Improvements in Miners' Safety Lamps.
Year: 1894

page_text: Date of Application, 29th Dec, 1894
Complete Specification Left, 28th Oct, 1895-Accepted, 14th Dec., 1895
Improvements in Miners' Safety Lamps.
1, PIERRE GRANDJEAN, of 94, Rue d'Allemagne, Paris, in the Republic of
France, Engineer, do hereby declare the nature of this invention to be a
follows:-
My invention relates to miners' safety lamps.
It is well known that in the Davy lamp the flame surrounded by wire-gauz
situated above the oil reservon in a protecting cage of iron rods, and that in the
Combes lamp the flame is surrounded with a thick crystal surmounted by a chimney
provided with hermetical wire-gauze.
My improved safety lamp is constructed with regard to the two kinds of lamps
above mentioned, the object being to increase the illuminating power of the
flame and the safety of the lamp, and to effect an economy in the consumption of
the oil
My lamp as I propose to construct it is an improvement on the Combes lamp.
It comprises a cylindrical chamber forming the oil reservoit and surmounted at the
centre by a flat wick burner and by a cage having vertical bars which are screwed
into a ring on the lamp and which has at the top a platform serving in combination
with the glass hereinafter described to support the wire-gauze casing and another
cage with vertical bars. This cage is provided on the top with a hood or cover to
which is attached the hook for suspending the lamp.
My lamp is distinguished by the following essential features:-
In order to increase the power of the flame and economize the oil, I oxidize the
combustible gases by means of an drawn through small tubes or passages passing
vertically through the oil reservoir and closed at their lower ends by wie-gauze
soldered to the bottom of the reservoir, and which prevent any communication
There
between the interior of the lamp and the inflammable gases in the mine.
are besides four holes made in the bottern of the reservon and corresponding with
inclined tubes passing through the oil and extending to the outer side of the body
of the lamp and serving to keep the base of the lamp cool.
Near the lower end of the conical chimney I aliange a double wine-gauze cap
or collar and I cover the chimney with a truncated comical casing the base of
which is provided with holes and lined in the interior with wire-gauze. In a convex
chamber of the chimney the gases of the lamp become heated, thereby increasing
the heat in consequence of the non-cooling of the gases of combustion which rise
in the central chimney. In this manner I therefore effect a considerable economy
in the consumption of oil without any interference with the draught At the same
time (and this is a very important and novel result) I increase the safety of the
lamp by preventing the inflammable gases in the mine from reaching the burner
by the inter position of the said cap or collar
The conductibility of the wne-gauze cools the gases and renders them powerless
to act upon fire-damp which might pass within the wue-ganze covering of the
chimney.
All the upper part of the apparatus is separated from the outer atmosphere.by
a casing formed of a double thickness of wire-gauze
To increase the lighting power of my lamp I use in place of the crystal tube of
the Combes lamp a crystal tube of lens like longitudinal section which very
considerably magnifies the image of the flame and thereby increases the

page_text: illuminating power of it as in a magic lantern. The glass of this tube may be
smooth or it may be channeled, striated, or corrugated longitudinally upon its
outer face with the object of refracting and diffusing the light.
With the same object I can adapt to the bars of the protecting cage a polished
metal reflector and 1 fix upon the body of the lamp a collar carrying a frame in
which is placed a bi-concave or other lens arranged opposite the reflector which so
much increases the iluminating power as to enable the mine to closely examine
fissures in the mine which in certain cases secrete fire-damp
To prevent the lamp from being tampered with by the miner or other workman,
that is to say, to prevent any opening of the lamp due to negligence, imprudence
oi malice, arrange beneath the bottom of the oil reser von a lock of segmental
shape soldered to the bottom and consisting of two plates between which works
a plate or shutter which, when the loch is closed by means of a key, covers a
screw-threaded pm without unscrewing which it is impossible to open the lamp
This lock after filling and timuning the lamp is closed by means of n hey with
a double bit and is only reopened upon its return to the lamp-lighter.
Instead of this arrangement I can cover the sciow-threaded pin with a plate
hinged to the oil reservoir and which atter the lamp has been filled 18 soldered
to the bottom of the reservon by its free end and is unsoldered by the lamp-
lighter.
For auners, and conductors of trains or cages I can provide lamps with
magnifying glasses, colored on not, so as to signal their approach from a distance.
Dated this 29th day of December 1894.
