364. 



MINE. 



Mines of 

 Coal. 



Ventila- 

 tion. 



Water fall. 



Air funnel 



Bearing 

 doors. 



PLATE 

 CCCXCIII. 

 Fig. 8. 



air through pipes, although a very strong force is ap- 

 plied. 



Another of the simple methods pursued in ventila- 

 ting mines which are level free, and where this gas 

 abounds, is to allow a small quantity of water at the 

 pit head, to fall freely down a pipe of a foot or eighteen 

 inches diameter. This water carries down an aston- 

 ishing quantity of air with it, and the water and air fall- 

 ing into a cistern at the bottom of the pit, the air se- 

 parates from the water, and is by its accumulation and 

 elasticity propelled along the pipes below ground to the 

 forehead, or is allowed to diffuse itself freely along the 

 minei, and through the workings of the pit. 



Ventilation is also produced in collieries upon a small 

 scale, by placing a horizontal funnel at the top of air 

 pipes elevated a considerable height above t^he pit 

 mouth. The funnel turns round upon a pivot, by means 

 of a tail-piece moved by the wind, so as to present the 

 mouth of the funnel always to receive the wind ; or a 

 circulation is produced by having fires of coal in iron 

 grates either at the bottom of an upcast pit, or suspend- 

 ed by a chain some fathoms down ; and we have seen, 

 on an emergency, when there was a breeze of wind, a 

 ventilation produced by placing an awning of canvas 

 in a perpendicular direction, and in a semicircular form 

 around the lee-side of the pit mouth ; the canvas being 

 suspended on temporary uprights of wood. 



These are the ordinary methods generally practised 

 in collieries of a moderate depth, where carbonic acid 

 abounds, or where there is an absolute want of air. In 

 such cases, the circulation of air through the wastes, and 

 along the wall faces is very easily managed, and with 

 very little expence, the air descending the engine- 

 pit, and ascending one to the rise. 



In all coal-mines the circulation of air is regulated as 

 to its line of direction, by double doors, named main- 

 doors or bearing doors. They act as air-valves, and cut 

 off a current of air, going in one direction, from joining 

 or mixing with a current of air proceeding in another. 

 These doors are placed upon the main roads and pas- 

 sages in the mine, and are of great importance in ven- 

 tilation. Their mode of operation is represented in Fig. 

 8. where A is the downcast, B the upcast pit, sunk to- 

 wards the rise of the coal, and C the dip-head level. If 

 in this case the mines were wrought without any atten- 

 tion being paid to the circulation of the air, it would 

 descend the pit A, and proceed in a direct line up the 

 rise-mine to the pit B, where it would ascend, the con- 

 sequence would be, that all the mines and boards to the 

 dip of the pit A, and lying on each side of the pits, 

 would have no circulation of air, or would be laid dead, 

 *s it is termed. To obviate this, double doors are placed 

 in three of the mines adjoining the pit, viz. at and b, 

 c and d, e and./ ; all of which open inwards to the pit 

 A. By this arrangement, the air being prevented from 

 passing directly from the pit A to the pit B, by the 

 rf*,ors a and b, it would have taken the next and nearest 

 direction by c, d, and e,J '; but the doors in these mines 

 prevent this, it therefore must proceed downwards to 

 the dip-head level, where it will spread or divide, one 

 portion taking a course to the right, the other to the 

 left. Upon arriving at the boards g and h, it would na- 

 turally have ascended by them ; but this is prevented 

 by a building, or stopping, placed at g and h. By 

 means of these stoppings placed in the boards next the 

 dip-head level, the air can be carried to the right or left 

 hand for miles, if necessary, providing there is a train 

 or circle of communication -of air from the pit A to B. 

 Suppose the boards i and k are open, the air will ascend 



them, as shewn by the arrows ; and, after being diflus- Mines of 

 ed through the workings, will again meet in a body at Coal. 

 a, and ascend the mine to the pit B, having combin- 

 ed with it the deleterious air which it found in its pas- 

 sage. Without double doors on each main passage, the 

 regular cii dilation of the air would be constantly inter- 

 rupted and deranged ; for example, suppose the door c 

 removed, and only d remaining in the left-hand mine, 

 all the other doors remaining as they are, it is evident 

 that the instant the door d is opened, the air finding a 

 more direct passage in that direction, would ascend by 

 the nearest course /, to tbe pit B, and lay dead all the 

 other parts of the work, there being no longer any cir- 

 culation. Asthe passages upon which the doors are plac- 

 ed are the chief roads by which the workmen pass and 

 re-pass to their work ; and as the corves are also constant- 

 ly passing from morning to night, a single door, such 

 as d, would be so often shut and opened, that the ven- 

 tilation would be rendered very languid. The double 

 doors completely correct this fault ; for when men, or 

 horses with loaded corves, are proceeding to the pit 

 bottom A, the door d is opened, and as soon as they 

 pass, it is shut, so that they are in quiet or still air, con- 

 tained betwixt the doors d and c, as c prevented the 

 air from changing its course while d was open ; when 

 d is thus shut, the door c is opened, when the men and 

 horses pass on to the pit-bottom at A, the door d pre- 

 venting any change in the circulation ; while the door 

 c is open ; the men and horses, in returning from the pit, 

 observe the same rule, first opening the door next them, 

 then shutting it before they open and pass the other. 

 By understanding this mode of separating and disjoin- 

 ing air courses from each other, the continuance of this 

 separation in a working of any extent, will be easily 

 comprehended. When carbonic acid abounds, or when Stoppings, 

 the carburetted hydrogen is in very small quantity, the 

 air is conducted from the pit to the dip-head level, and, 

 by placing stoppings in the off-break of each room next 

 the level, it is carried to any distance along the dip- 

 head levels ; and the farthest room on each side being 

 left open, the air is allowed to diffuse itself through the 

 wastes, along the wall faces, and to ascend the upcast 

 pit, as represented in Fig. 13. Plate CCCXCI.; but if P" 

 it should happen that the air becomes stagnant along p' cxc ,'i 

 the wall faces, stoppings are put up through the work- 

 ings in such a manner as to direct the main body of fresh 

 air to pass along the wall faces for the workmen, while 

 a partial portion of the air is allowed to pass through 

 the stoppings to prevent any accumulation of bad air in 

 the wastes. In such cases as have been mentioned, the 

 stoppings are made in a very superficial manner, with 

 stones and rubbish, and frequently with rubbish alone, 

 there being no danger from an explosion taking place. 



The mode of ventilation thus described is very simple, 

 and the consequences of any inattention or mistake, are 

 generally not of a very alarming nature, nor fatal to the 

 workmen, or very injurious to the interest of the con- 

 cern. But \^here the inflammable air abounds, as in 

 many of the districts in England, particularly in the 

 counties of Northumberland, Durham, and Cumber- 

 land, a very different field of action is presented to the 

 mining engineer. There a host of difficulties attend him 

 at every step, from the moment he breaks the ground for 

 the fitting, or winning of a colliery, to the day in which 

 the last corve of coals ascends the pit. Water, mud, 

 and quick-sands oppose his progress in passing through 

 the alluvial cover ; and in the rock strata, beds of stone, 

 yielding vast quantities of water, have to be stopped by 

 cribbing or tubbing, and frequently much inflammable 



