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tant facts respecting fire-damp, choke-damp, atmospheric air, 
combustion, rarefaction, and other agents in those frightful 
accidents against which they have to guard. Still less have 
I either nostrum or secret to reveal. 
But in the course of preparing two or three such lectures, 
not yet delivered, some circumstances presented themselves, 
which, however, singly, well known or obvious, have scarcely 
met, in connection with each other, with all the attention which 
they deserve. The report of Sir Henry De la Beche and 
Dr. Playfair,* it is true, is so able and so comprehensive, that 
it supersedes much which I might otherwise remark. But 
several minute and accurate accounts of explosions of later 
dates have appeared since their general report or essay was 
written. These enable me to draw inferences from a greater 
number and variety of well-recorded instances than they had 
then before them. Many circumstances are only incidentally 
mentioned, or to be gathered from casual remarks, and are 
therefore by no means plain on once reading. The result 
on my mind is a persuasion that tendencies to a dangerous 
condition exist in mines reputed to be comparatively safe, 
and that these tendencies are so numerous and vary so 
suddenly, that no degree of precaution of one kind can 
exclude the necessity of attention to others. f 
The appointment of inspectors of coal mines, and the sub- 
jecting them to regular inspection, will, we may reasonably 
hope, diminish the frequency and the extent of these disasters. 
I do not anticipate that they will ever entirely cease. But 
this step, the appointment of inspectors, ought rather to in- 
crease than lessen the interest which scientific bodies like this 
should take in the discussion of past, with a view to the pre- 
vention of future, misfortunes. The same records which 
* Collieries' Report, 1847, p. 4. 
f I use the term " mine," though " pit" is more common, because the latter 
would cause some ambiguity, since " pit" is in several of these accounts used 
also for " shaft." It is so in u Collieries' Report," pp. 47, 48, 49. 
