0 
moment the corresponding pressure, and reconstitute afterwards the law of 
development of the pressure in functions of the time up to the moment of the 
maximum pressure. The apparatus constitutes therefore a real registering pres¬ 
sure-gauge. 
The knowledge of the law of development of the pressures in functions of the 
time leads naturally to a knowledge of the velocities and of the movements of 
the projectile in the bore in functions also of the time. 
2°—The crusher apparatus placed in front of the driving ring of the projec¬ 
tile works dynamically, as theory led us to expect. 
The trials carried out in the 5"* 5 naval gun, with the crusher bolt placed a 
few centimetres in front of the ring, have clearly shown this complete change in 
the mode of working of the crusher apparatus, as shown by an examination of the 
tracings obtained in two identical rounds by means of the same apparatus, placed 
successively, in the powder chamber, and in front of the driving ring of the 
projectile. 
The compressions observed were 0*0528 inches in the powder chamber, and 
0*1024 inches in front of the ring. The compression in the powder chamber 
was effected with comparative slowness in a duration of 12 vibrations of a tun¬ 
ing fork, about *003 of a second. 
The compression produced by the sudden application of the pressure, after 
the projectile had unmasked the orifice of the crusher placed in front of its 
ring, was effected in a time inferior to the duration of a half vibration of the 
vibrating lever. This duration of time, about *00025 of a second, is very 
near that assigned by theory to the dynamic compression of a cylinder by an 
ounce piston. In this case, theory indicates that the compression is double that 
which would correspond to the pressure to which the apparatus was subjec¬ 
ted if that pressure were exerted statically, which is in conformity with the 
experimental result. 
3°—The first researches undertaken by aid of these instruments have also 
shown clearly the anomalies which characterise the burning of powders in the 
bores of guns, anomalies which a mere observation of the maximum pressures 
gave no cause to suspect. These researches have led to a knowledge of the 
conditions under which the anomalies in the distribution of the pressures may be 
eliminated. 
