IMPROVEMENTS IN MINERS' SAFETY LAMPS
Year: 1876

page_text: LETTERS PATENT to John Davenport Shakespear, of Ramsgate, in the County
of Kent, Justice of the Peace, for the Invention of "IMPROVEMENTS IN MINERS'
SAFETY LAMPS."
ealed the 7th October 1876, and dated the 10th April 1876.
PROVISIONAL SPECIFICATION left by the said John Davenport Shakespear
at the Office of the Commissioners of Patents.on the 10th April 1876.
JOHN DAVENPORT SHAKESPEAR, of Ramsgate, in the County of Kent, Justice of
the Peace. "IMPROVEMENTS IN MINERS' SAFETY LAMPS."
My improved lamps consist of the same general parts as the ordinary lamps, but
I have introduced different material and form. The oil box has a porcelain or
stoneware top, or may be constructed entirely of porcelain or stoneware, the object
being to keep the oil box cool by intercepting between the oil in the box and the
wick holder a substance of low conducting power. I use a combustion chamber
after the fashion of the Clanny lamp, but with the difference that mine is conical
instead of cylindrical, and it may be made of glass or of talc, or mica, or of wire
gauze; also I ventilate this combustion chamber by wire gauze or by small holes:
One of the advantages of the conical form of the combustion chamber is that the
flame can easily come in contact with the sides when the lamp is held out of the
perpendicular. Above the combustion chamber is a wire gauze chimney of the
usual kind but without the usual gauze cap close fitting at the sides; in lieu of
this latter I substitute a gauze cap of conical form, having for its object a space
between the gauze of the chimney and the gauze of the cap, thus preventing the
possibility of the sides of the outer gauze over heating by contact. Instead of solid
upright pillars or supports for giving rigidity to the lamp, I use hollow tubes open
at both ends for coolness. Instead of the ordinary round wick I use a flat wick,
and to the wick holder I attach a small tube to convey air to the oil below, that
capillary attraction may not be too much impeded by the close fittings of the box.
I use a reflector or reflectors for the double purpose of reflecting and of giving to
the flame a support or protection in a strong current of air. I use a compound of
animal, vegetable, or mineral oils, and with or without any chemicals, having for its.
[Price 6d.]

page_text: object clearness of light and reduction of smell. Instead of trimming the lamp by
a tube or wire through the oil box, I do this by means of an apparatus through
the side of the lamp.
SPECIFICATION in pursuance of the conditions. of the Letters Patent filed by
the said John Davenport Shakespear in the Great Seal Patent Office on the
10th October 1876.
JOHN DAVENPORT SHAKESPEAR, of Ramsgate in the County of Kent, Justice of
the Peace. "IMPROVEMENTS IN MINERS' SAFETY LAMPS."
The object of this Invention is to increase the utility of the miners' safety lamp,
so that it may afford a much larger amount of light with a steadily burning flame,
points of the utmost importance to the miner.
And in order that my said Invention of "Improvements in Miners' Safety Lamps"
may be properly understood and carried into practical effect, I will now proceed to
describe the same more particularly, reference being had to the accompanying Sheet
of explanatory Drawings, and to the letters and figures marked thereon; that is
to say-
Figure 1 on the accompanying Drawing is an elevation of my improved miner's
safety lamp.
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Figure 2 is a vertical section of a portion of the lamp, to shew more particularly
the construction of the improved combustion chamber; and
Figure 3 is a vertical. section of another mode or modification of the system of
ventilating the lamp or conveying air to the combustion chamber.
The lamp A is of the usual form, and screws into the ring B, and it is securely
locked therein by the screw C, which passes through the laterally projecting lug D.
The head of the screw enters a recess in the lug, so that the screw cannot be easily
unfastened by the miner without a suitá le instrument. At the upper part of the
ring piece B a ring of wire gauze E is fitted in a brass collar, having a central
opening immediately below the combustion chamber. The wire gauze E is in close
contact with the annular ventilator F. This consists of a perforated ring of metal
extending from the outer ring G to the brass fillet H, which receives the lower rim
of the combustion chamber I. The external air for the supply of oxygen to the
lamp flame passes freely through the apertures in the ventilator F and the gauze E,
which serves as a protector to prevent the ignition of any dangerous or explosive
gas. In this way an excellent supply of air is furnished to the flame of the lamp,
which serves to bring out the full illuminating power of the oil, at the same time
all danger is carefully guarded against. The course of the currents of air is indicated
by the arrows, and, with the view of increasing the velocity of the ascending current
a diaphragm J is fitted inside the fillet H, and just below the lower rim of the com-
bustion chamber 1. The diaphragm J is simply a disc of brass with a central
aperture opening into the combustion chamber, but which partially contracts the
opening and thus increases the velocity of the ascending current of air. The com-
bustion chamber I is, by preference, made in the form of an inverted frustum of a
cone, as shewn in the Drawing, where it is seen in external elevation in Figure 1
and in vertical section in Figure 2. It may be made either of ordinary glass of
good quality or of that variety of carefully annealed material which is known as
toughened glass." The external face of the chamber presents that of an inverted
truncated cone, but the inner surface is of a curved lenticular figure, as shewn more
particularly in Figure 2. The effect of this particular form or mode of construction
is to largely increase the illuminating power of the lamp, since from the peculiar
form of the inner surface of the chamber it virtually forms an annular lens, and as
such it diffuses a much more, concentrated light than would be the case with an
ordinary cylinder. The increase of light, thus obtained will, it is obvious, enable

