f 501 ] 
USEFUL PROJECTS, &c. 
Sir Humphrey Davy's Discovery 
of a Method Jor preventing 
Explosions from Fire 
Damp in Mines. 
the 
HE numerous fatal effects of 
explosions in the collieries 
which have lately engaged the 
public attention, having induced 
the eminent chemical philosopher 
above-mentioned to turn his stu- 
dies to the subject, the result has 
been a very curious and valuable 
paper communicated to the Royal 
Society, and printed in their 
Transactions for 1815, from 
which the following extract, chief- 
ly referring to the practical part, 
has been made : 
«« After ascertaining, by avariety 
of experiments, the combustibi- 
lity and explosive nature of the 
fire-damp in mines, and finding 
that a mixture of this gas with 
air would not explode in metallic 
canals or troughs when their dia- 
meter was less than one-seventh 
of an inch, and that explosions 
- would not pass through such ca- 
nals; also that explosions would 
not pass through very fine wire 
sieves or wire-gauze ; Sir H. D. 
comes to the following inference. 
‘< [tis evident, then, that to pre- 
vent explosions in coal mines, it is 
only necessary to use air-tight lan- 
terns, supplied with air from tubes 
or canalsof small diameter, or from 
apertures covered with wire-gauze 
placed below the flame, through 
which explosions cannot be com=- 
municated, and having a chim- 
ney at the upper part, on a si- 
milar system, for carrying off the 
foul air; and common lanterns 
may be easily adapted to the pur- 
pose, by being made air-tight in 
the door and sides, by being 
furnished with the chimney, and 
the system of safety apertures be- 
low and above. 
« The principle being known, it 
is easy to adopt and multiply prac- 
tical applications of it. _ 
«The first safe-lantern that [had 
constructed was made of tin-plate, 
and the light emitted through four 
glass plates in the sides. The air 
was admitted round the bottom of 
the flame from a number of me- 
tallic tubes of 3 of an inch in dia- 
meter, and an inch and 4 long.— 
The chimney was composed of 
two open cones, having a com- 
mon base perforated with many 
small apertures, and fastened to 
