S92 Mr Murray’s New Safety -Lamp. 
3. Description of a Nezo Safety-Lamp for Mines. By J ohi^' 
Murray^ Esq. F. L. S. and Lecturer on Chemistry. Com- 
municated by the Inventor. 
My new safety-lamp, which is represented in Plate X. 
Fig. 2. consists of two concentric cylinders of thick glass, the 
space between being filled with water through a pipe at top, and 
represented in the figure, having an air-escape aperture on the 
opposite side. Over the flame of the wick is a bell or funnel, 
with a double recurved pipe issuing from its summit, and passing 
below the lamp, terminating immediately under a single central 
aperture. Here, the products of combustion are discharged, 
(the excess is of course disengaged by the usual aperture at the 
top of the cylinder), and mingled with the explosive atmosphere 
rising from below, and passing to the flame of the lamp. This 
is again mixed more intimately at its immediate ingress, where 
it passes through the apertures represented on each side of the 
lamp. The rest may be inferred from a simple inspection of the 
figure, in which two of the ribs that fence in the outer cylinder 
(a guard from external injury) are supposed to be removed, in 
order to shew the internal arrangement to better advantage. 
By a circular band of lead affixed to its base, the instrument 
will always fall vertically; and should it accidentally fall on its 
side, it will immediately recover its upright position. 
The water will not spill in any condition of the instrument, 
for the resistance of the atmosphere will prevent this. It is 
shewn lower in the cylinders than it ought to be, in order to be 
clearly represented- Its expansion is compensated for. The 
water will preserve the inner cylinder of an equable temperature. 
Hedged in by water, external injury may only affect the outer 
wall ; but granting that the instrument is crushed to atoms in an 
explosive atmosphere, the worst that can happen is the extinc- 
tion of the flame within by a flood of water. 
I see no necessity for shielding the inner cylinder by metallic 
bars, because explosion cannot take place within. 
The lamp is a self-regulator, and takes care of itself ; for, as 
the quantity of azote, &c. will be in the ratio of the quantity of 
the disarmed explosive mixture, and consequent elongation of 
the spire of flame, so soon as it amounts to a maximum extinc- 
