IMPROVEMENTS IN THE CONSTRUCTION OF SAFETY OR DAVY LAMPS
Year: 1860

page_text: LETTERS PATENT to James Wright, of 42, Bridge Street, Blackfriars,
City of London, Civil Engineer, for the Invention of "IMPROVEMENTS IN
THE CONSTRUCTION OF SAFETY OR DAVY LAMPS."-A communication from
abroad by Mr. Laurent Lermusiaux, of Paris, in the Empire of France.
PROVISIONAL SPECIFICATION left by the said James Wright at
the Office of the Commissioners of Patents, with his Petition, on the
13th September 1860.
I, JAMES WRIGHT, of 42, Bridge Street, Blackfriars, City of London, Civil
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE CONSTRUCTION OF SAPETY OR DAVY LAMPS," a communication to me
from abroad by Mr. Laurent Lermusiaux, of Paris, in the Empire of France,
to be as follows:-
The object of my Invention consists in forming the lamp so as to render it
unnecessary, and to a certain extent, without special apparatus impossible to
open after it has been put into the hands of the workmen.
My lamp has the same form and possesses the usual wire gause chimney,
and top as the ordinary Davy, but in order to extinguish, or to diminish, or
increase the light, by elevating or depressing the wick without taking off the
chimney, I adopt the following plan:-On the top of the oil reservoir is

page_text: placed the wick bearer, which I form with the usual serrated wheel, which
when turned raises or lowers the wick. The mill-headed button upon the end
of this rack is formed with teeth which gear into a pinion attached to the
inside of the chimney, so that when the latter is turned to the right or left the
pinion acting upon the rack raises or lowers the wick.
The next part of my Invention relates to the mode of fixing the chimney and
cover to the oil reservoir, so as to prevent their removal without special appa-
ratus. The part underneath the oil reservoir I form into two compartments
by means of a central diaphram of steel or other like substance, such that
when formed in two equal portions having the sides hinged or turning on
centres, the interior edges will be perfectly air-tight when both flaps come into
the same plane. In the upper compartment formed by this bivalve diaphram
and the bottom of the oil reservoir is a small lever, which is actuated by the
opening and shutting of the said diaphram. The bottom compartment is formed
by this said diaphram and the real bottom of the lamp, which latter has its
-central part perforated with small holes; passing through a tube from top to
bottom of the oil reservoir is a small pin encircled by a spiral spring, which
when compressed forces the pin upwards; the bottom of the pin is connected
with the lever in the lower compartment before mentioned. In the under
surface of the cover is one or more recesses or indents of a diameter to fit the
head of the said pin. The cover now being put on is turned round until the
pin comes over the recess in its under surface into which the spring forces it,
and hence renders it impossible to turn it back and remove the cover without
depressing the spring, which cannot be got at by the workman. When, how-
ever, it is required to be opened to refill with oil or other purposes, the
following is the mode:-The two flaps of the diaphram are in the ordinary
state open, and hence the lever which is acted upon by them, and in turn acts
upon the pin, is raised up; if the valves can be brought together the lever will be
depressed, and this depression will draw the pin out of the recess in the cover,
and allow the latter to be removed. To do this I simply apply an exhauster
to the perforated bottom, so as to withdraw the atmosphere, when the pressure
from above closes the flaps, and thus brings down the lever and pin. By
altering the position of the lever and flaps it will be seen that instead of using
an exhaust, an upward pressure by the action of steam or other means might
be used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said James Wright in the Great Seal Patent Office on the
13th March 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
WRIGHT, of 42, Bridge Street, Blackfriars, City of London, Civil Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of September, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-third year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said James Wright, Her special licence that I, the said James Wright, my
executors, administrators, and assigns, or such others as I, the said James
Wright, my 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 "IMPROVEMENTS IN
THE CONSTRUCTION OF SAFETY OR DAVY LAMPS," a communication to him from
abroad by Mr. Laurent Lermusiaux, of Paris, in the Empire of France, upon
the condition (amongst others) that I, the said James Wright, my executors or
administrators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of the said
Invention, 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 I, the said James Wright, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, that is to say:-
My Invention consists in forming the lamp so as to render it unnecessary, and
to a certain extent, without special apparatus, impossible to open after it has
been put into the hands of the workmen.
My lamp has the same form and possesses the usual wire-gauze chimney
and top as the ordinary Davy, but in order to extinguish or to diminish, or
increase the light by elevating or depressing the wick without taking off the
chimney, I adopt the following plan:-On the top of the oil reservoir is placed
the wick bearer, which I form with the usual serrated wheel, which when
turned raises or lowers the wick. The mill-headed button. upon the end of

