488 



Prof. F. Clowes. 

 FIG. 1. 



[Feb. 2, 



ferred. The cylinder is made of hydraulic steel tube ; it is 5 inches 

 in length by 1 inch in diameter, and barely exceeds 1 Ib. in weight. 

 It can be instantaneously attached to the lamp by a quarter turn ; a 

 clip arrangement then holds it firmly at both ends ; it is as quickly 

 detachable. When the cylinder is not attached, the lamp is an 

 ordinary safety-lamp. The cylinder, when attached, forms a most 

 convenient strong and rigid handle at the side of the lamp, by which 

 the lamp may be supported in the left hand while the hydrogen flame 

 is being adjusted by the right. The whole process of passing from 

 the bright flame to the hydrogen flame and back again to the bright 

 flame, including a hydrogen-flame test, is easily effected in thirty 

 seconds. The process of testing is precisely that described above for 

 the cylinder with flexible lamp connexion. 



The little cylinder is charged with hydrogen by connecting it with 

 a larger store cylinder of the gas under a compression which may vary 

 between 120 and 60 atmospheres. When charged at 100 atmospheres 

 pressure, it furnished the standard 10-mm. flame, burning continuously, 

 for about 40 minutes. This would be an ample supply of hydrogen 

 for one inspection of a mine, since the hydrogen flame would only be 

 used occasionally, and then for very short intervals only. If a longer 

 service is required, a cylinder of the same diameter, but of greater 

 length, and of capacity half as great again, may be adapted to the 

 lamp. Or one or more reserve cylinders can be easily carried in the 

 pocket. The small cylinder may be charged sufficiently for use 

 several hundred times from a large cylinder under 120 atmospheres- 

 pressure. 



