141 
Lancashire, Warwickshire, and Monmouthshire, five districts 
as remote from each other as could be wished if we had made 
a selection. (See table.) The thickness of the beds varies 
from four or five to thirty feet. (See table.) The coal at 
Oldbury is much shattered.^ At Riscaf and at CoppullJ it 
is very hard, so that it is considered necessary to blast it with 
gunpowder. At Haswell, also, though the report does not 
mention it, gunpowder was employed ; also at Jarrow.§ 
Let us turn to some general remarks. Pits long and ex- 
tensively worked are justly considered more dangerous than 
such as have been recently opened. Yet a new pit is not 
necessarily safe. Deep pits are generally considered more 
unsafe than those nearer the surface.! There is little reason 
why it should be so, unless where depth implies old or exten- 
sive working. But mere depth of shaft is favourable to 
ventilation where cupolas or furnaces are employed, as sup- 
plying a long column of rarefied air. The depths reported 
vary from 300 yards at Haswell and at Jarrow, to 130 yards 
and 75 yards at Darley. Some seams are much more fiery, 
that is, give out much more carburetted hydrogen than others. 
These undoubtedly are the most dangerous, and require es- 
pecial care. But I find the character of the seam at Haswell 
to be ‘Mess fiery than many .'’If At Darley “but little fire- 
damp.”'^* “No great quantity of Gas.”ft So that a mine 
bearing a tolerable character may be the seat of repeated 
explosions. 
That habit, and comparison with yet greater risks, can 
lead men to apply very gentle terms to the degree of danger 
in their own case, is shown in the instance of Jarrow, re- 
specting which it is said, — “ Not reputed to be very fiery, but 
the quantity of gas is very considerable.”tt In this “ not 
* Report, 1847, p. 44. f Idem, p. 23. f P. 48. § P. 22. 
II Edinburgh Review, No. clxxx, April, 1849. 
^ Philosophical Magazine, vol. xxvi., p. 19. ** Report on Darley, p. 10. 
tt Ditto, p. 1. Report, p. 15. 
K 
VOL. III. 
