20 H. C. Hovey—Danger from Coal-dust in Mining. 
and the conclusion was plainly justifiable that the flame of the 
explosion had not extended thus 
The walls of the galleries bad been swept clear of timber, 
and presented the appearance of having been brushed with a 
broom. Volumes of coal dust had been driven along by the 
the levels, into which the party sank to their knees. It was 
found that clouds of the finer particles had been carried to the 
shaft and beyond it into the main north level, where a second- 
ary explosion had taken place, demolishing the « lamp cabin,” 
burning the horses between the shaft and the cabin, and fatally 
burning the man aye business it was to clean and distribute 
safety lamps to the miners. 
Secondary eaplocions caused by extracted or ie geeagl gas 
are nearly always in the vicinity of the first one; but her 
a case where the second was half a mile from the first, ah & an 
intervening space of at least a quarter of a mile known to have 
been free from flame, and presumed to be free from gas, be- 
cause men were in it with lamps Gisch showed no indications 
of its presenc 
Water was : daneiwualy trickling down the shaft, and the 
ee for some distance around were very wet, hence the dust, 
soon as it touched the wet walls would be made innocuous; 
bik the fine, dry particles of carbon that were driven on into 
the lamp cabin were ready for ignition. It had been the cus- 
s occasion it seems to be certain that the ignition of 
the ae dna caused a second explosion; and it is probable 
that the same agency was efficient in producing, or at least aug- 
menting, the subsequent explosions that made it necessary to 
— the whole mine. It was as if the woncia of a gun were 
compo an inflammable material, which on firing the 
charge doubled its effect. It should also be noted that, as a 
pen the Albion mines were very dry, except in portions 
though confessedly not well understood, is worthy of attention 
from scientific men, and perhaps none the less so for that very. 
reason. 
7 
eae 
be ere a ee 
