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lupton: safety lamps. 
I will now describe some of the modifications of the Davy, and 
the first of these is the Clanny lamps (see fig. 2), called, like most 
other lamps, by the name of the inventor. This only differs from 
the Davy in having a glass cylinder substituted for the lower part of 
the gauze cylinder. There are two great advantages gained by this 
improvement, great increase of light, taking the light of a sperm 
candle as 100, the Clanny will give 47 and the Davy only 18 
(according to Marsaut). The second advantage is that it is easily 
carried in a strong current of air which would extinguish a Davy 
lamp. These great advantages have caused the Clanny to be largely 
used. There are, however, three disadvantages as compared 
with the Davy : The glass may be cracked and broken if it is heated 
by holding the lamp on one side or by water falling on to it ; it is 
more complicated and it is an easy matter to put the parts together 
in such a way that it is unsafe, and yet this may not be detected ; 
3rd, it is possible to cause an explosion with this lamp if the flame is 
drawn down for gas trying, and it is raised into an explosive mixture 
and rapidly withdrawn, an explosion may take place inside which 
will pass through the gauze and fire the gas outside ; this is owing 
to the glass cylinder holding a chaige of explosive gas which is shot 
out with great violence against the gauze. Such an accident cannot 
take place with a full flame, because the products of combustion 
partly fill the lamp and diminish the force of any explosion that 
may occur ; therefore in using a Clanny a full flame should be in the 
lamp when testing gas. 
The Stephenson Lamp (see fig. 3) is constructed by taking a 
Davy lamp of large diameter, and putting inside it, a glass chimney, 
on the top of the chimney is a copper cap perforated with small 
holes ; the air for the flame enters the lamp through an external brass 
ring below the glass, in this ring are perforated small holes, which 
regulate the current of air entering the lamp, the air then passes 
through the gauze and under the glass ; the amount of air entering 
the lamp is thus regulated by the openings above and below to the 
amount required for combustion. If gas enters the lamp it uses 
up all the oxygen and the lamp is extinguished. This lamp may 
therefore be put into an explosive mixture and will, under ordinary 
