The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1886-10-16 00:00:00

ELECTRIC SAFETY LAMP for MINERS.

A meeting of the North of England Institute of
Mining and Mechanical Enginaers was held on Satur-
day at Newcastle-on-Tyne, Sir IsaacLowthian Bell in
the chair.
Mr. J. W. Swan read a paper upon "A portable
electric safety lamp for miners." At a previous meet-
ing of the institute in 1885 Mr. Swan exhibited his
electric lamp, which at that time possessed no means
of indicating the presence of fire-damp. This fact
was commented upon at the time, and Mr. Swan, in
reply, said h hoped to be able to combine a fire-damp
indicator with the lamp. At Saturday's meeting Mr.
Swan announced that he had succeeded in this object,
and exhibited two lamps with fire-damp indicators
attached. He pointed out several improvements which
he had made in the lamp since the 1885 meeting, re-
ducing it in size and weight, and making it more like an
ordinary miners' lamp in general form. With the oil
lamp, he said, safety against explosions had only been
procured at the cost of diminished light, and no safety
lamp existed except the electric safety lamp which
would give a good light and at the same time a safe
one. The two grsiat sources of danger in coal-mines,
fire-damp and falls of roof and sides, were both
guarded against by the electric lamp, the danger from
tire-damp by the light being entirely out of contact
with the atmosphere of the mine, and the danger
from falls by the better light procured. He believed
there could not be I) doubt that the electric lamp in
the form in which he now presented it possessed these
advantages, and that its introduction into mines was
merely a question of convenience and cost. He had
bestowed much thought upon these points with a view
to bring them within practical limits. As far as he
could judge from the small experimental use of the
lamps he now exhibited, they would neither be very
troublesome nor very costly. Five-horse power would
keep 1000 lamps going—that was to say, 500 on the
charging circuit and 500 in use in the mine. The cost
of lamp renewals would be the heaviest charge. That.
he reckoned, would amount to 2d. per lamp per week.
Where the number of lamps was considerable
id. or 11d. would cover the cost per lamp for wages
for keeping the lamps charged and in order. Another
id., making 4d. per week, would cover the charge
for interest on the capital outlay for cost of lamps
and other plant. With regard to the important
addition which he had made to the lamp, the fire-
damp indicator, Mr. Swan said he had made it in
three forms. Two of these act on the same principle
as Liyeing's fire damp indicator. A spiral coil of thin
platinum wire is arranged so that it can be heated to
a low red heat by switching through it the current
generated by the lamp battery. If this heating takes
place in an atmosphere in which tire-damp is present
the wire becomes hotter than when heated in the pure
atmospheric air. In one form he had followed Mr.
Liyeing's idea of haying a comparison wire shut up air
tight in a glass tube containing pare air; in another
he had deviated from Mr. Dyeing 's construction. In
the third form of indicator there is a platinum wire
within a small tube. The means of turning off the
current from the lamp battery to heat the wire is as
before, but here the hot wire is employedonly to effect
the combustion of any fire-damp that may be present,
with a view to the production of a partial vaccum re-
sulting.from the condensation of the watery vapour of
the burnt gases. The degree of vacuum or shrinkage
is shown by the rise of the liquid in an adjacent
gauge tube, and from this the exact percentage of
fire-damp present in the air may be ascertained.
This form of test is also and necessarily made in a
closed vessel. The hot wire is completely cut off
from contact with the outer air. For the simple
detection of the presence or absence of firedamp the
two wire forms are quite efficient down to per cent.,
but for exact measurement of the quantity, even
down to per cent., the liquid indicator is the more
efficient. Both are instantaneous in their action as
mere indicators, but for actual measurement from
two to five minutes are required for each observation.
"1- The instrument exhibited to the meeting was
shown attached rigidly to the body of the lamp, but
Mr. Swan intimated that he also makes it in another
form, which allows of an indicator, apart from the
lamp, being swept along the roof of the mine when
searching for gas.
A vote of thanks to Mr. Swan was heartily
accorded.