364 
POHJLAR SCIENCE REVIEW. 
the fan through a culvert, at the top of which there is a large 
escape chimney with 4 large doors to allow the air to escape, 
should there he a blast, without injury to the fan. 
The accident was doubtless due to a blown-out shot, the 
effects of which have been known to travel 300 yards, and to 
blow down a door 80 yards distant. And though a fireman may 
carefully try for gas at the firing point, and it may not show in his 
lamp, when only one or two degrees below firing point, the dis- 
lodgment by the shot may add that small additional amount of 
gas requisite to make it explosive. In cases of this sort, it 
appears well-nigh impossible to guard against explosion so long 
as powder is used, in any inflammable coals. At Low Hall in 
Lancashire, the danger is reduced to a minimum by firing all 
the shots at night, which is adopted by Messrs. Cross Tetly’s in 
the Wigan 9-feet ; at Park Lane this coal is worked without 
powder ; at the Queen Pit, Pemberton, and at the Moss Pit it is 
not worked at all since the accidents at the respective places.* 
Gas is steadily and continually being given off by fiery coals, 
and the more perfect the ventilation, and the less it be interfered 
with, the more easily is it swept away ; at night when the ordi- 
nary operations are not going on, and doors being opened and 
shut, tubs ascending and descending, the ventilation is much 
more undisturbed, and the danger resulting from firing shots 
much reduced. At night also few lamps are in the pit, and the 
danger of the flame being forced through the lamp by the sound 
wave is much reduced. Great danger results from the employment 
of inexperienced persons, attracted, by the higher wages to be 
earned underground, from the plough and the spade, who are 
utterly ignorant of the use of the Davy lamp, and each one of 
whom is a source of danger to his fellow workmen. 
The Blantyre colliery is 15 miles from Glasgow, and consists 
of three shafts, No. 2 being rectangular 16 feet by 8, and 130 
fathoms deep; No. 3, 24 feet by 8, and 155 fathoms deep, and an 
upcast circular shaft 1 0 feet diameter, and 127 fathoms in depth. 
Though the mine has only been opened four or five years, 24 
statute acres have been opened out, by cutting levels up the dip 
of the coal, or down the dip, as suited the convenience of working 
best, and leaving pillars 22 yards square, which system is called 
in Scotland “ stoop and room,” the stoops being the pillars. It 
will readily be understood that the difficulties of properly ven- 
tilating such miles of passage must be very great if not insup- 
erable. Mr. Pickard, the agent of the Miners’ National Associa- 
• Five coal-seams were ventilated from these pits, the Wigan 4-feet mine 
taking 48,700 cubic feet of air; the 9-feet, 15,200; the King coal and 
cannel, 50,580 ; the Orrel 4-feet, 34,360 ; the Orrel 5-feet at Arley Main, 
43,630. 