G. F. REDFERN & Co,
4, South Street, Finsbury, London, Agents for the Applicant.
Improvements in Miners' Safety Lamps.
I, PIERRE GRANDJEAN, of 94, Rue d'Allemagne, Paris, in the Republic of
France, Engineer, 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 :-
My invention relates to miners' safety lamps.
It is well known that in the Dasy lamp the flame is surrounded by wire-gauze
situated above the oil reservoir a protecting cage of non iods, and that in the
Combes lamp the flame is surrounded with a thick crystal surmounted by a chimney
provided with hermetical wire-gauze.
My improved zalety lamp is constructed with regard to the two kinds of lamps
above mentioned, the object being to increase the illuminating power of the flame
and the safety of the lamp, and to effect an economy in the consumption of
the oil.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawings, m which :-
Figures 1 and 2 are respectively an elevation and a plan of one form of my
improved safety lamp, in Figure 1 the wire gauze casing of the crystal tube 18
supposed to be removed:
Figure 3 is a vertical section of this lamp on the line 1, 2, 3 of Figures 4
aud 5.
Figure 4 is a plan of the oil reservoir:
Figure 5 is a view of the underside of the lamp:
Figures 6 to 16 are views of details which are hereinafter referred to.
Figure 17 is an elevation of a miner's lamp constructed according to my invention
with slight modifications which reuder it very practical.

page_text: Figure 18 is a section on the line 5-6 of Figure 17 the lamp being viewer
below.
Figure 19 is a vertical section on the line 7, 8, 9 of Figure 18:
Figure 20 is a horizontal section on the line 10-11 of Figure 17.
In all the figures the same letters of reforence indicate similar or corresponding
parts.
My lamp as I propose to construct it is an improvement on the Combes lamp.
It comprises a cylindrical chamber A forming the base of the lamp and the oil
reservoir and surmounted at the centre by a Hat wick burner A' and by a cage
having vertical bars g the said cage being screwed on a screw-threaded ring A³
on the chamber A and having at the top a platform g' serving in combination
with the glass to support the chimney C and the wire-gauze casing and also
another cage o with vertical bars. This cage o is provided on the top with a
hood or cover o' having a ring to which is attached the hook for suspending
the lamp.
My lamp as represented in Figures 1 to 16 is distinguished by the following
essential features
-
In order to increase the power of the flame and economize the oil, 1 oxidize the
combustible gases by means of air diawn through small tubes or passages a,
(Figures 3 and 4) passing vertically through the oil reservoir and provided at their
lower ends with wine-gauze coverings a soldered to the bottom of the reservoir,
and which prevent any communication between the interior of the lamp and the
inflammable gases in the mine, these tabes a, open freely at each side of the
buiner A'.
For the purpose of preventing the heating of the oi! I arrange four inclined
tubes b, which extend from the bottom of the reservoir and pass though the oil,
to the exterior of the body of the lamp as shewn in Figures 1, 3 and 5.
The lamp is provided with a suitable arrangement for raising or lowering the
This
wick of the burner and for removing therefrom the carbonised portion
arrangement may consist of a metal wire p, which passes vertically through the
body of the lamp through a tube and is suitably bent at p'; beneath the reservou
is a handle p³ foi operating the wne (Figures 3, 4 and 5).
The chimney C (Figures 3 and 6) which surmounts the burner A¹ is provided
with a double wire gauze collar e' (Figure 6) consisting of a base c' and a truncated
conical part c
The chimney C is covered with a casing d the truncated conical
base d' (Figures 3 and 7) of which is provided with holes d², and lined with wine
gauze the upper part of the casing d is formed of wire gauze
The external casing e, (Figures 1, 3 and 8). mcluding both the vertical
cylindrical part and the part forming the covet, is formed of a double thickness
of wire gauze.
In the cage g, screwed onto the reser von A 15 adjusted the crystal glass f
(Figure 9) which may be cylindrical or of longitudinal lenticular section the latter
form having for object to magnify the image of the flame.
I can also make use of
glasses (Figure 10) channelled, striated, or corrugated longitudinally.
