3C6 



MINE. 



Mines of principles of which, the circulation of air and ventila- 

 Coal. tion depend at the opening of a colliery. 



The double headways course is represented in Plate 

 CCCXCIII. Fig. 11. where a is the one heading, or 

 mine, and b the other. The heading a is immediate- 

 ly connected with the upcast side of the pit c, and the 

 heading b is connected with the downcast side of the 

 pit d. The pit is rendered completely air-tight by the 

 division made of deals from top to bottom, named a 

 brattice wall, so that no air can pass through the brat- 

 tice from d to c, and the communication betwixt the two 

 currents of air is completely cut off by a stopping betwixt 

 the pit-bottom and the end of the first pillar; the pillar 

 or walls of coal, marked e, are named stenting walls ; 

 and the openings betwixt them are named walls, or 

 thirlings, the arrows show the direction of the air. 

 The headings a and b, are generally made about 9 feet 

 in width, the stenting walls 6 or 8 yards in thick- 

 ness, and holed or thirled at such a distance as is 

 found most suitable for the state in which the air is. 

 The width of the thirlings is 5 feet. When the head- 

 ings are set off from the pit- bottom, an opening is left 

 in the brattice at the end of the pillar next the pit, 

 through which the circulation betwixt the upcast and 

 downcast pits is carried on ; but as soon as the work- 

 men cut through the first thirling, No. 1, the opening 

 in the brattice at the pit-bottom is shut, by which 

 means the air is instantly drawn by the power of the 

 upcast shaft through that thirling, as represented by 

 the dotted arrow : this evidently brings a direct stream 

 of fresh air close to the forehead where the work- 

 men are. They then proceed with the two headings 

 n and b ; and as soon as they cut through the thirling 

 No. 2, a wall of brick and lime, four and a half inches 

 thick, is built across the thirling No. I, which building 

 is named a stopping ; this being air-tight, forces the 

 whole circulation through the thirling No. 2. In this 

 manner the air is carried forward, and circulated al- 

 ways by the last made thirling nearest the forehead, 

 care being taken the instant a new thirling is made, 

 that the last thirling through which the air was circu- 

 lating be secured with an air-tight stopping. In the 

 figure, the stoppings are placed in the thirlings No. 1, 

 2, 3, 4, 1), 6, and consequently the whole circulation 

 passes through the thirling No. 7, which is the nearest 

 to the foreheads of the headings a, b. From an in- 

 spection of this figure it is evident, that by this very 

 simple plan, a circulation of air may be carried to any 

 distance, and in any direction however various ; for in- 

 stance, if, while the double headways course a b is go- 

 going forward, other double headways courses are re- 

 quired to be carried on at the same time on both sides 

 of the first headway, the same general principles have 

 only to be attended to as shewn in Fig. 12, where 

 a is the upcast, and b the downcast pit. The air pro- 

 ceeds along the heading c, but is prevented from pro- 

 ceeding farther in that direction than the pillar (/, 

 where it is obstructed by the double doors at e, it there- 

 fore proceeds in the direction of the arrows to the fore- 

 heads at/, and passing through the last thirling made 

 there, returns to the opposite side of the double doors, 

 then ascends the heading g to the foreheads at h, passes 

 through the last made thirling there, and descends the 

 heading i, until it is interrupted by the double doors 

 at k, the air then passes along the heading / to the fore- 

 heads at m, returns by the last made thirling there, 

 along the heading n, and lastly descends the heading 

 o, and ascends the upcast pit a, mixed with all the 

 impurities which it met with during its circulation : 

 this figure or diagram is an epitome of the mode by 



Fig. 12. 



which collieries of the greatest extent are wrought. Mines of 

 The air courses in some are from 30 to 40 miles in Coal- 

 length, so that when the circulation of air is conducted ^"""YJ"""*' 

 by means of a pit divided by a brattice wall only a few . 

 inches thick, the air which is descending the downcast 

 on one side of the brattice, at six o'clock in the morn- 

 ing has to circulate through a course of perhaps 35 

 miles, and at six o'clock at night is only ascending by 

 the other side of the brattice, a division only about 

 seven inches in thickness. From this description of 

 the system of ventilation of coal mines it is evident 

 that the furnaces which are the immediate cause of the 

 circulation, require to be most particularly attended to, 

 and kept in constant regular action night and day, and 

 from year to year, during the existence of the colliery ; 

 any inattention to this duty, stagnates the circulation, 

 and places in extreme hazard the lives of the workmen 

 and the welfare of the colliery. Upon considering the 

 principles explained in these figures, it is evident, that if 

 any number of boards are set off from any side of these 

 mines, either in a level, dip, or rise direction, the cir- 

 culation may be extended to each forehead, upon the 

 principle of an ingoing current to each, and a returning 

 current from the same. 



It requires particularly to be noticed, that although p tATE 

 the circulation of fresh air is thus carried forward to cccxcm. 

 the last made thirling next the foreheads f, h, and m, Fig- 12. 

 Fig. 12. and circulates through the thirling which is Brattices, 

 nearest to the face of every board and room, the dis- 

 charge of inflammable air is frequently so great from 

 the solid coal, that the miners dare not proceed on- 

 wards above a few feet from the current of fresh air, 

 without the danger of being burnt from the gas ignit- 

 ing at their candles. To secure against this accident, 

 temporary shifting brattices are used. They are made 

 of deal about three quarters of an inch thick, from three 

 to four feet broad, and about ten feet long, with cross 

 bars for binding the deals together, and a few finger 

 loops cut through them for the more expeditiously 

 lifting and placing them in exact position. Every col- 

 liery where inflammable air abounds, has a number of 

 those brattices ready for service, and a great store of 

 brattice deals for emergencies, when an explosion un- 

 fortunately takes place. 



The manner of applying the temporary brattices is 

 represented in fig. 1 3, where the air circulates freely Fig- 13. 

 through the thirling a before the brattices are placed. 

 b and c are two headings, boards, or rooms, which are 

 so full of inflammable air as to be unworkable. Props 

 are placed near the upper end of the pillar e, betwixt 

 the roof and pavement, and about two feet clear of the 

 sides of the next pillar, so that the miner can pass along 

 betwixt the pillar side and the brattice. The brat- 

 tices are then fixed with nails to the props, and while 

 the lower edge of the one brattice rests on the pave- 

 ment, the upper edge of the upper brattice is in con- 

 tact with the roof, by which means any variation of 

 the height in the bed of coal is compensated by the 

 overlap of the brattices ; and as the boards advance^ 

 shifting brattices are laid close to and along side of the 

 first set. The miner sets additional props in the same 

 parallel line with the former, and slides the brattices 

 forward, in order that the air may circulate close to the 

 forehead where he is at work, the distance betwixt the 

 brattice and the forehead being rtgulated by the issue 

 of inflammable gas and the velocity of the circulation 

 of the air d d are the pro;:s, and/ the brattices. By 

 this arrangement the air is prevented from passing di- 

 rectly through the thirling , und is forced along the 

 right-hand side of the brattice, and sweeping the wall- 



