M I N E. 



365 



CoO. 



Venlilj- 



lion. 



Air pum{K 



Jam ten. 



PLITI 

 cctcu 



r, s . ft 



air issues from the cutter* of the rock ami beds of coal, 

 which has to be attended to and carried off for the - 

 of the workmen ; and no sooner is the coal gained at the 

 pit-bottom, which is the great object of all his labour;, 

 than an immediate and most careful attention is rcquir- 

 secure a circulation of air, there being instances 

 where the workmen dare not advance even six feet into 

 the whole wall, or solid coal, without having the circu- 

 lation of fresh air brought within three feet of the fore- 

 bead where he works. When th lered, and 

 when it is known that, in practice, the air is carried for 

 many mile* in regular labyrinths through the wastes, 

 and along the distant and widely-extended wall-faces, 

 where every room requires its ventilation to lie attended 

 to ; and as upon the correct ventilation, the lives of the 

 workmen, and prosperity of the mining concern depend, 

 some faint idea may be formed of the important and 

 arduou^ duty i>f the mining engineers in these districts, 

 and of the evere application of mind, and laborious 

 toil they incessantly undergo, and patiently endure. 



The chief and general plan practised by these engin- 

 eers, in those very deep and extensive collieries, to pro- 

 duce circulation, is by means of ratifying the air at the 

 upcast shaft, by a very large furnace placed either at the 

 top or bottom of that shaft. The latter is the best, and 

 generally preferred. 



Another method is by exhuustion, effected by an im- 

 mense air pump, wrought by machinery ; and, in ex- 

 treme cases, the cascade, or water-fall, is resorted to. 



W hen the furnace i* placed at the top of a pit, it is 

 constructed according to what is represented in Fig. 3. 

 Plate CC'CXC I. When it U placed upon a single pit, 

 or upon one of the division* of a pit, the pit 

 is thus to be the upcast is made air-tight t t><; 

 placing strong buntons. or beams across it, at any con- 

 venient distance from the mouth : upon which bunions 

 close scaffolding of plank i* laid, and. for farther se. 

 curing its being air tight, it is moated over with well, 

 wrought plastic clay. At a little distance below the 

 scaffold, a passage is previously cut. either in a loping 

 MIII, to connect the current of air with the furnace, 

 or it is run horizontally, and communicates with the 

 furnace by a perpendicular opening. If there be any 

 obstacle to the placing of the scaffold down in tl 

 the pit can be made air-tight at top, and an air tube of 

 brick carried along the surface to the furnace. These 

 furnaces are made of a size corresponding to the r 

 of ventilation to be carried on, and the chimneys are 

 conn cr round or square, from SO to 100 feet 



in height having an inside diameter of from * to p feet 

 at bottom, and tapering to 2 feet 6 inches or to 5 feet dia- 

 n t the top, proportioned to the haight and diameter 

 at bottom. These chnimey, having so great a taper, rr- 

 quirc on I;. -chi-s thick, or one brick in 1, 



excepting a lining at the bottom of fire brick, where the 

 beat of the furnace acts with force. 



Although these furnaces placed at the surface are still 

 used, yet they are in a great degree superseded by the 

 more effectual plan of placing a furnace at the bottOB 

 of the pit, which is much more effectual than the for- 

 mer, for this reason, that the shaft through which the 

 air ascend* to the furnace at the top of the pit, is always 

 at the ordinary temperature ; from w hich can 

 rt*" 1 the not attended to. and allowed to 



grow languid, the circulation of air through the mines 

 grows languid in a corresponding degree, and conse- 

 quently dangerous, whereas, when the furnace is plac- 

 the bottom ..f the pit, the shaft is heated through 

 its whole length ; the consequence of which is, that al- 

 though the furnace should be neglected, and grow lan- 



guid, and although the fire in it be quite extinguished 

 tor a considerable time, the circulation will continue to 

 be good, as the ahr in the upcast pit is rarified by the 

 heat remaining in the shall walls. When furnaces 

 were first placed at the bottom of the pits, or at a little 

 ice under the roof of the coal, the smoke which 

 proceeded from them, and the air highly heated, ren- 

 dered it impossible for the onsetters to work there. 

