20 Mr. Bevan Lean and Mr. H. R. Dixon on 



(2) TS = 2i5 mm. Vol. of air-gap 53 , 6cc. 



B not fired by explosion in A. 



6 concordant experiments made. (May 6). 



On May 9 the experiment was repeated, employing the 

 same glass tube, the same mixture of hydrogen and 

 oxygen, TS being 215 mm., as before. In 4 suc- 

 cessive experiments B was fired by the explosion 

 in A, but in two of these the glass tube DF ex- 

 ploded with great violence, and in the other 

 two the cement at one or other junction was 

 cracked. Thus, in these four experiments, in 

 which B was fired, the pressure in the apparatus 

 was relieved; since, therefore, it seemed conceivable 

 that in cases in which the limit had been nearly 

 reached, such relief of the pressure might enable A 

 to fire B across the air-gap, it appeared advisable in 

 future experiments only to accept as conclusive 

 those in which every junction had stood intact the 

 shock of the explosion. 



4 more experiments were made, in which the apparatus 



successfully stood the explosion, and in each case 

 B was not fired. 



(3) TS = i75 mm. Vol. of air-gap, 38*2 cc. 



B fired by explosion in A. 

 3 experiments made, May 9. 



5 experiments made, May 12. 



Thus the desired limit is to be found when TS lies, 

 between 215 and 175 mm. 



(4) TS = 205 mm. Vol. of air-gap, 48*5 cc. 



B not fired by explosions in A. 



2 experiments made — cement intact. 



(5)TS=i84mm. Air-gap = 40 cc. 

 B fired. 2 experiments. 



(6) TS=i92 mm. Air-gap = 43 cc. 



B fired. 2 experiments. 



(7) TS=i96 mm. Air-gap = 44"7 cc. 



B not fired. 3 experiments. 



Thus the limit is to be found between (6) and (7.) 



