IMPROVEMENTS IN LAMP CASINGS OR HOLDERS FOR CONTAINING AND PROTECTING ELECTRIC LIGHTS, AND IN APPARATUS TO BE USED IN CONNECTION THEREWITH, THE SAID APPARATUS BEING IN PART APPLICABLE FOR OTHER PURPOSES."
Year: 1881

page_text: LETTERS PATENT to David Graham, the younger, of Glasgow, in the County
of Lanark, North Britain, for an Invention of " IMPROVEMENTS IN LAMP
CASINGS OR HOLDERS FOR CONTAINING AND PROTECTING ELECTRIC LIGHTS,
AND IN APPARATUS TO BE USED IN CONNECTION THEREWITH, THE SAID
APPARATUS BEING IN PART APPLICABLE FOR OTHER PURPOSES."
PROVISIONAL SPECIFICATION left by the said David Graham at the Office
of the Commissioners of Patents on the 26th July 1881.
"
DAVID GRAHAM, the younger, of Glasgow, in the County of Lanark, North
Britain. IMPROVEMENTS IN LAMP CASINGS OR HOLDERS FOR CONTAINING AND
PROTECTING ELECTRIC LIGHTS, AND IN APPARATUS TO BE USED IN CONNECTION
THEREWITH, THE SAID APPARATUS BEING IN PART APPLICABLE FOR OTHER
PURPOSES."
"
The first part of this Invention relates to an improved casing or lanthorn for
containing and protecting electric lights, either the incandescent, partly incan-
descent, or are lights. The lanthorn or casing when constructed for incandescent
lights consists of an upper part, into which the conductors from a battery or an
electro-dynamic machine are led. This upper part is hollow in the inside, and so
arranged as to receive the stem and contact pieces of a "Swan or equivalent
electric lamp. This upper part is connected by one or more bayonet or equivalent
joints to the lower part or lanthorn proper, and the two parts are locked together
by means of a padlock, which consists of an upper and lower metallic portion
connected together by wires or bars of metal bent or shaped according to the
contour of the glass portion of the lantborn, this glass portion being preferably
cushioned elastically within the metallic portion, and adjusted together with the
protecting wires or bars by a nut and screw or equivalent arrangement at the lower
part. The upper and lower parts of the lamp casing or lanthorn are provided
with swivel rings for suspending or carrying the same.

page_text: Lamps constructed as hereinbefore described are especially adapted for miners'
lamps and for subaqueous illumination. .
In the case of lamps or lanthorns for lighting such places as warehouses, factories,
or private dwelling houses, the lamp casing or lanthorn is preferably made as a
flat or curved metallic reflector at the upper part, to which the lower part or glass
casing is attached by a bayonet or equivalent joints so made as to be by preference
practically air tight and dust tight, so that as the dust will pass but very slightly
to the interior of the lamp case or lanthorn within which the electric light is placed,
it will only be necessary to wipe the dust off the exterior of the glass case or
lanthorn in order to keep the entire lamp clean and bright. The glass casing is
made at the upper part preferably with a
to be firmly secured within the ring which carries the bayonet joints, or the upper
flange, or thickened at that part so as
or thickened part of the glass may have the said joints formed therein so as to fit
upon studs carried in the reflecting surface of the lamp casing or lanthorn. In
this case a shadowless lamp case or lanthorn is produced.
For some purposes it may be useful to make the glass casing or lanthorn of a
deep or elongated form, and with a conical reflector projecting down thereinto
with the electric light at the lower part thereof.
Another part of this Invention relates to the so constructing of electric lamps
that they are rendered portable and can be suspended at any point through which
a current passes, and so be moved from place to place without the necessity of
cable or conducting wires being attached to the said lamp. This part of my
Invention consists in placing brackets, sockets, or other means of suspension at
such points in the building or elsewhere where lighting is or may be required.
This part of the Invention may be carried out in several ways, and it consists
primarily in having the aforesaid hooks or sockets or their equivalent all connected
in circuit, and preferably with a resistance coil or its equivalent at each point
where a lamp is or may be attached. The lamps are so constructed that on putting
one of them in circuit it puts the resistance coil or its equivalent out of circuit, and
on being taken out of circuit it brings the resistance coil or its equivalent into
circuit. Or instead of this arrangement, at the place or places where a lamp
requires to be put in circuit, a stopper or plug or its equivalent may be used,
which being pressed against a spring or lever or the equivalent thereof, the
resistance coil is put out of circuit and the lamp put into circuit. Or an ordinary
switch may be used at each place where a lamp is or may be attached. It is to
be understood that these arrangements for putting the lamps into or out of circuit
may be used for series of lamps as well as for single lamps.
