$86 
ing to the strength of theroof, or stratum 
over the coal, “and the firmness of the 
foundation on ‘whieh they stand; as well 
as the soundness and strength of the coal 
itself. The manner then of getting the 
coal, is what the colliers cali by stalls, 
that i is, by alternate pillars: and excava- 
tions, which pillars are not: afterwards 
hollowed out, as in the northern’ col- 
lieries. Consequently, a much larger 
proportion of the coal is left ungot in our 
collieries. Tt is generally reckoned, that 
one-third part of the coalis left in pillars, 
and that about another third is inssmall 
coal, part of which is made into coaks, 
and another part is consumed by the fire > 
engines belonging to: the colliery, and 
other works in the neighbourhood, and 
the rest is left in the pit. Accordingly, 
there remains only about one-third of the 
mine to be sold as large, marketable coal. 
This mode of getting “the coal, differs still 
more from the method called long work, 
practised in Shropshire. The gna: is 
supported during working by buttresses, 
of which the outsides are made of wood 
and large coal, and the insides are filled 
with sleek. 
The great height of the wists makes it 
necessary to cut and make it fall, at $€- 
veral different operations. When the 
pits are’ sunk, and communication made 
with the engine-pit, for the water to run 
towards it; and also gateways, or reads 
made for the conveyance of coals to the 
shaft of the pit, the colliers begin to get 
coals by working astall. T his they ‘do 
by cutting out the lower bed, called the 
Humphries; the length of their stall, ten, 
twelve, or fourteen yards ; and when they 
have thus removed the foundativn of the 
coal to a certain breadth, they. then 
Joosen its adhesion to the sides, by cut- 
ting as high as the beds called slipper and 
sawyer, which accordingly make the first 
fall of coals; the stone-coal makes the 
second fall; the .John-coal, or slipps, 
makes the third ; the foot-coal makes the 
fourth; the brassil makes the fifth; the 
benches and tow-coal makes the sixth; 
the lambs make the seventh; the Jays 
make the eighth; the top-slipper the 
ninth; and the roof is seldom cut, but 
only as much of it goes, as drops spon- 
taneously, and can ie sately collected. 
Tt is the facility of separation, by means 
of the partiugs,between the beds of coal, 
‘that principally determines these differ- 
on ee: From this short account of 
the “differences which distinguish . this 
different mode of getting this very thick 
mne, from the ordinary thin miucs, we 
may easily conceive the greater ditiiculty, 
M ineralogy of the South-West of Staffordshire. 
{ Noy. 1; 
expense, danger to workmen, and waste 
of mine, which attends the collieries of 
this county, and which considerably di- 
minish the advantages arising from the 
greater quantity. ‘To the above-nien- 
tioned disadvantages, we may add the 
frequency of fires spontaneously kindling 
in our pits, from the great quantities of 
small coal, or sleek, which are left there;’ 
not only heeause there is not sale for the » 
whole of it, but also because it is by 
ineans of heaps, orsicek, that the colliers 
_ ean reach to cut the upper beds of the 
coal, the fall of which 1s also thus short- 
ened, and the breaking of the coal ito 
small pieces, thereby prevented. But in 
thin mines, this sleek may be raised 
above ground; and when the coal is of a 
caking quality, it is saleable. Having 
shortly mentioned the pecujiarities which 
aitend our collieries, I shall not enter 
upon what is cemmon to all others; as 
the methods of boring and sinking, of - 
giving a free and permanent passage to 
_the water, from different parts of the. 
colliery, to the engiue-pit, where it is dis- 
charged; of producing a circulation of 
the external air, 1n the different passages 
and openings of the mine, for the respi- 
ration of the ecolliers, and for the dis- 
charge of any foul, or inflammable air, 
which fill these spaces. Of these airs, 
the inflammable is the principal, which 
oozes from. the cracks and fissures 
of the rocks, and from heaps of smalk 
coal. The fixed and azotie airs, are 
yieided by the respiration of the miners, 
and by the burning of their candles, 
Modes have been lately introduced, of 
winding up the coals from the bottom of 
the pits, by smail fire-engines, instead of 
horses, and of conveying the coal to the 
wharfs along iren rail roads. ; 
~The quanuty of coal raised weekly, on 
the bank of the Birmingham Canal, and 
its several branches between Birning- 
ham and Wolverhampton, is computed 
at fifteen. thousand tons, of which about, 
eight thousand tons are sent to Birming- 
ham, and beyond; two. thousand tous 
foivebds Walvovene pton, and the Severn; 
and five thousand tons are supposed to 
be consumed in manufactures, towns and 
villages, near the Canal. ‘There are also 
about one thousand two hundred tons 
carried weekly upon the Stourbridge. and 
Dudley Canal, which makes, with. the 
eforegomg quantities, a total “of sixteen 
thousand two hundred tons of coal raised. 
weekly from the coal-pits of this district, 
to supply which consumption, upwards. 
of fifty acres of mine must be worked ans 
nually. Dr. Plott tells us that in’ his 
time 
