482 Intelligence and Miscellaneous Articles, 



*s disengaged and is collected in the graduated tube is at least a 

 hundred times as great as the volume of the projectile. 



These experiments appear to me to prove that sufficient attention 

 has not been devoted to the important part which air plays in the 

 penetration of projectiles into resisting media, and during their 

 passage through more or less thick solid plates. 



I have made an extensive series of shots in plates of different 

 kinds, using projectiles either of metal or of organic substances, as 

 stearine, wood, caoutchouc, &c, varying the nature of the media to 

 be penetrated and the substance of the projectile. 



The following are some facts. 



If a leaden ball be fired either with a great or a small velocity at 

 an ordinary slate, the projectile traverses without smashing it; the 

 round apertures produced are small, and but little different whatever 

 be the velocity. A perfectly round hole may even be made, without 

 breaking the slate, although the velocity of the projectile is inadequate 

 to pass through the slate. This latter experiment requires that the 

 slate be fastened in a wooden frame, or regularly supported in several 

 points. If a lead or a cast-iron ball be fired from a pistol or a gun 

 against a leaden plate, it is observed that the larger apertures in the 

 lead correspond to the great velocities, so that the measurement 

 of the diameter would furnish a datum for the velocity of the 

 projectile. The plate remains flat for great velocities, but bulges 

 out with small ones. Chipped edges are produced on the two sides 

 of the plate : those on the side of the face struck are virtually per- 

 pendicular to the trajectory, those on the opposite face are parallel; 

 in short, they are almost at right angles. 



The results of the firing into plates of plastic clay are of the most 

 unexpected character, and have surprised all the artillery officers 

 who have witnessed them. 



(1) With equal velocities the apertures are larger the thicker the 

 plates traversed, up to a certain limit. 



(2) The diameter of the circular apertures increases with the velo- 

 locity of the projectile. 



Thus a pistol-bullet (12 millims. in diameter and weighing about 

 10 grammes) produces in a very plastic plate of ordinary clay, when 

 shot by a charge of powder of 0'150 gr., an aperture having twice the 

 diameter of the ball; the same projectile shot by 2 to 2*5 grins, 

 of powder produces such an aperture as would be attributed to a 

 projectile from a field-gun. 



The edges on both sides are so strongly jagged that it is difficult 

 to say on which side of the plate the ball has struck. 



This phenomenon is accompanied by one no less remarkable : part 

 of the clay flies towards the firer, and is thrown several metres in the 

 opposite direction to that of the projectile. 



(3) Two plates of clay are taken, each about 15 millims. thick and 

 25 to 30 centimetres in diameter, and are cemented together by 

 moistening their surfaces. 



If a pistol-bullet be shot by 2 grms. of powder against these plates, 

 the edges are formed as in the preceding experiment; but the two 