In the case of using the lamp cases or lanthorns, hereinbefore described, for arc
lights, or partly are and partly incandescent lights, they must be made sufficiently
large to contain the mechanism used in connection with such lights.
The second part of the Invention relates to apparatus for making and breaking
contact, so that the spark produced at the making or breaking of contact is
prevented, in the case of mines or other places where electric lights or other electric
apparatus is used, from communicating with inflammable gases or other inflammable
material.
This apparatus consists of either a single or double receptacle which contains
mercury in the lower parts thereof in communication with the electric conductors..
Into this trough or troughs there. dip metallic bars, and the upper part of the
trough or troughs is filled with water, or with water having oil floating on it.
When therefore contact is made or broken by lowering or raising the bar or bars
into or out of the mercury, the spark then produced is by means of the water kept
from igniting any inflammable gases with which the atmosphere of the place where
such apparatus is used is or may be charged.
This last named apparatus may be used in any place or places wherein the
making and breaking of contact becomes necessary.
In another form of the apparatus for making and breaking contact, the use of a
metallic bar is dispensed with, and the apparatus in such case consists of one or

page_text: more vessels, into or through which acidulated water or mercury capable of
being raised and lowered within a closed tube so as to make or break contact
is employed.
Another form of apparatus for making and breaking contact consists of a tube
pivotted at its centre so that it can be moved to an angle on either side of the
horizontal on the said pivot. This tube is fitted at each end with insulated or
separated pieces of metal, and the tube contains within it a little mercury, a
metallic ball, or metallic dust or filings, or a conducting liquid, or the equivalent
of these, which on being caused to fall to the lowest part of the tube when the
said tube is inclined makes contact, and when the tube is moved in the opposite
direction breaks that contact.
The glass tube is or may be provided with a receptacle at its lower central part,
into which the mercury or the equivalent thereof would flow and rest when the
said tube is placed horizontally or nearly so. By this arrangement both ends of the
tube are kept out of circuit. The mercury when in this recess may also make
contact with the conducting wires of the circuit, or it may be thereby connected to
a resistance coil, or to other form of resistance apparatus.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Graham in the Great Seal Patent Office, on the 26th January
1882.
DAVID GRAHAM, the younger, of Glasgow, in the County of Lanark, North
Britain. "IMPROVEMENTS IN LAMP CASINGS OR HOLDERS FOR CONTAINING AND
PROTECTING ELECTRIC LIGHTS, AND IN APPARATUS TO BE USED IN CONNECTION
THEREWITH, THE SAID APPARATUS BEING IN PART APPLICABLE FOR
PURPOSES."
OTHER
The first part of this Invention relates to an improved casing or lanthorn for
containing and protecting electric lights, either the incandescent, partly incandescent,
or arc lights. The lanthorn or casing when constructed for incandescent lights
consists of an upper part into which the conductors froin a battery or a dynamo.
machine are led. This upper part is hollow in the inside and so arranged as to
receive the stem and contact pieces of a "Swan" or equivalent electric lamp.
This upper part is connected by one or more bayonet or equivalent joints to the
lower part or lanthorn proper, and the two parts are locked together by means of a
padlock. The lanthorn proper consists of an upper and lower metallic portion
connected together by wires or bars of metal bent or shaped according to the
contour of the glass portion of the lanthorn, the glass portion being preferably
cushioned elastically within the metallic portion and adjusted together with the
protecting wires or bars by a nut and screw or equivalent arrangement at the
lower part. The upper and lower parts of the lamp casing or lanthorn are provided
with swivel rings for suspending or carrying the same.
Lamps constructed as herein before described are especially adapted for miners'
lamps and for subaqueous illumination.
In the case of lamps or lanthorns for lighting such places as warehouses,
factories, or dwelling houses, the lamp casing or lanthorn is preferably made as a
flat or curved metallic reflector at the upper part, to which the lower part or glass
casing is attached by a bayonet or equivalent joints so made as to be by preference
practically air-tight and dust-tight, so that as the dust will pass but very slightly
to the interior of the lamp case or lanthorn within which the electric light is placed,
it will only be necessary to wipe the dust off the exterior of the glass case or
lanthorn in order to keep the entire lamp clean and bright. The glass case is
made at the upper part preferably with a flange, or thickened at that part so as to
be firmly secured within the ring which carries the bayonet joints, or the upper or
thickened part of the glass may have the said joints formed therein so as to fit
upon studs carried in the reflecting surface of the lamp casing or lanthorn. In
this case a shadowless lamp case or lanthorn is produced.
