74 The Davy —Steam-Engines in Cornwall. 
I think it extremely hard that our feelings should be lacerated 
by the obstinacy of prejudice or error in neglecting to use ‘the 
Davy” in mines subject to the fire-damp.—The accident at the 
colliery near Durham is a sad example of the too palpable truth, 
that we have yet much to encounter in its universal adoption. 
Much pains have been taken indeed, by persons who ought to 
have known better, to unhinge the mind in the belief of its ab- 
solute safety. I am ready at any time to prove, at the risk of 
my life, that it yields a perfect security to the miner. I have 
lately had a most decided proof of this in one of the collieries 
at the Hurlet near Paisley. The mine-in question had been 
abandoned wpwards uf twelve months, by reason of the accumu- 
lated and still accumulating fire-damp. The experiment afforded 
a spectacle of the most beautiful and impressive kind,—The gra- 
dual approach to the confines of the explosive waste was indi- 
cated by the included flame of the lamp presenting a lengthened 
spire, so as ultimately to brush the dome of the cylinder ;—on 
passing this boundary the wire-gauze hecame suddenly red hot, 
and the flame of the wick was enveloped by the apparition of a 
foreign flame which continued to fill the cylinder—a candle 
here might have proved as destructive as any upon record ; for in 
an extent of three or four acres, it exhibited from the floor up, 
an explosive medium. These mines had some years ago to re- 
cord an accident by which seventeen human beings were con- 
signed to eternity. 
There was a phenomenon here which forcibly impressed me, 
The degrees of the fire-damp and explosive measure, as indicated 
by “ the Davy,” proved that they were not uniform in diffusion, 
but existing im strata or clouds throughout the atmosphere of 
othe mine. 
From some recent experiments, on the subject of which I may 
again address you, I am of opinion that the principle of safety 
in this wonderful instrument is to be attributed to the depolari- 
zation of the flame by the wire-gauze. 
I am respectfully, sir, 
Your most obedient servant, 
Greenock, July 22, 1817. J. Murray. 
PRESERVATION OF MEAT. 
Don Eloy Valenzuela, curate of Bucaramanga in South Ame- 
rica, has discovered that meat may be preserved fresh for many 
months by keeping it immersed in molasses. 
STEAM ENGINES IN COKNWALL. 
According to Messrs.’ Lean’s Report for May and June, the 
following were the respective quantities of water lifted one foot 
high 
, 
: 
: 
: 
“ 
4 
