MINE. 



377 



Mine* of 



In collieries where water is thus kept back with 

 so heavy a pressure, the greatest caution is required 

 in conducting the adjoining workings, in not ap- 

 proaching too near, the danger being so imminently 

 great 



Working of The working of mines of limestone and ironstone is 

 limestone, conducted on the some principles as those of coal. The 

 greater psrt of the limestones of Great Britain are 

 wrought open cast, similar to a freestone quarry: When 

 they we wrought under cover, it is always with post 

 and stall ; and, if the roof is good, the pillars are very 

 mall, ami the mines very wide. The general system of 

 working is the same as that of coal on the simplest form, 

 little attention being required for ventilation. 

 Working of Ironstone is sometimes wrought open-cast ; and in 

 iremtooc. hill districts where it abounds, as in Wales, the plan of 

 damming and husshing is employed, that is, collections 

 of water are made above the open-casts, and the water 

 from above is allowed to pass through them, which 

 carries down both the ironstone and the argillaceous 

 clay in which it is embedded ; when the water ceases to 

 run, the ironttone is gathered at the bottom of the 

 slope. When ironstone is found in the strata immediate- 

 ly above a coal, the practice is to work the coal first, 

 if in the post and stall ytem ; afterwards to take down 

 the roofs of the rooms and thirling*, and pick out the 

 ironstone. In this way none of the ironstone above the 

 pillars of coal can be got ; but if the common roof- 

 stone comes down in great quantity, the wastes can be 

 so built up as to allow both the pillars of coal and the 

 ironstone above them to be taken away. Ironstones in 

 the roof of coals sometimes render the coal easily 

 wronght in the Shropshire style, both the coal and iron- 

 stone being wrought at once, while the roof-atones fill 

 up the waste, and serve as gobbing, so that none of the 

 coal is required for that purpose. Much ironstone is 

 wrought in the solids, that it, simply as* an ironstone 

 mine, and as the ironstone is in bands and balls of a 

 few inches thick, much of the argillaceous schistus in 

 which it is embedded has to be wrought, in order 

 to give the men room. In this case the Shropshire 

 is universally adopted ; but as the ironstone taken out, 

 bean so small a proportion to the waste which is formed, 

 a great part of the waste stuff has to be brought out of 

 the mine to the surface, there not being stowage l'r it 

 below ; this stuff coven so much ground, that it forms 

 a great objection to the working of ironstone under 

 valuable land. When it happens that a coal is working 

 in the post and stall system, a few fathoms cither above 

 or below the ironstone mine, a cross-cut mine is some- 

 times run from the ironstone workings to those of the 

 coal: through this cross-cut the waste stuff is carried, 

 and stowed up betwixt the coal pillars, by which means 

 the greater part of the pillars can easily be wrought out, 

 which is a great advantage. 



<-.,-... The most extensive collicriei in Great Britain are 

 wrought for sea sale, and are frequently situated at the 

 distance of several miles from the place of shipping, 

 .ch the coals are conducted in waggons upon cast- 

 iron railways. Waggons of various dimensions have 

 been adopted, containing from 10 cwt. to :i tons. Whrn 

 the waggons contain a great weight, the rails require 

 to be very strong, and arc of course expensive. From 

 li to 30 c liaps the most suitable for colliery 



rail-nays . ;, the declination from the 



colliery t place is moderate, one horse 



can take down 8 waggons at a time, each waggon con- 

 taining a ton weight of coals, and return with therrap- 



VOL. XIV. PART II. 



It to 

 iket. 



ty ones. Where great declivities occur, inclined plane Mines of 

 machines are used, by which the full waggons, in de- l 

 scending, pull up the empty ones; if steep ascents occur '"""'Y"*"*' 

 betwixt the colliery and the shipping place, the waggons 

 are taken up by means of a steam-engine placed at the 

 top of the bank. This is attended with considerable extra 

 expence, and it is only at collieries where a great quan- 

 tity of coal is to be vended that this expence can be 

 repaid. Upon some rail- ways, high pressure travelling Travelling 

 engines have been adopted for taking down the coals, enginet. 

 and with very great effect, particularly by Mr. James 

 Stevenson, engineer at Killingworth colliery, New. 

 castle, and by Mr. Blenkensop at Leeds. The former 

 has made great improvements, both in the construction 

 of the engines and rail-ways. By Mr. Blenkensop's 

 plan, teeth are cast on the side of the rail, by which 

 means, with a toothed wheel, the engine can draw the 

 waggons up a declivity of considerable steepness. One 

 of these engines can draw from 30 to 50 tons at a time. 

 For the particular construction of rail- ways -and tra- 

 velling engines, see the article RAIL-WAY. 



The dividing of great coal into separate kind*, term- Divuioa of 

 ed great coal, chews, and small coal, is a very bad coali after 

 system : the best mode for the mine master and con- they are 

 sumer is to have only two kinds, viz. household coal wr oght. 

 and culm ; the household coals being composed of large 

 coals, and of a sue downwards to about an inch, sepa- 

 rated from the culm by a harp, or by a riddle, which is 

 preferable. This correct practice is to be seen in all the 

 collieries of the Glasgow district in Scotland ; by it the 

 greatest economy is produced, not only in respect of the 

 coal, in a given*rca, ; : the greate>t quanti- 



marketable coal* ; but the open burning coals, when 

 from culm, are the best fitted for every general purpose ; 

 whereas the culm cao be afforded at a very cheap 

 for steam-engines lime- burning, salt, and brick- mak- 

 ing, it being well known that when culm is mixed with 

 the round coal, it retards the burning in an uncommon 

 degree. The great coal system, where three -;/.-s are 

 made, if attended with much losa of coal, and greatly 

 enhances the price of what is termed great coals, these 

 being generally 30 per c- r than the chews, 



while, at the >amc time, they must be broken down to 

 the size of chews by the consumer, before they can be 

 put into the fire. This shews how very detrimental this 

 system is. 



At Newcartle, where the coals arc of a rich caking Ruinous 

 quality, and where every particle of them is of equal yitcm of 

 value, a very bad system has been introduced, of sepa- dividing 

 rating the smaller part of the coal from the other, lhe **'"" 



ms of skrcens or harp. The small coal forma ' fotl '' 

 excellent smithy coal, very lit for glass-making, and in- 

 deed for almost any purpose. Tnis separation of the 

 small coal arose from the violent competition of the 

 coal owners in the London market, in order to gi\ 

 coals a better appearance. The system was very easily 

 introduced, but it has now extended to such a degree, 

 that it seems to carry ruin with it as to the economy 

 of the coal-field.* in tin- north of England, for the fine 

 coals thus separated < . the consequence is, 



that at every colliery they accumulate to such a degree, 

 that they ;,re either allowed to take fire by spontaneous 

 i, or are actually set on lire in order t. clear the 

 ground of them. It i> the burning ol'thk kind of cool 

 which a.stoni.shes all strangers whoappn istle 



at night, from the innumerable bright blazes seen in 

 lirection. The waste and destruction of coal by 

 this system has extended now to such on uncommon 

 3 