I sometimes adapt to the rods of the protecting cago g, of the glass, a reflector h
of polished inetal, Figures 11 and 12. In Figure 11 the reflector is concave and
15 hooked by its edges to two of the 1ods g. In Figue 12 the reflector comprises
two surfaces h', ', carried by a sheet of metal the bent edges of which are hooked
to two of the rods g. Either of these arrangements prevents the diffusion of light
and allows it to be concentrated on a particular spot
The effect of the reflector can be heightened by the employment of a double
convex lens, (Figures 3 and 14) placed opposite to the reflector and carried in a
frame or holder formed integral with a collar i (Figures 3 and 13) which surrounds
the reservoir A of the lamp.
The cage is sometimes surrounded by a casing of wire gauze k fixed by a
bayonet joint on the platform g'.
From this construction it will be seen that while air can be freely supplied to

page_text: the burner by the air tubes a, fire damp cannot penetrate into the lamp owing to
the wire gauze coverings a' with which the an tubes are provided, it the lamp is
in an atmosphere of fire damp pure air can no longer reach the burner which
consequently is extinguished. the products of combustion from the burner A' are
collected under the collar or beneath the casing d and there maintain a relatively
bigh temperature which assists in effecting perfect combustion combined with great
economy. Furthermore by my improved construction I increase or rather
completely ensure the safety of the lamp by preventing the inflammable gases in
the mine from reaching the burver.
By the use of a glass of lenticular section in combination with the reflector h
and the lens the lighting power of the lamp is considerably increased.
In order to obtain the maximum of light with the smallest consumption of wick
the wicks are prepared as follows -1 dissolve about two grammes of bicarbonate
of soda in about one hundred grammes of water and I immerse the wicks in this
liquid for about a quarter of an hour. the wicks are then withdrawn, drained,
pressed and died either by exposure to the atmosphere or in a stove. The wicks
are then ready for use and will last for a considerable time.
To prevent the lamp from being tampered with by the miner or other unauthorised
person I employ the arrangement illustrated in Figures 3, 5 and 16.
T
The cage prevented from being unscrewed by a screw threaded pin / screwed
into a tube passing through the reservoir A, the end of the said pin taking into
one of a number of notches with winch the base of the cage g is provided To
release the cage the pin must be unscrewed therefrom and to prevent the più
from being withdrawn by an unauthorised person I fix, by solder or otherwise, to
the bottom of the lamp a lock m, having a leyhole m³, m³ is another opening
formed opposite the squate head of the pin 7 By turning the key a plate or
shutter m is brought beneath the head of the più completely covering the
opening maud preventing access to the said pin. By moving the plate m³ the
opening m³ is uncovered and the pin Z can be operated.
I sommetunes employ the arrangement shewn in Figures 16 and 19 in which the
lock is replaced by a plate a hinged to the oil reservon at ' and adapted to cover
the opening leading to the pin in which position the plate 15 soldered to the
body of the lamp so that to gam access to the pin 7 it is necessary to unsolder the
said plate n.
A modified form of lamp which I prefer by reason of its simple constinction,
good lighting results, economy and the absolute safety it secures is illustrated in
Figures 17, 18 19 and 20 of the accompanying drawings and in relation to the
lastening aangement also in Figure 16
.
The part A which comprises the foot of the lamp and the oil resei von 18 provided
on its underside with a bent tube a² open at both ends and filled with metal
shavings a or provided with wie gauze to present the admission of fire damp
from this tube a³ issue a number of other tubes a which conduct the air admitted
into a³ and into the tube a² to the burner A¹ the tubes a pass through the oil and
dispense with the use of the cooling tubes b shewn in Figure 3.
I employ a cylindrical glass fand I construct the chimney entirely of wire
gauze arranged as shewn in Figme 19 At the centre is the cylindrical part ³
the lower edge c' of which rests upon the glass faud is clamped by the shoulder g
of the upper cage; the part c³ is enclosed in a tineated comical jachet d* which is
closed at the top by a sheet of we gauze. At the base this casing 18
duplicated by a second casing d of wie ganze the object of which is to prevent
the admission of any air from outside the casing d'. This latter casing is itself
enclosed within another casing e of wie gauze having a wire gauze top e. Above
this last casing e is a casing of thin sheet metal provided with two series of sinall
holes e, one at the upper part and the other at the lower pait.
In practice I have found that this construction of lamp gives absolute safety,
fire damp cannot reach the buiner A¹ either though the air tubes a owing to the
metal shavings a³ of the supply tube a², or through the wire gauze casings e, e', dª, ‹³

page_text: and, as they are arranged and combined. On the other hand by reason of the
arrangement of the wire gauze casing e³, d', d' I entirely prevent the flames of the
bunner from smoking and extending too far. Further by employing my wicks
prepared with bicarbonate of soda the formation of excrescences or wastors is
presented whereby the wear of the wick 15 greatly reduced. This lamp has the
further advantage of not becoming extinguished when molined, even at an angle
of 45°, a result which as regaids miners' lamps has never heretofore been
attamed.
