USEFUL PROJECTS, &e. 
much larger quantities than by the 
small tubes. In this arrangement 
there is so free a circulation of 
air, that the chimney likewise may 
be furnished with safety canals. 
‘*¢T havehadlamps made for this 
kind of lantern which stand on 
the outside, and which may be 
supplied with oil and cotton with- 
out any necessity of opening the 
lantern; and in this case the chim- 
ney is soldered to the top, and the 
Jamp is screwed into the bottom, 
and the wick rises above the air 
canals. 
“Thave likewise had glasslamps 
with a single wick, and Argand 
Jamps made on the same principle, 
the chimney being of glass cover- 
ed with a metallic top containing 
the safety canals, and the air en- 
tering close to the flame through 
the circular canals. 
‘<The third kind of safe lamp, or 
lantern, and which is by far the 
most simple, is a close lamp or 
lantern into which the air is ad- 
mitted, and from which it passes, 
through apertures covered with 
brass wire gauze of 74,5 of an inch 
in thickness, the apertures of 
which should not be more than 
+i Of an inch ; this stops explo- 
sions as well as long tubes or ca- 
nals, and yet admits of a free 
draught of air. 
** Having succeeded in the con- 
struction of safe-lanterns and 
lamps equally portable with com- 
mon lanterns and lamps, which 
afforded sufficient light, and which 
bore motion perfectly well, I sub- 
mitted them individually to prace 
tical tests, by throwing into them 
explosive atmospheres of fire- 
dampandair. Bythenaturalaction 
of the flame drawing air through 
the air canals, from the explosive 
503 
atmosphere, the light was uni- 
formly extinguished ; and when 
an explosive mixture was forcibly 
pressed into the body of the lamp, 
the explosion was always stopped. 
by the safety apertures, which may 
be said figuratively to act as a sort 
of chemical fire sieves in separating 
flame from air. 
«When the fire-damp isso mixed 
with the external atmosphere as 
to render it explosive, the light in 
the safe-lantern or lamp will be 
extinguished, and warning will be 
given to the miners to withdraw 
from, and to ventilate that part of 
the mine. 
“If itbenecessary to bein apart 
of the mine where the fire-damp 
is explosive, for the purpose of 
clearing the workings, taking away 
pillars of coal, or other objects, 
the workmen may be lighted by a 
fire made of charcoal, which burns 
without flame, or by the steel-mill, 
though this does not afford such 
entire security from danger as the 
charcoal fire. 
‘Tt isprobable, that when explo- 
sions occur from the sparks from 
the steel-mill, the mixture of the 
fire-damp is in the proportion re- 
quired to consume all the oxygen 
of the air, for it is only in about 
this proportion that explosive mix- 
tures can be fired by electrical 
sparks from a common machine, 
“As the wick may be moved 
without communication between 
the airinthe safe-lantern, or lamp, 
and the atmosphere, there is no 
danger in trimming or feeding 
them ; but they should be lighted 
in a part of the mine where there 
is no fire-damp, and by a person 
charged with the care of thelights; 
and by these inventions, used with 
such simple precautions, there ig 
