AN ⚫ IMPROVED CONSTRUCTION OF SAFETY LAMP
Year: 1859

page_text: LETTERS PATENT to Richard Stead Howden and Edwin Thresh, both of
Wakefield, in the County of York, Engineers, for the Invention of "AN
⚫ IMPROVED CONSTRUCTION OF SAFETY LAMP."
Sealed the 23rd March 1860, and dated the 20th December 1859.
PROVISIONAL SPECIFICATION left by the said Richard Stead Howden
and Edwin Thresh at the Office of the Commissioners of Patents, with:
their Petition, on the 20th December 1859.
We, RICHARD STEAD HOWDEN and EDWIN THRESп, both of Wakefield, in
the County of York, Engineers, do hereby declare the nature of the said
Invention for "AN IMPROVED CONSTRUCTION OF SAFETY LAMP," to be as
follows:-
This Invention relates to a novel construction of lamp for the use of miners,
the object being to render the Davy or safety lamp less liable than heretofore
in careless hands to ignite the firedamp in coal mines. To this end we pro-
vide below the oil chamber a receiver for the air which is to support combus-
tion, giving the air access thereto by rings of holes at or near the foot of the
lamp. In the receiver we place wire gauze diaphragms, which divide it hori.
zontally into compartments, and through these the air must pass before it
reaches the central opening in the oil chamber, around the upper edge of
which the burner is situated. The upper part of the lamp is closed in as
usual by wire gauze cylinders which surround the flame, and the perforated

page_text: top through which the gases of combustion are given off is connected to the
lower part of the lamp by supporting rods bolted thereto. Access is gained
to the burner by detaching the upper part of the lamp from the lower in the
usual manner.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Richard Stead Howden and Edwin Thresh in the Great
Seal Patent Office on the 20th June 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, wc, RICHARD
STEAD HOWDEN and EDWIN THRESП, both of Wakefield, in the County of
York, Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of December, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
us, the said Richard Stead Howden and Edwin Thresh, Her special license
that we, the said Richard Stead Howden and Edwin Thresh, our executors,
administrators, and assigns, or such others as we, the said Richard Stead
Howden and Edwin Thresh, our executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for " AN
IMPROVED CONSTRUCTION OF SAFETY LAMP," upon the condition (amongst others)
that we, the said Richard Stead Howden and Edwin Thresh, by an instrument
in writing under our hands and seals, or under the hand and seal of one of
us, should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said Richard Stead Howden and Edwin
Thresh, do hereby declare the nature of our said Invention, and in what
manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement, reference being had to the Drawing
hereunto annexed, and to the letters and figures marked thereon (that is to
say):-
:-
This Invention relates to a novel construction of lamp for the use of

page_text: miners, the object being to increase the efficiency of the Davy or safty lamp,
and render it less liable than heretoforo in careless hands to ignite the fire-
damp in coal mines.
In the accompanying Drawing our improved lamp is shewn in sido eleva-
-tion at Fig. 1, and in vertical section at Fig. 2. Instead of the ordinary solid
wick we use a tubular wick, making an air supply through the oil chamber
or reservoir as in the ordinary Argand lamp. Below the central opening in
the oil chamber we place wire gauze diaphragms set at a short distance apart
for the purpose of cutting off the communication between the interior of the
lamp and the outer atmosphere. In other respects the lamp is very similar to
those generally in use.
a, a, is the oil chamber, the sides of which are continued downwards to
form the foot of the lamp. A ring of holes b, b, b, is made around the foot of
the lamp to ensure access of air to the interior; c is an open tube extending
upwards through the oil chamber to near the level of the wick. Concentric
with this tube is a wick-holder d, which is raised and lowered as desired by
an adjusting screw e, which is supported by a shoulder fitting into the top of
the oil chamber. The middle part of the top of this chamber is recessed, and
the edge of the recess has a screw cut upon it to enable it to receive a screwed
collar f, which carries the upper part or cover of the lamp that surrounds and
encloses the flame. This cover is composed as usual of a wire gauze cylinder g
with strengthening rods, and a cap h, to which the suspending ring is attached.
Between the collar f and the top of the oil chamber the nozzle i is secured,
which with the tube c forms an annular space for the wick to pass up. The
wire gauze diaphragms are shewn at k, k, situate immediately below the oil
chamber, and divided from each other by a loose metal collar. These dia-
phragms are held securely in place by means of a threaded ring 1 which screws
into a thread cut on the inner face of the foot of the lamp. Access is gained
to the wick and oil chamber by detaching the upper part of the lamp from
the lower in the usual manner.
It will now be understood that the air to supply combustion will when the
lamp is standing on the ground enter the holes 6 at the foot of the lamp, pass
through the diaphragms, and up the central tube e to the flame. An ample
supply of air will thus be ensured to the flame sufficient to keep up a large
bright light, while at the same time the possibility of the flame igniting fire-
damp outside the lamp is effectually avoided.
Having now set forth the nature of our Invention of an improved construc-
tion of safety lamp, and explained the manner of carrying the same into effect,
we wish it to be understood that under the above in part recited Letters

page_text: Patent, we claim the means above described for ensuring with safety a copious
supply of air to the flame of miners' lamps..
In witness whereof, we, the said Richard Stead Howden and Edwin
Thresh, have hereunto set our hands and seals, the Eighteenth day
of June, in the year of our Lord One thousand eight hundred and
sixty.
RICHARD STEAD HOWDEN. (L.S.)
EDWIN THRESH.
(L.B.)