

INFLUENCE OF DETONATORS. 99 



rapidly than sound in the same gases, taken at the ordinary 

 temperature. The condensation of the aqueous vapour, which 

 is effected behind the flame, is also of little importance, since 

 the time is too short to allow of its taking place to any 

 appreciable extent. 



Influence of the Detonators. Do the minute detonators, em- 

 ployed for interrupting the electric current of the registering 

 apparatus, help to regulate the propagation of the inflammation ? 

 In order to answer this question, it was sufficient to measure, not 

 the time that elapsed between the destruction of two fulminate 

 interrupters, placed at opposite extremities of the tube, but the 

 interval between the breaking of the induction current of the 

 coil that produced the spark at the beginning of the tube and 

 the ignition of the fulminate interrupter placed at the farthest 

 end of it. 



The intervals of time observed, for a length of 40*054 metres, 

 were 



012556, -012288, '012904 sees. 

 Mean = -012583 sees. 



But there are errors in these figures, arising from delays in 

 the registration, delays unequal in principle, as two different 

 kinds of signals are involved. The difference between these 

 two delays was calculated by measuring the time that elapsed 

 between the signal of the spark and that of an interrupter 

 05 metre away. This time is negative, i.e. the delay in the 

 signal of the spark is greater than that in the signal of the 

 interrupter. Three experiments gave 



001559, -001968, -002129 sec. 

 Mean = -001885 sec. 



This correction, added to the above experiments, gives 

 "014468 sees., bringing the velocity to 2770 metres per second. 

 The experiment made with two similar interrupters gave 

 2810 metres, the agreement of which result shows that the 

 velocity observed is independent of the detonators. 



This is still more clearly shown in some experiments here- 

 after described (p. 108), in which the propagation of the pressures 

 had been registered by effecting the initial ignition by means of 

 an electric spark. In fact, the propagation of the pressures 

 starting a few centimetres from the beginning of the tube 

 proceeds with a velocity of about 2700 metres, a rate in accord- 

 ance with the results above mentioned. 



Length of the Tube. It now remained to ascertain whether 

 the propagation of the explosion takes place uniformly in 

 the tubes. This is clearly proved in the following experi- 

 ments. 



With the caoutchouc tube 5 mms. in diameter these results 

 were obtained 



H2 