Finally, I would observe that my safety lamp (with its lens and its reflector) is
very little heavier than a lamp not provided with these accessories and the height
is that of the ordinary safety lamps consequently the employment of my improved
lamps will cause no change in the usual habits of a miner.
For conductors of trains or cages in miues I can provide lamps with magnifying
glasses, coloured or not, so as to signal their approach from a distance."
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. A miner's safety lamp comprising a base forming an oil reservoir, air tubes
for the oxidation of the combustible gases and for cooling the oil reservoir, a safety
lock, a cage screwed upon the oil reservoir by a collar, a lenticular glass, a
chimney of sheet metal and wire gauze held between the glass and the upper
collar of the cage and a double casing of wire gauze surmounted by a hood or cover
to which is fixed a hook for suspending the lamp substantially as herembefor
described and illustrated in Figures 1, 2, 3, 4 and 5 of the accompanying
drawings.
2. In a safety lamp such as that referred to in Claim 1 an oil reservoir
traversed by vertical an tubes covered at the lower part with wire gauze the said
reservoir being also traversed by oblique air tubes extending from the bottom of
the reservoir to the side of the casing substantially as herein before described and
illustrated in Figures 3, 4 and 5 of the accompanying drawings.
3. In a safety lamp such as that referred to in Claun 1 a safety look for
preventing access to the screw pin which prevents the opening of the lamp
substantially as hereinbefore described and illustrated in Figures 3 and 5 of the
accompanying drawings
4. In a safety lamp such as that referred to in Claim 1, a smooth or striated!
lenticular glass for magnifying the image of the flame substantially as hereinbefore
described and illustrated in Figures 3 and 9 of the accompanying diawings.
5. In a safety lamp such as that referred to in Claim 1 a reflector of polished
metal in combination with a biconvex lens substantially as hereinbetono described
and illustrated in Figmes 12, 13 and 14 of the accompanying drawings.
6. In a safety lamp of the kind referred to in Claim 1, a conical chimney
provided with a collar of double wire gauze and covered with a casing of wire
gauze the truncated conical base of which is covered with a casing of sheet metal
provided with holes substantially as herein before described and illustrated in
Figures 3, 6 and 7 of the accompanying drawings
7 In a safety lamp such as that referred to in Claim 1 an external casing for the
chimney formed of two thicknesses of wire gauze substantially as described and
illustrated in Figures 3 and 8 of the accompanying drawings.
8. An improved miner's safety lamp comprising a cylindrical oil reservoir
having air tube and safety plate, a cage screwed upon the oil reservoir with au
upper collar adapted to hold between itself and the cylindrical glass the chimney
and the outer casing which sui rounds it substantially as hereinbofore described and
illustrated in Figures 17, 18 19 and 20 of the accompanying drawings.
9. In a safety lamp such as that referred to in Claim 8, an oil reservoir traversed
obliquely by air tubes for feeding the flame, such tubes opening into a bent tube
fixed beneath the oil reservoir and having its two ends open and filled with.

page_text: metal shavings or provided with wire gauze coverings to prevent the entrance of
fire damp substantially as herembefore described and illustrated in Figures 18 and 19
of the accompanying drawings.
10. In a safety lamp such as that referred to in Claim 8, a hinged plate which is
fixed by solder to the oil reservon casing to prevent access to the screw pin which
prevents the opening of the lamp or the unscrewing of the cage substantially ns
bereinbefore described and illustiated in Figures 16, 18 and 19 of the accompanying
drawings.
11. In a safety lamp such as that referred to in Clann 8, a chimney c³ of wire
gauze enclosed in a metallic casing d' closed at the top and formed double to a
certain height from its base, substantially as herembefore described.
a sheet
12. In a safety lamp such as that referred to in Claim 8, a wire gauze casing
closed at the top covering the chimney and being itself enclosed in
metal casing e² having two series of holes arranged substantially as hereinbefore
described.
13. The manufacture and use of the improved safety lamps for minors
substantially as herein before described and illustrated in the accompanying
drawings.
Dated the 28th dor of October 1805
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.