A Firedamp-testing Safety Lamp.
Year: 1893

page_text: The decision of the Comptroller-General, of the 15th day of June 1894, allowed,
under Section 18 of the Patents, &c. Act, 1883, an Amendment of this
Specification
Date of Application, 25th Mar., 1893
Complete Specification Left, 22nd Dec., 13-Accepted, 10th Feb., 1894
PROVISIONAL SPECIFICATION.
A Firedamp-testing Safety Lamp.
I, ARTHUR HENRY STOKES, one of Her Majesty's Inspectors of Mines, of
Green Hill, Derby, in the County of Derby, do hereby declare the. nature of this
invention to be as follows:-
The object of the present invention is to provide miners' ordinary safety lamps
with an arrangement whereby when such lamps are in use they will indicate the
presence of smaller percentages of firedamp in the atmosphere than the ordinary
safety lamp will.
For this purpose a small lamp, burning alcohol or other volatile inflammable
liquid by means of a wick, is applied to the safety lamp, so that such wick is in
proximity to the wick of the safety lamp, and by adjusting the latter the wick of
the alcohol or other lamp can be ignited when necessary, the flame of the ordinary
wick being then extinguished, when the small blue flame of the alcohol lamp
will be at once affected if even a small percentage of firedamp is present.
When desired the main wick can be again ignited, and the alcohol wick can be
then extinguished.
The alcohol lamp may be a fixture attached to the main lamp, but it is preferably
made detachable, suitable means being provided for tightly closing the opening in
the main lamp to which the alcohol lamp is applied, when the latter is not in use,
and a tightly closing cover is provided for such alcohol lamp so that it can be
carried about when detached from the main lamp without loss of the liquid it
contains.
Dated this 25th day of March 1893.
ALLISON BROS.,
Agents for the Applicant.
A Firedamp-testing Safety Lamp.
I, ARTHUR HENRY STOKES, one of Her Majesty's Inspectors of Mines, of
Green Hill, Derby, in the County of Derby, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The object of the present invention is to provide miners safety lamps with an
arrangement whereby they will indicate the presence of smaller percentages of
firedamp in the atmosphere than the ordinary safety lamp will.
For this purpose a small lamp or tester, burning alcohol or other volatile
inflammable liquid by means of a wick, is applied to the safety lamp, so that such

page_text: wick is in proximity to the flame of the wick of the safety lamp, and by adjusting
the latter the wick of the alcohol or other lamp or tester can be ignited when
necessary, the flame of the ordinary wick being then extinguished, when the small
blue flame of the alcohol lamp will be at once affected if even a small percentage of
firedamp is present.
When desired the ordinary wick can be again ignited, and the alcohol wick can
be then extinguished.
The alcohol lamp or tester may be a fixture attached to the safety lamp, but it is
preferably made detachable, suitable means being provided for tightly closing the
opening through which the alcohol lamp or tester is introduced, when the latter is
not in use, and a tightly closing cover is provided for such alcohol lamp or tester,
so that it can be carried about when detached from the safety lamp without loss of
the liquid it contains.
But in order to enable my invention to be clearly understood, I will now proceed
to describe same by aid of the accompanying drawings, in which
Fig. 1 is a vertical section of the improved lamp, but with the small lamp or
alcohol tester removed therefrom.
Fig. 2 is a similar view of the lower part of the lamp drawn to a larger scale,
and showing the alcohol lamp or tester applied thereto.
Fig. 3 is an elevation of the alcohol lamp or tester with the closing cap or cover
applied thereto.
Fig. 4 is a vertical section of such alcohol lamp or tester without the closing cap
or cover.
The lamp bottom A is provided with a small tube b, passing through the oil-
vessel B, similar to a pricker tube, but of larger diameter. This tube is fixed
immediately behind the wick-holder of the oil flame, and terminates on a level with
the top of the wick-tube a. The bottom end of this tube terminates in a sunken
circular cavity in the bottom of the oil-vessel, such cavity being closed by a screw-
plug c when the tester is not in use. The upper portion of the tube b, or that
inside the lamp-glass C, and behind the wick-tube a, is protected by a spring-cap
or extinguisher g, which opens to receive the tube i of the alcohol tester E, and
closes upon its withdrawal. This is so arranged that the mouth g of the tube b is
opened by the insertion of the alcohol tester, and the tester cannot be withdrawn
without the tube being closed, the opening being firmly closed before the alcohol
testing-vessel is unscrewed from the thread of the plug cavity. From this it will
be seen that no flame can possibly pass down the tube b, even if the official using
the lamp omitted to replace the screw-plug c, after making a test for a low
percentage; but a further precaution is taken by attaching the screw-plug to the
lamp by means of a short chain. If the plug be loose, and the official had to put it
in his pocket when about to use the alcohol tester, he might forget to replace it,
but as it is permanently attached by a chain the plug hanging loose below the lamp
bottom would remind him of his omission.
The alcohol tester (Figs. 3 and 4) consists of a small cylindrical vessel E for
containing the alcohol, with a long wick-tube i screwed into the top of the vessel,
the connection being made by means of a circular brass plate e, on the under side
of which is a.leather washer to ensure a perfect fit. The wick-tube i is preferably
only 4 millimetres (0.16 inch) in diameter, and 55 millimetres (2.20 inches) long,
burning with two strands drawn from the ordinary round wick used for an oil-lamp.
The wick-tube i when not in use is protected from injury by a cap or covering
(Fig. 3) which, when placed over the wick-tube, is screwed to the alcohol vessel E.
The bottom of this cap is provided with a leather washer, securely covering the
air-hole of the alcohol vessel; the screw of the covering does not screw home or
touch the vessel, and in this way brings the screw pressure to bear upon the
leather washer. The two leather washers securely close the alcohol vessel, so that
it may be carried in the waistcoat pocket without fear of any of the alcohol
escaping.
The tester is charged with pure alcohol before being taken into the mine, and