page_text: this rack is formed with teeth which gear into a pinion attached to the inside
of the chimney, so that when the latter is turned to the right or left the pinion
acting upon the rack raises or lowers the wick.
The next part of my Invention relates to the mode of fixing the chimney
and cover to the oil reservoir, so as to prevent their removal without special appa-
ratus. The part underneath the oil reservoir I form into two compartments
by means of a central diaphragm of steel or other light substance, such that
when formed into two equal portions, having the sides hinged or turning on
centres, the interior edges will be perfectly air-tight when both flaps come into
the same plane. In the upper compartment formed by this bivalve diaphragm
and the bottom of the oil reservoir, is a small lever which is actuated by the
opening and the shutting of the diaphragm, the bottom compartment formed
by this said diaphragm, and the real bottom of the lamp, which has its central
part perforated with small holes. Passing through a tube from top to bottom
of the oil reservoir is a small pin encircled by a spiral spring, which when com-
pressed forces the pin upwards; the bottom of the pin is connected with the
lever compartment before mentioned. In the under surface of the cover is one
or more recesses or indents of a diameter to fit the head of the said pin. The
cover now being put on is turned round until the pin comes over the recess in
its under surface into which the spring forces it, and hence renders it impos-
sible to turn it back and remove the cover without depressing the spring,
which cannot be got at by the workman. When, however, it is required to
be opened to refill with oil, or for other purposes, the following is the mode :―
The two flaps of the diaphragm are in the ordinary state open, and hence the
lever which is acted upon by them, and in turn acts upon the pin, is raised
up; if the valves can be brought together the lever will be depressed, and this
depression will draw the pin out of the recess in the cover, and allow the latter
to be removed. To do this I simply apply an exhauster to the perforated
bottom, so as to withdraw the atmosphere, when the pressure from above closes
the flaps, and thus brings down the lever and pin. By altering the position of
the lever and flaps it will be seen that instead of using an exhaust an upward
pressure by the action of steam or other means might be used.
In order more clearly to shew the nature of my Invention I have to this
Specification appended the accompanying Drawings, which are intended to
illustrate the forms and mode of combining the various parts of the lamp.
Figure 1 represents a vertical section passing through the axis of the lamp.
Figure 2 is an elevation of the lamp. Figure 3 an horizontal section on the
C, D. Figure 4 a view of the underneath of the chimney, with the serrated
wheel 9, which raises cr lowers the wick. Figure 5 is a plan of the lamp

page_text: without the chimney. Figures 6 and 7 represent in plan and elevation the
lower disk of the lid, having four fastenings or teeth.
Secondly, of a
It will be seen that the lamp is necessarily composed of two main parts,
firstly, of an oil reservoir a, closed at the top by a disk b, to which is fixed the
wick-bearer c, and at the base are the two bottoms d and e, between which the
mechanism necessary for the opening of the lamp is placed.
wire gauze chimney F affixed to a toothed rim round the bottom, and fastened
to the lid h (Figs. 1, 6, and 7) which bears the rods or supports i surrounding
the chimney; these are held together at the top by the disk J. This lid once.
fastened none of the interior portions of the lamp can be touched by the work-
men. The lid is secured by means of the projections or teeth L belonging to
the disk h, which fit into the notches m, m, on the collar or rim y (Figs. 1
and 5). This disk bears a small socket n, into which passes the extremity of
the pin o, o, passing through the oil reservoir by means of the tube p fixed to.
the bottoms c and d, and is forced upwards by the spiral spring 9 pressing
against the cover r. The pin once bolted into the socket n it is impossible to
open the lamp without withdrawing this pin, which is now enclosed within
the interior of the lamp. To effect this I attach a piece s perforated with
holes 1, 2, 3, 4, &c. to the bottom e; between the two bottoms d and e I place
a thin partition or diaphragm t, t¹, made of steel or other substance perfectly
air-tight but flexible, capable of giving way under a certain pressure. The
mechanism which works the pin o, o¹, is composed of a forked lever u (Figs. 1
and 3) fastened to the flexible partition t, t', by the strap V, and to the bottom
d by the hinge x, and the fork of the lever encompasses the lower part o¹ of
the pin.
If then I apply the piece s belonging to the base of my lamp to an
exhauster so as to cause a vacuum underneath the partition t, the pressure of
the air will cause the partition as well as lever u and the pin or bolt o, o²,
to take the position indicated by the red lines, which will disengage the pin or
bolt o from the socket n, and allow the lamp to be opened.
By another arrangement of the lever u the motion of the pin or bolt may be
effected by applying a pressure against the partition t, t, either by means of
steam or otherwise. The gearing wheel g attached to the chimney F, catching
into the pinions K and K' acts upon the wick so as to make it rise or lower.
when the chimney F is turned round.
In order to apply my arrangement to those lamps which have the wicks
trimmed with hooks as in the ordinary Davy lamps, I adopt the following, that
is, I suppress the flexible partition t, t, and the lever u, and concentrate the
action of the pneumatic action in the tube p which encloses the pin o, o', which,

