540 KEPORT — 1894. 



This is 110 doubt true, but it is not true of the base of the bore, which 

 in modern guns is almost invariably a movable piece, and which under 

 certain circumstances might have to sustain the full force of the violent 

 pressures, a sample of which I have cited. 



To ascertain the mean pressure throughout the bore it seems to me 

 that there is no method so satisfactory, despite its attendant labour, as 

 that of making the projectile write its own story. In that case we cannot 

 fall into the error of making the pressures three or four times as great as 

 are necessary to generate the energy the projectile has actually acquired, 

 while occasional errors, due to causes I have not time to explain, are 

 easily detected and eliminated. 



To give an idea of how great is the range of velocity over wliich these 

 experiments have been carried, I exhibit here diagrams (tigs. 9 and 10) show- 

 ing the velocities and pressures obtained with several of the new explosives 

 which in recent years have attracted so much attention. Observe also how 

 closely, with the exception of the one somewhat brisante powder, the 

 results given by the chronoscope accord with those given by the crusher 

 gauge. Where these differ, as I have elsewhere pointed out, the two modes 

 of research so widely different are complementary to each other. 



The chronoscope takes little or no note of the violent oscillations of 

 pressure acting during exceedingly minute intervals of time. On the 

 other hand, if with the explosives I allude to we trusted to the indications 

 of the crusher gauge, we should arrive at a most erroneous idea of the 

 energy communicated to the projectile. 



In concluding, if I may venture to quote the excuse of a much more 

 eminent man than myself, I have only to express my regret that I have not 

 had time to condense the remarks with which I fear I have fatigued you, 

 while at the same time I am aware that there are many important points 

 in connection with my subject which I have left altogether untouched, 

 and others upon which I have touched that require further elucidation. 



