MINE. 



3G3 



Mine* of economy. Pi-r^nrn who suffer from these deleterious 

 Co*' , me recovered, if carried immediately into good 







A* to the formation of these gases in coal, many theo- 

 ries have been brought fur ward, but none of the con- 

 ns are quite satisfactory. 



It :.* the opinion of many, that the iron pyrites, which 



bounds so much in many coals, is the cause of the 



format:. ai of carburetted hydrogen. The objection to 



. that atmospheric air is not found issuing 



from the coal, and when the coal i opened up by inin- 



ilte pyritt -s is found in its natural state without any 



marks ot decomposition. 



That the hydrogen abounds already formed in the 

 cool, is proved by this fact ; it frequently happens, 

 when searching for coal by boring, that the instant the 

 boring-iron perforated the coal, the gas came off in 

 great quantity, and continued to do so for a long pe- 

 riod. These issues of gas from a bore-hole, have been 

 ignited, and kept burning for month - 



The production of these gases, renders the system of 

 the ventilation of coal mines, a chief point in the sys- 

 tem of mining, particularly where the inflammable air 

 abounds, by which the lives of the workmen and the 

 prosperity of the mining concern may be instantly de- 

 stroyed. 



It would require a long dissertation, and the most mi- 

 nute detail, to give a clear view of the almost infinite 

 variety of cases connected with the accumulation of in- 

 flammable air in the mines of a colliery, and of the 

 plans and methods which have to be employed and va- 

 ried for the ventilation, corresponding to each particu- 

 lar situation of the mines, the workings of which may 

 be either upon a very extended, or very limited scale ; 

 nothing nhort of along tried experience is equal to the 

 task. The safety of the workmen depend* in (great degree 

 upon the skill of the mining engineer who conducts the 

 work. A high responsibility is attached to the charge ; 

 and there cannot be greater presumption than for any 

 man, however intelligent and active regarding mining 

 concerns, where there is no inflammable air, to under- 

 take the management of a colliery infested with it ; un- 

 less he has been regularly trained to the business, and 

 has, in the coune of that practical education, seen 

 " the service" in all its intricate varieties. We shall en- 

 deavour to explain, in a manner as concise as possible, a 

 few of the general plans of ventilation, beginning with 

 the most simple, and going on progressively to the most 



cate. 



The least dangerous gas, and the most simple to ma- 

 nage by ventilation, is the carbonic acid. 



Carbonic I n many instances, the ventilation of such mines, 

 particularly where the depth is not great, is conducted 

 with very little trouble, the practice U-ing to work 

 them with a number of pits sunk in succession. 

 When an engine pit is sunk to the coal in the manner 

 before described, the only difficulty is to convey air to 

 the second pit from the bottom of the engine pit, which 

 is effected in several ways. 



Air pipes. If an air pipe has been carried down the engine pit 

 for ventilation while -inking, additional pipes are con- 

 nected with the upright pipe, and laid along the pave- 

 in, nt, or are attached to one of the corners of the mine 

 next the roof. These pipes are lengthened as the mine 

 proceeds ; by which means the air at the forehead is 

 drawn up the pipes, and its place is supplied l>y atmo- 

 |ihrrir air. which descends the shaft in a con-taut equal 

 current, v j ulatetl by the draught of the furnace 



at the pit mouth. This operation is continued until the 



miners cut through upon the second pit, when the air pipes Mines of 

 are no longer of any use ; for it is a fact well known, ^ al - 

 that the instant such communication is made, as repre- y~"7Y" 

 sented in Plate CCCXC ill. Fig. 6, the air spontaneous- tio e n ' 

 ly descends the engine pit A, and passing through the f, g . g. 

 mine a, ascends in a constant current up the second pit 

 B. The air in descending A is of the temperature of 

 the atmosphere, and in winter will freeze water from 

 the top to the bottom of the pit ; but its temperature 

 is increased in passing through the mine, and ascends 

 the shaft B at a temperature greatly increased. When 

 pits are of unequal depths, as represented in the Figure, 

 the current of air is very uniform, and in one direction. 

 If the second pit was of the same depth, and the bot- 

 tom and mouth of each in the same level plane, the air 

 would net remain stagnant as in .in inverted syphon 

 filled with wcter. but would of its own accord circulate 

 down one pit and up another, not regularly in one di- 

 rection, but would sometimes circulate the one way and 

 sometimes the other, according to the changes of tern* 

 perature at the s'urface, modified by calms and strong 

 winds. There is in coal mines an internal heat, which, Tcmjwra- 

 from the experiment* we have made, varies from the lure of cod 

 common average temperature of air, and springs of mines. 

 water at the surface of the earth, tu a temperature of 

 77* of Fahrenheit. There are caaes, where pits are 

 sunk, and communications made, without a circulation 

 being produced either by pipes or ventilation tubes ; 

 and it at any time the air became dull at the forehead, 

 it was invigorated by pouring a few puncheons of wa- 

 ter from the pit mouth down the pit. If this was Air rig- 

 not successful, there is a simple plan of carrying air glin. 

 from the pit bottom to the forehead of the mine, by 

 cutting a ragglin or trumpeting, as it is termed, in the p 

 side of the mine, as represented in Fig. 7, where A is .*" 

 the mine in the coal, and B the ragglin, which is from p, g _ 7. 

 15 to 18 inches square. The coal serves as three sides 

 of an air pipe. The fourth side next the mine, is co- 

 vered with thin deals made air tight, and nailed to 

 small props of wood fixed betwixt the top and bottom 

 of the lips of the ragglin. This is a mode very gene- 

 rally practised in running mines of communication, and 

 dip-head level mines, where carbonic acid abounds, or 

 when air is liable to become stagnant, and dillteult for 

 the support of the light by which the ninu-r work-. 



When a circulation is not effected by the ragglin or Ventila- 

 air pipes, which proceed from the volume of freih air img ian- 

 at the bottom of the pit, the air is sometimes im- '"" 

 pelled through them, by means of ventilating fan- 

 ners, the tube from which is placed at the pit Bot- 

 tom, and the vanes or leaves of the fanners are impelled 

 with great velocity by means of a wheel and pinion 

 wrought by the hand. In other cases, large bellows, si- BUOWS. 

 milar to those used by smiths, with a very wide noz- 

 zle, are applied in the same manner as the fanners. 

 These methods are only used as a temporary resource, 

 when the mines have not to be carried to any gr t 

 distance. The circulation thus produced by propell- 

 ing, in place of educting the air, is very faint, and the 

 pulses feeble. Trials have been made with the bel- 

 lows, by inverting their common mode i>f action ; that 

 i", by attaching the air pi|K- to their under valve. Hy 

 this plan the air is educted, and blown nut or discharg- 

 ed at the nuzzle. We conceive this plan would tic very 

 suitable for sinking shallow pits or wells, where there 

 wa* no great accumulation of carbonic acid. The appli- 

 catio-i of the ventilating fanners in the s.une manner, we 

 presume, in many case* would In- an improvement, from 

 the great obstacles presented against the propelling of 