For some purposes I make the glass casing or lanthorn of a deep or elongated
. form and with a conical reflector projecting down thereinto with the electric light
at the lower part thereof.
Another part of this Invention relates to the so constructing of electric lamps
that they are rendered portable and can be suspended at any point through which
a current passes, and so be moved from place to place without the necessity of
cable or conducting wires being attached to the said lamp. This part of the
Invention consists in placing brackets, sockets, or other means of suspension at
such points in the building or elsewhere where lighting is or may be required.
This part of the Invention may be carried out in several ways, and it consists
primarily in having the aforesaid hooks or sockets or their equivalents all
connected in circuit, and preferably with a resistance coil or its equivalent at each
point where a lamp is or may be attached. The lamps are so constructed that on
putting one of them in circuit it puts the resistance coil or its equivalent out of

page_text: .
circuit, and on being taken out of circuit it brings the resistance coil or its
equivalent into circuit. Or instead of this arrangement, at the place or places
where a lamp requires to be put in circuit a stopper or plug or its equivalent may
be used, which being pressed against a spring or lever, or the equivalent thereof,
the resistance coil is put out of circuit and the lamp put into circuit; or an
ordinary switch may be used at each place where a lamp is or may be attached.
It is to be understood that those arrangements for putting the lamps into or out of
circuit may be used for series of lamps as well as for single lamps.
In the case of using the lamp cases or lanthorns herein before described for arc
lights, or partly arc and partly incandescent lights, they must be made sufficiently
large to contain the mechanisin used in connection with such lights.
The second part of the Invention relates to apparatus for making and breaking
contact, so that the sparks produced at the making or breaking of contact is
prevented in the case of mines or other places where electric lights or other olectric
apparatus is used, from communicating with inflammable gases or other inflammable
material.
This apparatus consists of either a single or double receptacle which contains
mercury in the lower part thereof in communication with the electric conductors.
Into this trough or troughs there dip metallic bars, and the upper part of the
trough or troughs is filled with water or with water having oil floating on it.
When therefore contact is made or broken by lowering or raising the bar or bars
into or out of the mercury, the spark then produced is by means of the water kept
from igniting any inflammable gases with which the atmosphere of the place where
such apparatus is used is or may be charged.
This last named apparatus may be used in any place or places wherein the
making and breaking of contact becomes necessary.
In another form of the apparatus for making and breaking contact the use of a
metallic bar is dispensed with, and the apparatus in such case consists of one or
more vessels into or through which acidulated water or mercury capable of being
raised and lowered by a pump or its equivalent within a closed tube so as to make
or break contact is employed.
Another form of apparatus for making and breaking contact consists of a tube
pivoted at its centre so that it can be moved to an angle at either side of the
horizontal on the said pivot. This tube is fitted at each end with insulated or
separated pieces of metal, and the tube contains within it a little mercury or
metallic ball or balls, or metallic dust or filings, or a conducting liquid, or the
equivalent of these, which on being caused to fall to the lowest part of the tube
when the said tube is inclined makes contact, and when the tube is moved in the
opposite direction breaks that contact.
The glass tube is or may be provided with a receptacle at its lower central
part into which the mercury or the equivalent thereof would flow and rest when
the said tube is placed horizontally or nearly so; by this arrangement both ends of
the tube are kept out of circuit. The mercury when in this recess may also make
contact with the conducting wires of the circuit, or may be thereby connected to a
resistance coil or other form of resistance apparatus.
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which
the same is or may be used or practically carried into effect, reference being had
to the accompanying Drawings and to the letters and figures marked thereon, that
is to say.
Figure 1 represents in elevation a miner's electric lamp constructed according to
my said Invention, and Figure 2 is a vertical section of the same; Figure 3 is a
plan, and Figure 4 is a horizontal section upon the line 1, 2, Figure 2.
The lanthorn or casing which is illustrated in these Figures is of a form suitable
for containing incandescent lights, and consists of an upper part A of wood,
vulcanite, or other suitable material into which the conductors B from a battery or
dynamo machine are led.

page_text: The said upper part is formed with a hollowed central portion a for the reception
of the stem c of a "Swan" lamp C. The glass stem e is held within a socket c¹ of
non-conducting material c², and the said socket is secured within the portion a
of the upper part A of the casing by means of the side spring pieces which are
placed between the outer part of the socket c¹ and the inner surface of the recess a.
