1894.] on Destructive Effects of Projectiles. 233 



because, in spite of the plausible papers of Hagenbach and Socin, 

 there are certain facts plain and simple enough which, to my mind, 

 completely dispose of the notion put forward by those authors, 

 namely, that the bullet undergoing deformation on striking a hard 

 substance like bone becomes heated so intensely that it partly fuses. 

 The simplest observation of all is that, I think, made by Yon Beck, 

 and which I have often confirmed, namely that a bullet, though com- 

 pletely deformed by impact, may enclose a hair or piece of wood 

 without these being in the least degree altered by heat ; while as for 

 its being heated in the barrel, &c, that cannot amount to 40 C, for 

 Messner has shown that a bullet traversing dirty clothing carries 

 with it living microbes, and deposits them in the object it strikes, 

 still in a living state, so that they grow therein if the soil is a suit- 

 able one ; and these observations have been fully confirmed by 

 Delorme and Laveran. It is to bo hoped that we have heard the last 

 of this unquestionably exaggerated idea of the heating of a bullet. 



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



We now enter upon the discussion of the most interesting of all 

 the physical considerations determining the well-known bursting 

 effect which a bullet produces on certain substances, e.g. clay, brain, 

 &c, while simply perforating others, e.g. wood, iron, &c. The reason 

 why a bullet behaves apparently quite differently when it is forcing 

 its way through solids of different kinds, has been, as a matter of fact, 

 answered ever since 1848, when Huguier made some remarkable, but 

 little known, researches on the effects of bullets on soft tissues, after 

 he had observed the results of the wounds inflicted in the fighting in 

 Paris in 1848. It will be remembered that in that struggle, as in 

 others, the appearance of bursting within the tissues was very note- 

 worthy, and gave rise to the notion of explosive bullets having been 

 employed by the combatants contrary to the received opinions of 

 international comity. The whole question is a perfectly simple 

 matter, and resolves itself merely into the proposition that destructive 

 effects vary in direct proportion to the cohesiveness, i.e. the fluidity 

 of the particles composing the body. Ever since the observations of 

 Tresca, Roberts- Austen and others, we have been made familiar with 

 the phenomenon of the flow of metals when these are subjected to 

 powerful pressure, and the mode of the displacement of the particles 

 has always been compared to the displacement observed in viscous 

 fluids. The extreme case in which fluidity is least present is that of 

 the substances which we term brittle. In these, while much pulveri- 

 sation occurs, the displacement of particles laterally is very slightly 

 marked. Contrast the penetration of an example of this class, namely 

 a flat, thin bone, with the effect produced on a more or less plastic 

 solid like brain, and a striking difference presents itself, for whereas 

 the bone is simply penetrated in the long axis of the bullet, the brain 

 is thrown aside in every direction. Huguier made observations on 

 certain dead organs, e.g. lung, liver, &c, and suggested that the reason 

 why there was so much lateral disturbance was that the tissues con- 

 Vol. XIV. (No. 88.) r 



