AND PREVENTING ITS EXPLOSION, ST 



One principal difficulty in contriving any safe mode of light- 

 ing coal-mines, must be that of having, moveable lights ; for 

 these the workmen will often find it necessary, and in ge- 

 neral will be desirous, to employ. This may be easily attain- 

 ed by connecting with the bottom of the case or lantern, a 

 flexible tube, air-tight or nearly so, which may be done by a 

 tube of prepared leather varnished j this tube being of such a 

 length as to reach nigh to the floor. The lamp can thus be 

 held in the hand, or attached to any occasional support. Fig. 2. 

 represents a lamp of this, kind. 



No danger, or scarcely any, I conceive, can arise in the use 

 of this apparatus. If the size of the upper aperture be duly 

 adjusted, no air can enter by it to the lamp, for the current of 

 heated air will prevent this. And this air can never be heated, 

 so high as to. kindle any mixture of carburetted hydrogen* 



No inflammable air can enter from the bottom, so as to be- 

 capable of kindling, for the reason already assigned, that from 

 its levity it rises to the roof of the mine, and the mixture of it 

 with atmospheric air, which is explosive, is always accumulated 

 there. Nor can this increase so as to extend to the floor of the 

 mine, and the miner remain present, as, previous to this, the 

 effect of this mixed air, received by respiration, would be felt, 

 and give warning of the danger. (Note C.) 



The flexible tubes of the moveable lamps may be easily pre- 

 pared, and preserved air-tight and there being so ready a sup- 

 ply of air from below, if there were any minute fissure in the 

 sides of the tube, no air would enter by it, or the quantity 

 would be so small, and so much diluted by intermixture, that 

 there could be no risk. In the fixed lamps, having an iron or 

 copper tube conveying the air, there could be no risk of this 

 kind, and if it were necessary, similar metallic tubes, with 

 moveable circular joints, could be adapted to the moveable; 

 lamps. 



There 



