1816.} On the Ventilation of Coal-Mines. 293 
the tube must open into the upcast shaft at D.* We have already 
seen, that, whatever kind of air may be contained in a similar tube, 
and in a similar position, it may be made to proceed upwards, by 
the application of heat. In this case, however, it will act of itself; 
but will, of course, be assisted by heat, which may be applied by 
surrounding a foot or two of it with boiling water. This tube may 
be made of any materials which may be supposed to answer best, as 
cast-iron, sheet-iron, wood, &c.; and may be made of any form, 
flat, square, or round. If made of thin deal, which will be 
cheapest, that part of it which will be immersed in hot water 
must of course be made of iron. 
The occurrences of falls from the roof, and of blowers, are by 
far the most formidable of the obstacles which can happen to pre- 
vent or to hinder this system of ventilation from producing its full 
effects : and while your readers are estimating the probable efficacy 
of the means proposed to obviate them, it is proper to inform 
them, that there is scarcely any standard of comparison to measure 
it by; that these obstacles occur under the present system of ven- 
tilation in all their pernicious force, without having been obviated, 
' or even successfully limited. 
Many of your readers must, by this time, be desirous of know- 
ing something of the mode of ventilation at present employed, for 
the purpose of comparing it with the system which is here pro- 
posed. And it happens most fortunately, that the Annals of Philo- 
sophy will furnish them with the means of so doing. At page 
355, vol. i., of the Annals of Philosophy, they will find a most 
luminous description, (accompanied bya plate) of the workings of 
the Felling colliery, on the 25th of May, 1812, on which day the 
fire-damp exploded, hurrying, under most awful circumstances, no 
fewer than 92 persons into eternity. The terrific scene cannot 
be better described than in the words of the humane author. 
* When,” says he, “ the air has proceeded lazily for several days 
through a colliery, and an extensive magazine of fire-damp is ig- 
nited in the wastes, then the whole mine is instantly illuminated 
with the most brilliant lightning—the expanded fluid drives before 
it a roaring whirlwind of flaming air, which tears up every thing in 
its progress, scorching some of the miners to a cinder, burying 
others under enormous heaps of ruins shaken from the roof, and, 
thundering to the shafts, wastes its volcanic fury in a discharge of 
thick clouds of coal dust, stones, timber, and, not unfrequently, 
limbs of men and horses.” + 
On reference to this narrative, and to the plate by which it is 
illustrated, the mode of ventilation at present in use will be found 
correctly exhibited: and on comparing it with the proposed system, 
* As it will not again he necessary to refer to the figures, it may be proper to 
say, that they are not constructed on any regular scale of proportion; being 
ity | intended to elucidate the application of the general principles. 
+ Page 9 of the Narrative, and page 359 of the dnnals. ° 
