58 ©N THE FIRE-DAMP OF COAL-MINES, 



firing the gas as it collects, by a lamp of a particular construc- 

 tion, suspended nigh the roof. This would be safer than the 

 old method, by which the workmen are sometimes injured, and 

 which, whenever the production of the gas becomes consider- 

 able, is evidently impracticable. But the exhausting machine 

 noticed in the text, (page 45.) may always be -applied with suf- 

 ficient effect, and where the gas is slowly collected, must be 

 preferable to any other method, where a current of air cannot 

 be completely established. In the Hurlet mine, near Paisley, 

 it has been employed with entire success, and on so small a 

 scale, that it is worked with a hand pump. The cylinder ex- 

 hausting the air is 23 inches in diameter, and it makes a 13 

 inch stroke 13 times per minute ; it discharges, therefore, in 

 that time, 40 cubic feet of air. It is worked by a boy, and on- 

 ly as it is required. Tubes of tinned iron are connected with 

 it, which are prolonged as the excavation extends. 



Description of the Figures. (Page 36.) 



Fig. 1. Plate 1. represents the Fixed Lamp. 



A, The glass case within which the candle or lamp is placed 



in a socket, with the aperture at the top, of a sufficient 

 size to admit of the escape of the smoke and heated air. 



B, The tube of tinned iron, or of copper, which enters beneath 



the socket, conveying air from the floor to support the 

 flame. To shew the length, it is represented in two parts, 

 and at the under extremity it is turned up to the height 

 of three inches, to attain the advantages explained, p. 52. 



Fig. 



