344 



MINE. 



Mines of improvements of this plan, executed by Mr. Buddie, 

 where there was a pressure of several hundred feet, the 

 se j? ments were six feet long, and two feet deep, an inch 

 coal-field, thick, counterforted with raised work on the back ; the 

 lip of the flange was strong, and supported by brackets. 

 These iron segments of a cylinder are set true to the ra- 

 dius of the pit ; and every horizontal and perpendicular 

 joint has sheeting deal in it. A wedginp crib is fixed 

 at the bottom, and the segments are carried regularly 

 up, having the joints like ashler work. This kind of 

 tubbing can be carried to any height, '\intil the water 

 finds an outlet at the surface, or strata containing wa- 

 ter can be tubbed off, as by the other kinds of tubbing 

 before described. A pit completed in this manner pre- 

 sents a smooth shaft wall of iron, the flanges being to- 

 wards the outside of the cylinders. In this work no 

 screwed bolts are used for joining the segments toge- 

 ther. In a pit in the Newcastle district, 70 fathoms 

 have been executed in this manner, under Mr. Buddie's 

 directions. 



Wedging of When a thin bed or parting betwixt two of the stra- 

 cutters. ta which are impervious to water, produces much wa- 

 ter, or when the cutters or fissures in the strata do so, 

 this water can be completely prevented from flowing 

 into the pit by wedging, for which there is a parti- 

 cular method. In place of attempting directly to wedge 

 the fissures, as was the former unsuccessful practice, 

 the fissure is cut open with chissels, and made about 

 two inches wide and seven inches deep, as represented 

 PLATE Fig. 16. Plate CCCXC.; the lips are rounded off about 

 cccxc. an inch and half; pieces of clean deal are then driven 

 Fig. 1C. in, the face of which comes no farther than, the con- 

 tour of the lips; the whole is then firmly wedged, till 

 all the water is stopped back. By placing the wedging 

 back from the face, the rock is prevented from burst- 

 ing during the operation, which always happened in 

 the former process. 



Ventilation In sinking engine pits, besides contending with the 

 when sink- water, ventilation has to be attended to, on account of 

 ing pits. the pernicious airs or gases found in the strata, and 

 - which at times come off in great quantities. These 

 gases are carbonic acid or fixed air, and carburetted 

 hydrogen or inflammable air. The first of these gases 

 being heavier than the atmospheric air, sinks to the 

 bottom of the pit, and filling it up like water, displaces 

 the common air, until it flows over the mouth of the 

 pit. This air instantly extinguishes flame, and de- 

 stroys animal life. The other gas, being lighter than 

 air, instantly ascends the pit, mixed with common air. 

 If this gas is much' diluted with the common air, the 

 workmen suffer no inconveniency from it ; but if pure 

 and unmixed, it destroys animal life, or if mixed with 

 certain proportions of common air, it suddenly explodes 

 and burns the workmen. These gases will be parti- 

 cularly noticed when the ventilation of mines is treat- 

 ed of. 



In ordinary cases, while pits are sinking, the brat- 

 tice walls produce a circulation, by the air descending 

 upon one side and ascending by the other. If this 

 does not take place, the circulation must be produced 

 by fire rarifying the air. 



The most approved method is to cover the engine- 

 pit area of the shaft with deals, having apertures for 

 the pump spears and tackling to pass through, with 

 hatch-doors for the men going up and down; near the 

 top of the pit, and immediately under this scaffolding 

 a. tube of brick, at least three feet square, is carried in 

 a horizontal direction, and connected with a furnace 

 having a high chimney with double doors, where the 

 2 



person enters to throw coals on the fire, as represented 

 Fig. 3. Plate CCCXCI. where a a are the double 

 doors, b the mouth of the horizontal tube from the pit, 

 c the furnace, d the ash pit, e the furnace building 8 

 feet high, arched with brick, / the chimney, which 

 is from 50 to 100 feet high, according to the draught 

 required, from 8 to 10 feet square at bottom, and ta- 

 pering upwards to three or four feet, inside measure. 

 The chimney- wall needs not exceed nine inches in thick- 

 ness, if built of brick, after passing the extreme heat 

 of the furnace, which is about 12 feet high, where there 

 is a lining of fire brick; furnaces of smaller dimensions 

 may be sufficient, in cases where they are only to bs 

 used while the pit is sinking ; but those of large di- 

 mensions are suitable, not only for ventilating the pit, 

 but the workings of the colliery afterwards. In some 

 cases the horizontal tube is connected with the chim- 

 ney of the engine furnace, with good effect, for the ope- 

 ration of sinking. 



Another process is, that in place of covering the en- 

 gine-pit area where the pumps are, as before described, 

 to connect with the horizontal tube, deal boxes, having 

 an internal area of from two to four feet. These are 

 carried down the pit to within a few yards of the bot- 

 tom, and produce a circulation of air, by being con- 

 nected with a furnace at top; for as the air ascends 

 through these pipes by entering at the lower part, the 

 fresh air descends to supply its place. A temporary 

 expedient is used in pits of a very moderate depth, by 

 means of air boxes carried from the bottom of the pit 

 to 12 feet above the surface, upon the top of which a 

 hopper-shaped funnel is placed in a horizontal direc- 

 tion, which being turned with its aperture to the wind, 

 sends a supply of fresh air down the pit. This plan 

 is of no use in deep pits, or where the gases are very 

 abundant. If a great quantity of gas issues from one 

 place in the pit, it is found expedient sometimes to con- 

 fine it in a tube, and conduct it to the top of the pit, 

 where it dissipates into the air. 



In those pits where it is proposed to draw a great 

 quantity of coals, and with very considerable velocity, 

 it is the practice to widen them at the place where the 

 ascending and descending baskets of coal pass one an- 

 other, which is termed the meetings. If there are two 

 or three beds of coal in the pit, there will of course be 

 different places for the meetings, as they are placed at 

 half-way betwixt the mouth of the pit and the coal 

 which is working. The common practice is to make 

 the pit 32 inches wider in the middle, that is, 16 inches 

 wider on each side. It is evident that these cannot be 

 made when there is tubbing in the way ; and if there 

 are many beds of coal to work in the same pit, it is 

 better to make the pit of sufficient width from top to 

 bottom. 



The stones and rubbish produced in sinking are 

 drawn up with horse-gins, when the pit is not deep ; 

 but in all pits of any considerable depth, the rotatory 

 steam-engine is used, and the workmen have now 

 more confidence (as to their personal safety,) in these 

 machines, than in the horse-gins. 



The great collieries of Newcastle are frequently 

 wrought by one shaft, divided in the manner before 

 mentioned, which serves as an engine-pit and coal-pits, 

 and by these the whole ventilation is carried on to an 

 extent altogether astonishing. This system is followed, 

 on account of the immense expense which requires to 

 be laid out upon a pit of this kind, an expense amount- 

 ing in some cases from L.40,000 to L.80,000, includ- 

 ing the machinery. In general, however, the collie- 



Winning * 



coal-field. 

 FIAT. 

 cccxc r. 

 Fig. 3. 



Widening 

 of pits at 

 the meet- 

 ings. 



Newcastle 



system. 



