1894.] on Destructive Effects of Projectiles. 235 



that the separation of the bones is most marked on the side of the 

 entry of the bullet. It was the observation of this latter point which 

 led me to think that it might be possible to automatically record 

 the disturbance of the fluid, and this was effected in the following 

 way. 



A long trough having been prepared, with one end closed with 

 rubber one-eighth of an inch thick, and a tall, white, flat surface 

 lowered vertically into the trough, the latter is filled with a solution 

 of methylene blue. A small bullet of low velocity (600 feet per 

 second) is fired in the long axis of the trough, 1 cm. below the surface 

 of the water. As a result, a wave is thrown up against the white 

 screen, which is consequently marked with a blue splash, the same 

 describing a curve indicating, firstly, that the disturbance is greatest 

 where the velocity and resistance, increased by compression, are both 

 at their highest, i.e. soon after the bullet enters the fluid ; and 

 secondly, that the displacement diminishes gradually as the momentum 

 lessens. 



Complete confirmation of the parallelism between soft solids and 

 fluids in their behaviour to the rapidly-moving bullet, is seen in 

 comparing the cast of the track made by a bullet moving through 

 clay with the curves obtained by the water record. 



In both the maximal displacement occurs shortly after the bullet 

 has entered the substance, and in both the diminution of disturbance 

 is much more gradual than its development, and is evidently propor- 

 tional in the main to the loss of momentum. A final proof is afforded 

 by suspending columns of methylene blue in clear water or salt 

 solution, and then firing through the whole. With the '380 bullet 

 and three grains of smokeless powder the last column in the 4-foot 

 trough was not disturbed. 



This, doubtless, is a result which would be generally foreseen, but 

 it was worth while to test it experimentally, and it certainly very 

 strikingly demonstrates how localised the bursting disturbance is, 

 which completely explains the limitation of the explosive effect on 

 the skull on the side of entry. Sundry interesting subordinate points 

 arose in the course of these experiments, and have served to afford 

 the necessary control of the method, e.g. the peculiar splash of the 

 bullet striking the rubber end of the trough alone, i.e. not pene- 

 trating ; and, again, the tracing made by a bullet which, being fired 

 a little too superficially, records the elevation of successive waves as 

 it ricochets along the surface ; and, finally, the record of a bullet 

 deflected by the resistance of the water (as well as by want of 

 horizon tality, showing a long, oblique splash where it has carried up 

 the fluid into the air. 



From all these experiments on the pure physics of this subject we 

 are justified in believing that when a bullet is fired against the head 

 (whether that of a man or any other warm-blooded animal), so as to 

 penetrate the cerebral hemispheres in a transverse direction, the 

 following series of phenomena occurs. The impact of the bullet on 



r 2 