The insulated conducting wires B, B, are shewn encased with a tube b of india
rubber, the said tube being firmly secured within a central opening a leading to
the recessed portion a. The wires B, B, as shown in Figure 2, are led to two
segmental plates a² which are screwed to the base of the wood or vulcanite part A,
and the current is led upwards to the two plates as screwed to the top of the stem
casing or socket c¹ where contact is made with the two platinum wires c², c², for
producing the incandescent light in the vacuum chamber C are exposed.
Having now described the method I employ for holding the "Swan" lamp
within the casing A, I will now describe the construction and mode of using the
lanthorn proper for protecting the lamp. The lanthorn proper which forms the
lower part of the apparatus consists of an upper and lower metallic portion con-
nected together by wires or bars of metal D which enclose a strong glass globe E.
The upper portion, to which the upper ends of the encasing wires or bars are
secured by rivetted heads or by other suitable means, consists of a metal ring or
collar d which fits a corresponding inner ring A' which is attached to the lower
cylindrical portion of the holder A; and the two parts of the lamp are held securely
in position by bayonet joints hereinafter described. The globe E is attached to the
inner edge of the collar d through the medium of a ring of india rubber d¹, which
is also so arranged as to act between the upper edge of the glass and the under
edge of the inner ring A¹ of the holder. The lower portion of the lanthorn
proper to which the other or opposite ends of the caging wires are secured consists
of a flanged plate upon the central portion of which at d* rests the projection e
of the glass globe E; the said projection e fitting closely within a corre-
sponding recess, at the bottom of which a cushion e₁ of india rubber is laid.
In order to adjust the globe E and to firmly secure it, I provide the plate d
with a screw d³, and I preferably secure the ends of the bars D by nuts, as shown.
The lower portion of the lamp or the lanthorn proper, constructed as herein before
described, can be put over and taken off the lamp as one piece, and in order to give
the lanp absolute security against its being opened or tampered with, I attach the
lamp casing over and to the lamp by means of bayonet joints, as herein before
referred to. The said joints, of which one or more may be employed, consist as
follows: The ring A¹ which, as hereinbefore described, is securely attached to the
holder or upper part of the lamp casing, is formed with vertical slots a', Figure 1,
open at the bottom edge of the said ring and closed at the tops of the said slots,
except to a horizontal slot or notch a. The outer ring or collar d to which the
wires D are attached at the top is constructed with lugs d provided with studs d³
to correspond or fit the slots in the inner ring A'. When the lanthorn is to be put
on to protect the lamp, the collar d of the lanthorn is applied to the corresponding
ring A of the lamp holder, the studs d being passed within the slots in the
ring A, and by a horizontal movement in one direction the studs are locked into
the horizontal side notches a. By means of two separate projecting lugs a*, a*1,
one on each of the rings of the two parts of the lamp, these two parts are secured
together by a padlock a*2, and the lamp casing can be only taken off by the person
having the key. In lieu of the above described bayonet joint any other similar
joint may be employed which will render the casing, when locked, rigid and secure.
The lanthorn is provided at its two extremities with swivel rings X for suspending
or carrying the same.
On Sheet 2 of the Drawings, Figures 5, 6, and 7 represent three forms of my
improved lamps or lanthorns for lighting such places as warehouses, factories, or
private dwelling houses. In the vertical section, Figure 5, a lamp is illustrated in
which the casing is made as a convex metallic reflector H at the upper part, to
which the lower part or glass casing J is attached. The glass casing or globe J is

page_text: formed with a flange j which is securely fixed to the under side of the reflector H
by the thumb screw which passes through the lugs j¹, and by two other lugs
without such tightening screws formed on the edge of the reflector, the said screw
enabling the globe to be clamped to the reflector. A ring of india rubber k is
preferably interposed between the under edge of the reflector and the flange of the
globe, as shewn in the Drawing. The holder A containing the stem of the electric
lamp is attached to the top of the reflector H by the side supports h, the chamber C
of the incandescent light, which is shewn .in application in this form of lamp, being
suspended in the centre of the glass casing J.. A swivel ring is provided at the
top of the lamp holder for the suspension of the lamp. The electric lamp is shewn
of a form similar to that described and shewn with reference to Sheet 1 of the
accompanying Drawings, the same. letters of reference in Figure 5 representing
corresponding parts in Figure 2, Sheet 1 of the Drawings. Figure 6 represents in
vertical section a similar lamp or lanthorn in which the reflector H' is of a concave
shape, and to which the glass casing J¹ is secured by a bayonet joint which is made
by forming the ring or under part of the reflector H¹ with studs h³, and the outer
edge or thickened part of the globe J' with vertical slots terminating in hori-
zontally formed or slightly inclined notches or slots, so that upon applying the
globe to the under edge of the reflector and giving it an upward and side-way
inovement in accordance with the construction of the slots the globe. is firmly fixed,
and it may be provided with additional security by providing a padlock after the
manner of the lamp described and shewn with reference to Sheet 1 of the
Drawings, a ring of india rubber le being preferably interposed between the reflector
and the glass casing J', as shewn. As in the lamp, Figure 5, the reflector H¹ is
secured to the lamp holder A by brackets h¹*, the lower portion of the stem c of
the chamber C of the incandescent lamp being shewn in this modification
protruding through the top of the reflector, and situated centrally within the glass
globe.
