SALTER — A CHRISTMAS LECTURE OX COAL. 
67 
furnaces. There are one hundred and two mills and forges in the 
Staffordshire district. For this intonnation, also, I am indebted to 
Mr. Robert Hunt, of the Mining Record Office. 
We are not talking, however, of Staffordshii'e, but of coal mining in 
general, and now a word on the ventilation — the most important of 
all things for a mine after the water has been expelled. 
Without a furnace to create an upward draught in the one shaft, 
so that the air may rush down the other and travel through the mine, 
the work would be well nigh impossible. The way this precious air 
is made to circulate throughout, instead of merely going from one pit 
to another, is partly explained by our diagram, fig. 5, p. 64. The arrows 
point the way the air goes up one side of the workings, round the fur- 
ther end, nlong the working faces of all the galleries, and then back 
again nearly to the same point to the upcast shaft, U. There tha 
contaminated air, after passing the mouth of the burning fiery furnace, 
gains the uppei- world, and makes room for a better and purer element. 
The air is restricted to this course by the air-doors, which are marked 
as black lines in our plan, across the galleries. These are strongly 
framed doors, of iron chiefly, and are kept by boys, " trappers," as 
they are called, whose sole and solitary work it is to open and shut 
these trap doors whenever a train of waggons passes. A few words 
of converse with the " putter" lads, who bring the loaded skips down 
the "ways" — or it may be, quite as likely, a scuffle with them — are 
the only rehef these poor boys have (they are mostly very young) 
during the dark and solitary hours. They cannot afford a " low" or 
candle for the " trapper" boys ! 
In most of the important mines, a separate 'Svindway" or "airhead" 
is driven by the side of the galleries (or an air-tight wooden tube 
is carried along), exclusively devoted to air from the downcast shaft; 
and then, after supplying the miners in the stalls, finds its way back 
along the galleries, escaping every time an airdoor is opened. The 
same method is adopted in longwall work. But occasionally, as I 
learn from Mr. Smyth," they work two galleries side by side ; and use 
one of these for the incoming air, and the other for the return draught. 
Whichever mode is adopted, the principle is the same, viz. : to carry 
the ail" all round the mine, drawing it forcibly down one shaft and up 
another, at the other end of the system. Be it remembered the 
actual heat of the earth is much greater below the surface than above ; 
that choke-damp (an elegant term for cai'bonic acid) and other 
poisons too sometimes, are present in the mine ; and ventilation, 
whether by fans or furnaces, will be seen to be \4tal to the work. 
Any neglect in this important matter exposes the miners not only 
to the displeasure of the overseers, and the ill report of the govern- 
ment inspector, but to the positive danger of explosion from the foul 
gas, which is ever accumulating in the mine The fearful fire-damp, 
which has played so teriTible a part of late, is generated rapidly in the 
coal pit. It is carburetted hydrogen, the same gas which burns harm- 
lessly in our streets. It rushes out from many a fissure and dark 
chamber upon the miner, who, in spite of all the precautions taken for 
