MINE. 



335 



coal-field. 



Hydraulic 

 fins 



Mints of sJ, The steam-engine invented by the justly cele- 



*-''- brated \Vatt of Glasgow. 

 ,'"""" """" ' 4th, The high-pressure steam-engine, invented by 



Winning a _, ... 3 



^ZiLM Travethic. 



As the principles of hydraulic and steam-engines, 

 with their general application, are treated of under the 

 articles HYDHMJUCS and STEAM-NOINE, these heads 

 are referred to for minute information ; and therefore 

 we shall only give a very short account of the engines 

 used in the draining of coal mines, making such prac- 

 tical remarks as have arisen from seeing them applied 

 to work. 



The ; .y draulic engine now in use, seem* to have been 

 introduced into the mining operations of England 

 about the year 1680, and into Scotland about the year 

 1712; it was an improvement upon the chain und 

 bucket engine, moved by a water-wheel. Several of 

 the present hydraulic engine* have wheels 30 feet dia- 

 meter, and four feet wide in the water-buckets ; the 

 cranks are generally from two feet and a half to three 

 feet and a half in length, and are fixed upon en-It end 

 of the axle or journal ; there are two beams of wood 

 placed upon a pillar-head or frame of wood ; each beam 

 is about forty feet in length, three feet thick and two 

 feet broad at the centre, tapering towards the end, and 

 firmly bound together with iron glands, and, to pretmt 

 them bending, they have each a kiiii'- |x-t and martin- 

 gale stays ; one of the beams is attached to the crank 

 on one side of the axle by a connecting rod, and the 

 other beam is connected in the name manner to the 

 crank on the other side of the axle, to the other ends 

 of the beams which project over the pit mouth the 

 pear* or pump-rods are attached, which work in the 

 pump*. If the pit is from 20 to 30 fathoms in depth, 

 then two piles or *et* of pumps reacn lrm the bottom 

 to the mouth of the pit, where they l>oth deliver their 

 water ; if the pit is from SO to 60 fathom* in depth, 

 then the depth i* divided. One set of pumpi reaches 

 from the bottom to half-way up the pit, where the water 

 is delivered into a cistern, from which cistern the up- 

 per set or pile of pumps reache* to the top of the pit, 

 where they deliver the water. This machine is of very 

 simple construction ; the working parts are few, and 

 requires no attendance it place* a coal- field drained by 

 it nearly upon a* moderate a footing in point of ex- 

 pense as a coal-field which is leifl-fret, and in some in- 

 stance* even upon a superior tooting. Many attempt* 

 have been made to improve this engine, and to render 

 it* powers more efficient, but without success. 



Newcotnen'* atmospheric steam-engine being of very 

 en'f Meant- simple conitruction, is still generally used a* a pump- 

 ing engine in cullierii-*, hen the Jtind of coal used in 

 working them is of little or no value, ami when the 

 i does not exceed 120 yards; for a greater depth, 

 and here pump* arc u*ed above ten inches diameter, 

 the improved engine of Watt is preferred. 



The steam-engine invented by Watt, known by the 

 name of Watt and Boulton's engine, applied in draining 

 collieries, i of two kind*, named single and double 

 power engine*. 



In the -ingle power engine, the cylinder i* close at 

 the top, and ha* the *team operating against the pis- 

 ton, as it descends, by means of the vacuum formed 

 below it. This engine, like Newcomen's, only draw* 

 water by the descending stroke of the piston; but 

 with much greater power, that is, a much mailer cy. 

 linder is required to produce the ssssje effect. 



In the double-power pumping engine of Watt and 

 Boulton, the piston act* with equal force, whether as. 



N 



wu' 



(IOC. 



cending or descending, so that an arrangement altoge- Minn of 

 ther different is required for working the pumps, be t '* 1 ' 

 cause one-half of the pumps in the pit is worked by ,,~ '.""" 

 the descending, and the other half by tbe ascending of coa i!.fi'Jid. a 

 the piston in the steam cylinder. 



Both the single and double engine of Watt have 

 been applied in a different manner from that before 

 stated ; it had occurred to colliery engineers, that it 

 would be a great improvement in the pumping steam* 

 engine, to throw aside the great and massive lever 

 beam, which in some instances exceeded ten tons in 

 ;. This plan was accomplished by placing the 

 cylinder in a perpendicular direction, directly over the 

 pumps above the pit mouth ; but this plan has not suc- 

 ceeded. It appears th.it u. tiding has been gained by 

 laying aside tile great lever beam, weighty as it is, 

 because, when well-constructed, very little power is re- 

 quired to move it 



Trevethick'i engine is of unlimited power, with re- Treve. 

 gard to the pressure upon each square inch of the pis- thick's 

 ton As it operates by means of steam raised to a great "'am-en- 

 elastic power, it' is employed either as a single or dou- gmc ' 

 ble engine, in the same mariner as the engines of Watt. 

 Tfuy were first applied to collieries in a very simple 

 form, by allowing the steam, which had acted by its 

 pressure on one side of the piston, to t scape into the 

 air, while the elastic (team acted on the opposite side 

 of the piiton, and so alternately. Mr. Woolf ha* ap- Woolfs 

 plied the highly elastic steam principle of Trevethick to ittun-ca. 

 the principle* of Watt'* engine, and these engine* of S'" c - 

 combined principles are now much used in draining the 

 ery deep and heavily-watered mines in Cornwall. 

 Some of these engines work with a pressure of more 

 than four atmospheres on the square inch of the piston, 

 that i*, more than 60 pounds upon the square inch ; 

 I nt they are not in general use, a* a considerable de- 

 gree of danger attend* them. 



Witli respect to the general range of the power of 

 the different kind of engines before described, milling 

 engine, r* are in the practice of calculating their powers 

 according to the weight of the column of water raised 

 fr'im the bottom to the top of the pit, independently 

 of friction, and the tit inert ice which has to be over- 

 come at each incoming and returning stroke, at which 

 points the whole power and movement of the pumping 

 engine mu be brought to rest, and the direction of 

 the power altered. 



The winnings or fitting* of collieries are of various Drpih of 

 depth*, from a few to two hundred fathoms, which "innings. 

 i* the deepest winning in Great Britain, that is, the 

 deepest at which coal* are wrought ; hut the deep- 

 est coal-pit i* only one hundred and fifty fathom*. The 

 depth of any winning or fitting is made to correspond 

 with the capital to be employed, and the vend or sale 

 of coal < which may be calculated upon, according to the 

 state of tne demand for coal ; it being very evident, that 

 a very limited vend will not, t th ..rdin ry rare at 

 which coal* are sold, admit of a great capital being 

 invested in m-iking a winning, either by a day level or 

 bv i .irhmcry. 



The depth of the winning having been determined 

 upon, the manner in which a winning :- made by a day 

 lev. i has been described We have now to utate the 

 manner in which a winning i* made by machinery. 



The depth at which the coul rs to be won regulates 

 the power of the engine to be applied, having in view 

 the probable quantity of water which may be f< : 

 which lait regulates the width of the working barrel of 

 tne pumps, in a district of country where coal* are 

 6 



