‘™ 
58 ON 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. 