•
Figure 7 represents the glass casing or lanthorn J2 of a deep or elongated form,
and with a conical reflector H projecting down thereinto and having the chamber C
of the incandescent electric light at the lower part thereof. The reflector H2 is
formed at its top with a flange h³, by which it is attached by rivets, soldering, or
by other means to the flange h' of the conical head piece h³, which is firmly
attached around the top part of the body of the lamp casing A*. The glass
shade J' is formed with a flange j³, which is supported and attached to the flange
of the conical part 1 by the clip springs, which clip the underside of the flange
of the said shade J; three or other convenient number of such springs may be
employed, and a ring k of india rubber is placed between the flange of the globe
and the flange of the conical part h³. The springs are soldered or rivetted to
the side of the conical part ho. In this modification the lamp holder A* is
necessarily extended in length, as shewn, to accord with the length of the reflector
and globe. Figure 8 represents a lamp of similar construction to the modification
illustrated in Figures 5 and 6, but which is adapted to be used as a portable lamp,
that is to say, a lamp which can be suspended at any point through which a
current passes, and so be moved from place to place without the necessity of cable
or conducting wires being attached to the said lamp; Figures 9 and 10 are details
of the apparatus in plan and elevation respectively; M is a bracket fixed by the
bolts m to a wall or other fixture M'; M is an arm formed with a hook m¹ at its
extremity; the bracket M is divided into two parts by insulating material m², the
arm M² being also divided in like manner by insulating material m². The top
portion of the lamp holder A is provided with a loop x, which is at its top divided
by insulating material, which forms part of the book; the two lower extremities of
the said hook being pivoted to the side of the lamp holder at ¹ by the contact
screws º. The conducting wires B are in contact with the extremities of the said
screws, and they lead from the said screws to the platinum wires and filament in
the chamber C for producing the light, the arrangement of the wires within the
holder being the same as is herein before described with reference to the previous

page_text: Figures. The bracket M-being permanently placed in circuit by the conducting
wires B', B, each wire of which is shewn in contact with the one half of the
bracket; the said portions of the bracket and the arm M' are in themselves
equivalent to two separate wires, owing to the interposition of the insulating
material m². When, therefore, the lamp is hung upon the hook of the arm M² the
two insulated ends *,*, of the loop are brought into contact with the two
insulated ends m³, m³, of the arm M², and the circuit is thus completed, so that the
lamp immediately becomes incandescent. In Figure 8 I have shewn the lower
part or casing of the lamp as formed with a concave reflector Hs attached to the
lower part of the lamp holder, and the glass casing J³ is formed with a flange j
which is supported and clamped to the underside of the reflecter by the screws h,
as described with reference to Figure 5.
With reference to another part of my Invention which relates to apparatus for
making and breaking contact, I have shewn, in front elevation in Figure 11 and in
vertical section in Figure 12, an apparatus which consists of a receptacle A of glass,
and which is supported upon a bracket B of wood or other suitable material fixed
to a wall or other support. The glass tube A is held between the upper and lower
parts B1, B2, formed of wood or other suitable material, which are connected to
and carried by the bracket B by the metallic conducting and holding screws C¹, C.
