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all circumstances."* That " safety lamps, properly used, 
do effect much security in the working of coal."f Dr. 
Playfair again expresses his " conviction that the accident 
at Jarrow would, in all probability, not have occurred, had 
lamps been employed instead of candles" in the Low Main.J 
I leave to colliers the question between higher wages, with 
greater danger, and lower with safety; to coal masters, 
whether to allow all or any part of the increased wages 
or allowances claimed for the use of lamps. But the testi- 
mony in favour of lamps is not confined to theorists or men 
of science. A workman at Jarrow, after making the usual 
complaint of the Davy being " so dark," is asked, " You 
have had long experience in pits; did you ever know an 
accident take place where the Davy was fairly used ?" He 
answers, " Never."§ 
We have further some very interesting facts, furnished not 
by a philosopher writing in his study, but by a viewer at 
Walker Colliery, near Newcastle-on-Tyne. On November 
13th, 1846, when approaching a slip dyke, a mass of coal 
was displaced, weighing about eleven tons. On the displace- 
ment of this block, and the discharge of fire-damp that 
followed, being observed by the two men working in the 
drift, they immediately extinguished one lamp, (the other 
having been put out by the accident,) informed the other 
men in the pit, and retired to the shaft. The air rendered 
foul in an instant was ascertained by subsequent measurement 
of the passages to which it extended to be more than 40,000 
cubic feet. A second violent discharge took place from near 
the same spot on the 10th December. Judicious precautions 
had been taken to prevent mischief. While the men were 
breaking down a portion of roof, to enable the tram-road to 
be carried up, the " danty" or broken coal in the slip of the 
dyke, above where a bore-hole had just been made, was 
* Report, 1847, p. 9. t P. 11. } P. 17. § P. 19, Emanuel Dufty. 
