318 Mr, F. J. Bramwell [Feb. 27, 



gauge to a higher point than that at which it is now standing, 

 although that point, bo it remembered, is that which indicates the 

 pressure of the air in the holder. 



This simple experiment and those made in the locomotive illus- 

 trate the ram action of an elastic fluid, and the manner in which a 

 local pressure at the base of the shot may be set up when, with a 

 suitable air space, a very quick burning powder is used. But it would 

 be found if we were to apply pressure gauges, that this pressure is 

 extremely local, and as I have said, would not cause injury, because, 

 it is resisted by the strength of the ring of metal against which it 

 presses, and that ring is aided to resist it by the metal on each side 

 of this area of local effort ; which last-mentioned metal is not itself 

 subjected to the local pressure, and therefore has a surplus of strength 

 to aid its neighbour. 



I will now call your attention to Diagram (8) showing the experi- 

 ment which was made to test the value of the other suggested cause 

 of explosion, namely, an air space between the projectile and the 

 canted wad, over which wad it was assumed the point of the projectile 

 might pass, thus converting the wad into a wedge and bursting the 

 gun. All that I have to say about this experiment is that the effect 

 was absolutely nil, as was also an experiment made with a similar air 

 space, but with the wad not canted. 



With respect to the non-injurious effect of air spaces, many persons 

 have asked me, " How do you distinguish between the bursting of a 

 sporting gun from a little snow being in the barrel when the gun is 

 fired, and the bursting or non-bursting of the 38-ton gun with an air 

 space ? Are not these two states of things similar, and if the sj^orting 

 gun bursts in consequence of the air space between the charge and the 

 snow, why should not the 38-ton gun burst with its air space ? " The 

 answer is, that the sporting gun is not burst by the air space but by 

 the snow. I have here two barrels which have been purposely burst 

 in the manner I will describe to you. 



Diagram (9) shows these barrels in their burst condition. 



One of them, as you will see, is split open by a longitudinal split 

 of some length. This was effected by placing a plug of wax at the 

 point a a shown on the drawing, and firing a bullet against that plug. 

 The pressure required to put the wax instantly into motion at a 

 velocity equal to that of the bullet was, of course, infinite, but, as 

 infinite pressures cannot be obtained, a compromise was arrived at 

 between the shot and the wax. The shot retained part of its energy, 

 and moved forward at a reduced velocity ; the wax moved forward 

 with the same reduced velocity ; but as even this velocity could not 

 be obtained instantaneously and without heavy pressure, the first effect 

 of the impact, on the wax, was to cause it to expand laterally, and 

 thereby to burst the gun. 



The second barrel, you will see, has a ring bulge, which illustrates 

 very strikingly that which I have been saying as regards local pressure 

 at the base of a projectile. This ring bulge was obtained by placing 