The receptacle A has fitted within it, towards the bottom part, a metallic conductor
a, which is in communication with the electric conductor c which has its end
screwed as shewn into the body of the metal a. A metallic bar or rod E passing
through the centre of the upper bracket B', and working air tight therein through
a stuffing box as shewn, can be operated either upwards or downwards to or away
from the conducting metal a. When therefore electric contact is desired to be
made, the rod E is lowered until its extremity is brought into contact with the
metal a, by which the electric current is established between the two conductors
C¹, C², the conductor C¹ being put into communication with the rod E through the
conducting metal 61 within the chamber B¹. I prefer, as shewn in the Drawing, to
form a recess in the top of the metal a, in which a drop of mercury lies, so that
the point of the rod E may not fail to come into contact when such contact is
required. In this manner the spark produced at the making or breaking of
contact takes place within the tightly closed glass tube, and thus the transmission
of ignition to inflammable gases in a mine or elsewhere is prevented.
Figures 13, 14, & 15 represent a modification of the apparatus for making and
breaking contact, Figure 13 is a front elevation, Figure 14 a horizontal section,
and Figure 15 a vertical section of the same. The apparatus consists of a
swivelling piece F, of wood, vulcanite, or other suitable conducting material. Tho
swivelling piece is constructed of two end pieces or holders f¹, for receiving the
ends of the insulated india rubber cables G, containing the two insulated
conducting wires g, g; the two portions f', fl of the tube are connected together
by a piece of glass tubing I, the ends of which are cemented within correspondingly
shaped holes in the inner ends of the blocks f¹, f', which blocks are further
connected by the caging wires f³, which also protect the glass tube I. The pin f
upon which the tube turns, is formed upon a ring fs, and the said pin f is centered
upou the hoop f, which is fixed rigidly to the wood work or bracket f³. A little
mercury Z is contained within the glass tube I, and acts in the following manner:
When the tube F is turned at any angle from the horizontal the mercury falls to
one end of the glass tube I, and connects the circuit between the two insulated
metal conductors g*, g*, which protrude from the inner ends of the piece f' into
the glass tube I. When the tube F is turned back to the horizontal position, as
shewn in the Drawings, the two exposed insulated conductors g* at the two ends of
the glass tube are both out of circuit; when therefore the tube F is turned
at an angle at either side, the conductors at that side at which the tube is turned
will be put in circuit. At the end opposite to that at which the circuit with a
lamp is completed, a resistance coil may be applied for the purpose of introducing
a resistance equal to that of a lamp when any one of the lamps in a series is shut

page_text: out of circuit, and in place of mercury a metallic ball may be substituted, or
several small metallic balls or metallic dust, such as filings, may be used. It is to
be understood that although I have shewn the "Swan" lamp as used in connection
with my improved lamp casings or holders, yet other forms of incandescent lamps,
such as those known as the "Edison" lamps or others may be substituted. It
is also to be understood that brackets or holders, having several points for
suspending incandescent lamps upon, may be constructed after the manner (that
is to say, with the same parts insulated) shewn and described with reference to
Figures 8, 9, and 10 of the appended Drawings.
Having now described and particularly ascertained the nature of my said
Invention and shewn some of the best mechanical contrivances with which I am
at present acquainted for carrying the same into practical effect, and whilst not
limiting myself to the precise mechanical arrangements, as the same may be
carried out without departing from the essential features of my said Invention, I
point out in conclusion that what I consider to be novel and original herein, and
therefore claim as the Invention secured to me by the hereinbefore in part recited
Letters Patent is,―
First. The arrangement or construction of the lamp casing or holder for
incandescent electric lamps, as hereinbefore described and shown at Figures 1 to 4
of the appended Sheets of Drawings.
Second. The arrangement or construction of the lamp casing or holder for
incandescent eléctric lamps, as hereinbefore described and shown at Figures 5 & 6
of the appended Sheets of Drawings.
Third. The lamp casing or holder for incandescent electric lamps, wherein a
deep conical reflector is used, having the incandescent light below the said
reflector, as hereinbefore described and shewn at Figure 7 of the appended Sheets
of Drawings.
Fourth. The portable electric lamp and brackets for carrying the same, whose
portions are insulated substantially as hereinbefore described and shown at
Figures 8, 9, and 10, of the appended Sheets of Drawings.
Fifth. The apparatus for making or breaking circuit, by which the electric spark
produced at the making or breaking of circuit takes place within a closed chamber,
thereby preventing the said spark.from igniting gas in coal mines or other places,
wherein an inflammable gaseous atmosphere may exist, or any mere modification
thereof, as hereinbefore described and shewn in Figures 11, 12, 13, 14, and 15 of
the appended Sheets of Drawings.
In witness whereof, I, the said David Graham, the younger, have hereunto
set my hand and seal, this Twenty third day of January, in the year of
our Lord One thousand eight hundred and eighty two.
DAVID GRAHAM, JR. (L.S.)