 The consequence of which was, the pit in this case was 

 of no use for drawing coals. Of late, this fault has 

 been obviated, by adopting an improved plan, as re- 

 presented, Fig. 9. Plate CCCXCIII. where a is the 

 lower part of the upca-st shaft ; b the furnace built of 

 brick, arched at top, and the sides imulated or built 

 clear of the solid coal in which it is placed. Betwixt 

 the sides of the furnace wall and the coal, a small cur- 

 rent of air constantly passes to the shaft, to prevent the 

 coal taking fire. The furnace is wide, and open in 

 front, that the air may have a free passage over the 

 burning coals ; and the coals burn upon furnace bars, 

 having an ash pit below them similar to the construc- 

 tion of furnace* used for engine boilers. The furnace 

 is placed at any convenient distance from the pit bot- 

 tom, such as forty yan!s. From the end of the furnace 

 a mine is cut in a rising direction at c, and commu- 

 nicates with the shaft at H, at the distance of from 6 

 to 10 fathoms from the bottom of the pit. By this ex- 

 cellent arrangement, the furnace and furnace- keeper 

 are completely disjoined from the pit. The pit bot- 

 tom is not only free from all incumbrance.*, but is cool 

 and temperate ; and the shaft is at the same time as ser- 

 viceable as any other for the drawing of coals. As the 

 heated and vitiated air, with the smoke, are not only 

 very unpleasant and troublesome to the banksmen, 

 who work close to the pit mouth ; but as much machi- 

 nery is so frequently employed at a Newcastle pit hav- 

 ing three or four divisions, with frequently one or two 

 Urge water drawing engines, with two coal-drawing 

 engine*, these tloely grouped together around a nar- 

 row pit mouth, not only greatly obstruct the ascend- 

 ing and descending currents of air, but the force of 

 high winds has often had the effect of beating down 

 the ascending current of air, and throwing the whole 

 circulation below ground into a languid, dead, and dan- 

 gerous state. To obviate this, the following plans 

 have been successfully adopted, a shewn in Fig. 10, 

 which represents the top of a Newcastle coal pit. a 

 the u point shaft, with the furnace at bottom ; b the 

 downcast shaft, by which the fresh atmospheric air de- 

 scend* ; d the brattice carried above the pit-mouth. 

 At a little distance below the settle boards, a mine 

 f ii carried to communicate with the surface from the 

 downcast shaft, over which a brick tube or chimney is 

 built from 60 to 80 feet hich, from (>' to X feet diameter 

 at bottom, and from 3 to 5 feet diameter at top. I 'pon 

 the top of ttiM chimney a funnel, made ot deJ, is pla- 

 ced in a horizontal direction, which turns easily round, 

 being hung upon a pivot. The vaneyj made also of 

 deal, keeps the mouth always opposite to the <lir< 

 of the wind. An arrangement, exactly similar in every 

 respect, is made at the upcaxt shaft a. with this diffe- 

 rence, that the funnel is constructed to turn its mouth 

 in the direction of the wind. From an inspection of 

 the Figure, the effect of this arrangement will be seen, 

 so that a high wind rather aids than injures the ven- 

 tilation. 



The principle of ventilation being thus obtained, the 

 next plan in opening up a colliery, and in driving all 

 advance mines whatever, is the double mine, or douilt 

 htadtrayt cnrte, upon the simple yet very ingenious 



Mint* of 

 Coal. 



Ventili- 

 tion. 



Pi ATE 



ccriciii. 

 Pig. 9. 



Kig. 10. 

 Air tube*. 



Double 



head-wars 



count. 



