IMPROVEMENTS IN MINERS' SAFETY LAMPS, PART OF WHICH IMPROVEMENTS IS APPLICABLE TO OTHER LAMPS OR LANTERNS "
Year: 1877

page_text: LETTERS PATENT to John Davenport Shakespear, of Ramsgate, Kent, Justice
of the Peace, for the Invention of "IMPROVEMENTS IN MINERS' SAFETY LAMPS,
PART OF WHICH IMPROVEMENTS IS APPLICABLE TO OTHER LAMPS OR LANTERNS "
PROVISIONAL SPECIFICATION left by the said John Davenport Shakespear
at the Office of the Commissioners of Patents on the 27th January 1877
JOHN DAVENPORT SHAKESPEAR, of Ramsgate, Kent, Justice of the Peace "IM-
PROVIMENTS IN MINERS' SAFETY LAMPS, PART OF WHICH IMPROVEMENTS IS
APPLICABLE TO OTHER LAMPS OR LANTERNS "
The object of the present Invention is to improve and perfect the system of
ventilation in miners" lamps mole particularly, but part of the said improvements
is also applicable as an improved means of ventilation to other lamps or lanterns
Hitherto the principal difficulty in the construction of miners' lamps has been
that of supplying a sufficient curient of an to obtain the maximum of light, and at
the same time secure the safety of the miner from the danger of explosion
In the Specification of Letters Patent granted to me for "Improvements in
Miners' Safety Lamps," and bearing date the 10th day of April, 1876, No 1510,
the ventilation of the lamp is obtained by means of a metallic ring arranged below
the wick holder and forming the basis of the combustion chamber This metal ing
is pierced with lateral holes, these being covered with wie gauze as the protection
against the firing of dangerous gases The improved lamp is also provided with a
corresponding metal ring, but the apertures therein are not piciced simply in a
radial duection but diagonally through the ring, so that the current of an as it is
drawn by the combustion of the oil does not impinge directly upon the flame
but passes into the combustion chamber in a diagonal direction, and so forms a kind
of vortex or circular current around the flame This arrangement not only increases
the intensity of the light but also maintains the steadiness of the flame This pre-
vention of flickering or waving of the flame is a most important point in miners'
lamps, and in this improved lamp it is further provided for by means of a small
metallic cylinder fitted outside and at the lower part of the ordinary wite gauze

page_text: chimney of the lamp This addition effectually prevents any flickering of the flame'
however strong the current of air may be to which the lamp is exposed
In my former Letters Patent I described the surrounding glass or combustion
chamber to be of a truncated conical figure, convex upon its internal surface, but in
the present invention I prefer to make the lenticular glass with the convex surface
outside and the plane sui face inside Or, if preferred, instead of the conical form
of glass it may be made of a cylindro-convex form
With these several improvements the flame is rendered perfectly steady, and the
maximum of illuminating power is attained
These improvements in ventilating miners' lamps lamps are also applicable to
other lamps or lanterns where it is desirable to shield-the-flame from direct currents
of air which this diagonal system of regulating the au effectually secures
SPECIFICATION in puisuance of the conditions of the Letters Patent filed
by the said John Davenport Shakespear in the Great Seal Patent Office on
the 27th July 1877
"IM-
JOHN DAVENPORT SHAKESPEAR, of Ramsgate, Kont, Justice of the Peace
PROVEMENTS IN MINERS' SAFETY LAMPS, PART OF WHICH IMPROVEMENTS IS
APPLICABLE TO OTHER LAMPS OR LANTERNS "
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
Diawings and to the letters and figuies marked thereon, that is to say,-
Figure 1 is an elevation of the principal portion of a miner's lamp shewing my
improvements applied thereto, Figure 2 is a vertical section of the same
Figure 3 is a plan and elevation of the ventilating ng shewing the diagonal and
other apertures which carry the currents of an into the combustion chamber and
thus maintain a steady and uniformly brilliant flame from the wick of the lamp
The lamp A is of the usual kind as applied to miners' lamps, and it is screwed
into the ing piece B, within which is secured the ventilating ring C which surrounds
the combustion chamber E The ring C is pierced with any convenient number of
holes D These apertures are carried through the ing in a diagonal duection, as
indicated by the dotted lines, and they are by preference about the 32nd part of an
inch in diameter, more or less, but they are sufficiently small to prevent the passage
therethrough of any flame that would endanger the safety of the pit
In those pits where from the system of ventilation the currents of air and gases
are caused to move at a high velocity I prefer to surround the diagonally perforated
ling with a secondary guard F This guard is formed of a thin ring of metal and
cap piece which surrounds and encloses the ing C The face of the ring is per-
foiated with fine apertures, or, if preferied, this part may be formed of wire gauze
With this addition I have found that the flame of the lamp remains perfectly steady
in the strongest curients of air The lower edge of the coinbustion chamber iests in
a groove formed in the 11ng C, and the upper part fits into a groove formed on the
under side of the annular cap G, which supports the usual wire gauze chimney H.
This part of the lamp with its vertical wire guards, &c, does not differ from the
corresponding paits in lamps of the ordinary kind
I prefer to form the combustion chamber E of a conical figure, as shown, and
having its external surface of a convex figure, and so forming a circular bull's-eye
lens, which I have found to be the most efficient arrangement for diffusing the
largest amount of light. If pieferied however this part of the lamp may be made
of uniform thickness throughout
The lower part of the gauze chimney II I enclose with a thin metal cylinder I,
which moves loosely on the surface of the gauze, and serves efficiently to protect the
flame below from any impinging currents of cold air entering from above.

page_text: It will be obvious that these improvements may be applied with advantage in a
more or less modified form to other classes of lamps that are required to be used in
the open air
Having now described and particularly ascertained the nature of my said Inven-
tion, and in what manner the same is or may be carried into practical effect, I wish
it to be understood that what I consider to be novel and useful, and therefore claim
under the herein-before in part recited Letters Patent is,-
First. The arrangement and construction of miners' safety lamps in which the
due and effective ventilation of the lamp is obtained by means of a metal ing
perforated with apertures extending through the ring in a direction diagonal to its
periphery, and further surrounded or not by a secondary perforated ung, or with
wire gauze, substantially as herein-before described and shown in the accompanying
Drawing, or any meie modification thereof
Secondly The forming of the conical combustion chamber with an external
convex surface, or, if preferred, of uniform thickness throughout. Also the metal
guard at the base of the wire gauze chimney, as herein-before described and shown
in the accompanying Drawing
In witness whereof, I, the said John Davenport Shakespear, have herounto set
my hand and seal, this Twenty-seventh day of July, in the year of our Lord
One thousand eight hundred and seventy-seven.
Witness,
CHARLES BARLOW,
Patent Agent,
23, Southampton Buildings,
London, WC.
10
J. D. SHAKESPEAR. (Ls.)