1894.] on Destructive Effects of Projectiles. 231 



concerned, that for a unit, say one inch, of the flight of the bullet would 

 be extremely small, namely about one-twentieth of the circumference 

 of the bullet, which roughly speaking, would be (for the ■ 380 bullet) 

 about one-twentieth of an inch, the insignificance of which is obvious. 

 The matter, however, assumes a somewhat different aspect when a 

 bullet is engaged in a solid substance through which it is forcing its 

 way with rapidly diminishing velocity. In such a case, where the 

 projection journey of the projectile is quickly coming to an end, it 

 becomes of special importance to see what is becoming of the factor of 

 rotation. The plaster casts obtained in the manner indicated show 

 clearly enough the interesting fact that the rotation persists to the 

 end, when the bullet has simply taken its course through the atmo- 

 sphere and then entered the soft clay. Further, the casts also show 

 what is a necessary deduction from our earlier considerations on this 

 matter, namely, that as the rotation is preserved till the end of the 

 trajectory, the twist is proportionately more pronounced as the forward 

 movement is lost. 



It is for our present purpose important to see whether the rotation 

 is well marked when the projectile is completely deformed. To 

 examine this point a new series of experiments was undertaken, in 

 which the bullet was first caused to penetrate a flat bone before 

 entering the clay. It is very clear that the rotation is still present. 

 In discussing this question I have left unnoticed the fact that owing 

 to the resistance of a body like clay, the cohesiveness of which of 

 necessity varies slightly from point to point, there will be a great 

 tendency for the bullet to change its direction, more especially as the 

 base is heavier than the apex, and to this change of direction must be 

 attributed in part the change of surface simulating the rotation effects 

 due to the rifling. The two conditions, however, can be distinguished 

 readily on careful examination. 



So far as destructive effects in the brain are concerned, it is 

 therefore clear that relatively little is to be ascribed to rotation. 



Projection Destructive Effects. — The destruction by the bullet 

 moving forward through a solid body is the most important matter 

 for us to consider. There are two sets of factors determining the 

 degree of destruction in any given substance. 



1. Factors due to the bullet. 



2. Factors due to the physical constitution of the solid. 



1. Factors due to the bullet. So far as the projectile is concerned, 

 the chief considerations are (a) its momentum ; (b) its sectional area ; 

 (c) its becoming heated. 



(a) Momentum. — Although it will of course be generally under- 

 stood the greater the velocity the greater the damage for the same 

 weight of shot, still, in connection with the small-bore service rifles 

 of the present day, some seem to think that the small bullet, by virtue 

 of its travelling at a great pace, would pierce the tissues without 

 causing much general damage. The fallacy involved in this belief 

 we shall see directly ; but a single glance at the casts arranged in 