page_text: fastens the lamp. This arrangement is indicated in Fig. 8, which is a vertical
section of the oil reservoir of the Davy lamp. The oil reservoir A has a tube
passing through it. In the interior of this tube is placed the other tube D,
which encloses the coiled spring which pushes the pin (see Figs. 9 and 10), and
to which is fixed the cover F, serving as guide to the pin, and also at the top the
cover G, which is slightly convex, and on which is a small piece of caoutchouc
packing H, attached on the one end to the pin E, and on the other to the
tube C at the point I, so as to intercept at the top of the tube C all passage to
the air, and to produce a hollow piston. The lower part of the tube C is closed
by the bottom N, which is perforated with one hole; above this bottom the
partition K is fixed to the tube C; this partition is perforated with one or
several holes for the passage of air; it serves to fasten the coiled spring D at
its base; L is the wick bearer, and M the rod of the snuffer passing through
the reservoir of the lamp in. a narrow tube.
The following is the way in which the opening or shutting of the lamp is
produced by the action of the vacuum:-The bottom of the tube C is placed
underneath the bottom P at the place indicated by J on the air-pump, which
when actuated produces the vacuum in tube C, and consequently the hollow
piston G, H, I, is drawn into the interior of the tube, and causes the disk H,
which is made of caoutchouc, to descend into the tube until the pin E is with-
drawn from the socket n adjoining to the cover F, which is regulated by the
distance which exists between the end of the pin E and the cover K. The
Figures 8 and 9 shew the position of the pin when the lamp is shut, and
Figure 10 represents it, the lamp being open, that is to say, at the time the
vacuum has been obtained in the interior of the tube C.
By this new arrangement the repairs are made very cheaply. If a new
spring is required it will suffice to unsolder the bottom N and the cover K.
Instead of placing separately the four teeth L, L, L, L, I obtain them by
prolonging the rods i, i, as indicated in Figure 11.
Having now described the nature of my Invention, and how the same is
constructed and acts, I wish it understood that what I claim as new and
desire secured by the before in part recited Letters Patent is,―
First, the use of a flexible disk t, and the arrangement of the lever u
acting on the pin o, o¹, by causing a pressure against this disk either by means
of steam or air.
Second, the use of pneumatic means of pressure to move a flexible partition,
either metallic or of caoutchouc, as in Figs. 1, 8, 9, and 10.
Third, the use of the chimney to act on the wick without the lamp being
opened, and also the use of a flat or round wick.

page_text: Fourth, the particular mode of fastening the lid by means of teeth, as shewn
in Figs. 1, 5, 6, 7, 8, and 11.
Fifth, the particular arrangement of my pneumatic fastening as specially
applied to Davy lamps of the kind shewn in Figs. 8, 9, and 10.
Sixth, I claim the use of my system of lamp, with pneumatic fastening, for
fabrics, of alcohol, gas, and other flame-producing products in which lamps of
this kind may be employed.
In witness whereof, I, the said James Wright, have hereunto set my
hand and seal, this Thirteenth day of March, in the year of our
Lord One thousand eight hundred and sixty-one.
JAMES WRIGHT. (L.S.)