page_text: the miner to work with greater facility and comfort in this respect than heretofore,
a most important desideratum in this branch of industry. The upper rim of the
glass chamber I is fitted in the annular cap K, and abuts against an upper dia-
phragm L, which forms a portion of the cap piece. This diaphragm, like the lower
one J, serves to contract the air passage, and the joint action of the two causes the
flame to burn steadily and without flickering from unsteady draught or excess of
air. The chamber I is protected externally by the vertical guards M, as usual in
lamps of this class. There is also the usual wick trimmer N, which is operated in
the ordinary manner from the bottom of the lamp, as indicated by the dotted lines
in Figure 1.
The upper portion of the lamp does not differ in any material respect from those
in ordinary use, and, therefore, need only be briefly referred to.
The wire gauze
chimney O is of the usual kind, and is protected by the vertical guards P, which
are carried into the upper ring Q. Above this ring is the cap R, which is hinged
on one side and secured by a padlock on the eye S on the other side. The handle T,
by which the lamp is carried or hung at any desired spot, completes the details of
the several parts.
Figure 3 is a vertical elevation of a portion of a safety lamp corresponding to the
portion B of the lamp shewn in Figures 1 and 2. In this modification the ring B
is in all respects similar to that before described. This ring is perforated laterally,
as shewn by the horizontal line of apertures F"; externally the ring is turned down
to a diameter somewhat smaller than the lower part, and in the recess thus formed
an outer protective covering of wire gauze E is fitted neatly and tightly over the
lateral openings. In this way the air passes first through the outer ring of gauze E
and then through the apertures F made in the ring B; or in other words, the air
enters directly in a lateral direction in contradistinction to the descending currents,
as shewn in the arrangement delineated in Figure 2, at the same time it is perfectly
safe.
In the ordinary "Clanny” lamp, the Invention of Dr. W. R. Clanny, of Sunder-
land, the combustion chamber is of a simple cylindrical form, and does not in any
way assist in diffusing or concentrating the rays of light any more than would a
plain cylinder applied to a lighthouse, where it would be practically useless as com-
pared with the lenticular arrangement now generally adopted. So also with the
improved lamp herein-before described, and which will be hereafter known as the
"Shakespear" lamp, the lenticular form of the glass of the combustion chamber
imparts to it the utility and advantages of the plano-convex lens known as the
"bull's eye," but with this important advantage, that here the lens entirely
surrounds the flame, and hence there' is nothing whatever to impede the diffusion
of the rays of light in every direction around the lamp. On the other hand, the
maximum amount of illuminating power as well as steadiness of the flame is
obtained by the arrangement of the ventilator and the duplex diaphragms, as shewn
and described.
Having now described and ascertained the nature of my said Invention of
improvements in miners' safety lamps, and in what manner the same is or may be
carried into practical effect, I desire it to be understood that I do not confine
myself to the precise mechanical arrangement of the details I have herein-before
described and shown in the accompanying Drawing so long as the essential and
distinctive features of the improvements are adhered to; but what I do claim and
desire to secure by the herein-before in part recited Letters Patent is-
First. The constructing of the combustion chambers of miners' safety lamps in
the form of a truncated cone inverted and with one of its surfaces formed of a
parabolic or lenticular figure, for the purpose of increasing the utility of the lamp,
as herein-before described and shewn in the accompanying Drawing, or any inere
modification thereof.
Second. The arrangement and construction of the perforated ventilator and wire
gauze protecting ring beneath, as well as the lower and upper diaphragms, for the

page_text: purposes of utility and with the objects herein-before described and shewn in the
accompanying Drawing, or any mere modification thereof.
In witness whereof, Į, the said John Davenport Shakespear, have hereunto
set my hand and seal, this Tenth day of October, in the year of our Lord
One thousand eight hundred and seventy-six.
Witness,
CHARLES BARLOW,
23, Southampton Buildings, W.C.,
Patent Agent.
J. D. SHAKESPEAR. (L.S.)