page_text: when fully charged will burn for about four hours. This time permits of 120 tests
of two minutes each being made before the alcohol tester requires to be refilled.
The alcohol-flame is not intended to be used for the ordinary mode of examination
of the working-places, but should only be used after the oil-flame of the safety-lamp
has failed to detect gas; or in other words, examination with the alcohol-flame
commeures where the oil-flame breaks off.
The official using the lamp should first test with a reduced oil-flame, and if this
fails to indicate the presence of gas, he then raises his oil-flame to its normal
height. The screw-plug e is then withdrawn from the bottom of the lamp and the
alcohol tester made ready by unscrewing the capf and seeing that the wick has
been cut level with the top of the brass tube i; it is then inserted through the
bottom of the oil-vessel and screwed up. The top of the alcohol wick-tube i will
In a few seconds the
have opened the spring cap g, and appeared above the same.
heat of the oil-flame will have caused the alcohol to ascend the wick-tube and
become ignited, or the lamp may be held a little on one side, so that the light
from the oil-wick ignites the alcohol-wick. The alcohol-wick being lighted, the
oil-wick is drawn down into its wick-tube and so extinguished. We have then
only the small pale blue flame of the alcohol tester burning inside the lamp, and
by which the test is then made. Should no gas cap appear above this flame, the
atmosphere may be considered as virtually free from inflammable gas, or containing
below 0.50 per cent. of gas. Should a gas cap appear, its intensity of colour and
length gives the percentage of gas contained in the atmosphere.
The testing is materially facilitated by placing a small slip of black cardboard
round the front of the glass C, of sufficient depth to cut off from view the whole of
the alcohol-flame, and long enough to be held by the two standards of the lamp
when placed between such standards and the glass.
The test being made and noted, the oil-wick is raised by the pricker and bent
over until it touches the alcohol-flame, and is re-lighted by the same, the flame is
then adjusted to its proper light-giving height and the alcohol vessel and wick-
tube unscrewed. The withdrawal of the alcohol wick-tube i enables the automatic
spring-extinguisher 9 to close the opening of the insertion tube b inside the lamp,
and on the screw-plug c being inserted the lamp assumes its normal form, and is
again an ordinary safety-lamp with oil-flame. The cap or cover of the alcohol
wick-tube is screwed on, and the apparatus placed in the pocket until further
required for use, its weight being about 4 ounces.
In the case of air-currents containing 3 per cent. or more of inflammable gas, the
alcohol-flame is superseded by the ordinary oil-flame, inasmuch as that proportion
is clearly visible in ordinary oil lamps, and therefore the alcohol-flame is not used
for these high proportions, which could only be obtained by sacrificing the efficiency
of the test for the proportions lower than 3 per cent.
Any person accustomed to testing for gas in a mine will have little difficulty in
using the alcohol tester and ascertaining with approximate accuracy the percentage
of gas contained in the atmosphere of various parts of a mine.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination with miner's safety lamps of a small lamp or tester, burning
alcohol or other volatile inflammable liquid, and the wick of which is arranged in
elose proximity to that of the ordinary wiek of such safety lamp, substantially as
and for the purpose specified.
1. The employment with miner's safety lamps of a small lamp or tester, burning
alcohol or other volatile inflammable liquid, and which can be inserted within such
lamps so that the tester wick will occupy a position in close proximity to that of
the ordinary wick, and become ignited by the flame of the latter, when required to
be used, and can be withdrawn when its use is not necessary, in combination with
means for tightly closing the opening in the lamp through which the tester is

page_text: introduced, when same is not in position, all substantially as and for the purpose
specified.
3. 2. The alcohol lamp or tester constructed as described and shown in detail in
Figs. 3 and 4 of the drawings.
43. The improved combined safety-lamp and alcohol lamp or tester, constructed
substantially as described and shown in the drawings.
Dated this 12th day of December 1893.
ALLISON BROS.,
Agents for the Applicant.