis of the bullet did not coincide with the direction of motion, and this was carried out by cutting upon the cylindrical part, instead of one, as many circular grooves of ·28 in depth, as that cylindrical, or rather, slightly conical, part could contain. An increased precision in firing was the immediate result. (Plate 20, fig 15.) ~Shape of cannelures.~ Feeling his way most carefully, Captain Tamisier then made a great number of experiments in this direction, and perceived that it was important to render the posterior surface of the grooves as sharp as possible, so as to augment the action of the air; for these grooves lose their shape, owing to the lead, from its malleable nature, yielding under the strokes of the ramrod. ~Elongated Projectiles, whose Centres of Gravity do not correspond with Centre of Figure.~ ~Action of the air.~ Elongated projectiles, whose centres of gravity do not exactly coincide with the centre of figure, when they do not turn over, tend to preserve their axis in the primary direction which was imparted to them, in the same manner as an imperfectly feathered arrow flying with little velocity, the point of the moving body being constantly above the trajectory, and its axis making a certain angle (plate 21, fig 1) with the target to the curve. Therefore the part A.B. of the bullet being exposed to the direct action of the air’s resistance, the atmospherical fluid is compressed on the surface A.B., and rarified upon that of A.C. Hence it will be perceived that the compressed fluid supports the moving body, and prevents its descending as rapidly as would a spherical bullet, which is constructed to meet the same direct resistance from the air. This trajectory will therefore be more elongated than that of the spherical bullet in question. ~Remedied by the grooves.~ ~Cause of deviation.~ ~Remedy.~