IMPROVEMENTS IN ROOF LAMPS.
Year: 1876

page_text: LETTERS PATENT to John Thomas, of Jackson Road, Holloway, in the County
of Middlesex, for the Invention of "IMPROVEMENTS IN ROOF LAMPS.'"
PROVISIONAL SPECIFICATION left by the said John Thomas at the Office
of the Commissioners of Patents on the 12th October 1876.
JOHN THOMAS, of Jackson Road, Holloway, in the County of Middlesex.
"IMPROVEMENTS IN ROOF LAMPS.''
This Invention relates to improvements in the construction of that class of lamps
used for lighting railway and other carriages, and which are ordinarily known as
"roof lamps," the main objects of such improvements being to construct lamps, so
that ordinary petroleum having a comparatively low flashing point can be burned
therein with perfect safety; to facilitate the use of petroleum in roof lamps by
constructing the latter, so that the same can be cleaned, trimmed, and lighted easily
and efficiently by unskilled persons, and to construct such lamps so that the heat
arising from the combustion of the oil therein may assist in the ventilation of the
carriages in which they are placed.
The outer body of the lamp is of the usual cylindrical shape, and has a metal ring
fixed upon it near the top to act as a rain guard and to support the lamp in the
opening in the roof of the carriage. The oil container or cistern is of an aunular
form, and is fixed or supported at a short distance above the body of the lamp, and
surrounds the chimney casing or wind guard.
The oil is supplied to the burner by a syphon which is made by binding a
number of straight wires, and then bending them into the form of a syphon the
interstices between the wires forming channels for the oil to flow through. The
number, size, and length of the wires are so adjusted, that only such a given
quantity of oil is conveyed to the burner for consumption as the size and
number of wicks and height of the flame may require. The short leg of the syphon
is immersed in the oil cistern, the long leg being encased in a tube, such tube being
employed partly as a protection to the syphon, and partly to form a convenient
means for conveying the oil to the burner.

page_text: The supply of oil is further effected and regulated by a valve which is placed at
the bottom of the last-mentioned tube, and which valve is so arranged that in the
event of the lamp being put out by accident or otherwise the same will close and
thus stop the supply of oil to the burner. The valve is opened and closed by a
lever or levers which is or are actuated by a metal bar placed within the chimney
of the lamp; this bar is of a slightly curved form and is fixed to the chimney at
each of its ends. The effect of the heat from the flame produces a greater curvature
of the bar by reason of the expansion of the metal of which the same is formed, and
the cessation of heat by the flame being extinguished produces a contrary effect, the
movement of the bar consequently acting upon the lever and opening or closing
the valve as the case may be, and thus preventing any overflow of the oil.
The movement or action of the bar within the chimney is also made use of to
regulate the height of the flame in the following manner:-A short tube is made to
fit loosely on to the outside of the wick tubes at the upper part thereof. The said
wick tubes when raised and brought near the flame will lower the latter. The
loose tube is attached to a lever or levers which is or are actuated by the motion of
the bar within the chimney, so that if the flame becomes unduly high the bar
curves with the access of heat, communicates motion by means of the lever or
levers to the tubes round the wicks, raises the tubes, and thus lowers the flame.
The burner is supplied by preference with two wicks, and may have one deflector
or cone with the requisite slots or openings for the flame to pass through, or separate
deflectors or cones may be employed having one slot or opening in each. The wick
tubes are inclined outwards so that the flames project outwards from each other, so
as to prevent as far as possible any shadow from the body of the burner and the air
tubes. The base or bases of the deflector or cone, or deflectors or cones is or are
attached to the body of the burner by a hinge joint or joints, the base or bases
serving also as a support for the glass which surrounds the flame. Air is supplied
to the burner through a tube or tubes, such tube or tubes opening at the top into
the body of the lamp, and at the bottom into the body of the burner to which they
are attached.
The tubes are jointed or connected together by hinges in such a manner that the
body of the lamp may be lifted off the burner without disconnecting the parts, thus
greatly facilitating access to the wicks. The glass is of a cup or basin-like form,
and is fixed at the bottom to the base of the deflector or cone, and at the top fits
. closely to the reflector which is attached to the bottom part of the body of the
lamp. The reflector is fixed or suspended at a short distance below the body of the
lamp so as to leave a space between the two, such reflector being for the purpose of
throwing the light downwards, and also to serve as a base or support for the
metal chimney which is carried up to the top of the lamp from the centre of the
reflector.
The ventilation of the lamp is effected by means of a double casing of perforated
sheet metal, and an inner casing of metal not perforated. The top of the chimney
is terminated by a cross tube or T piece, the products of combustion not escaping
direct from the top of the lamp, but being delivered between the casing of plain
sheet metal and the inner perforated casing, and passing through the perforations in
the last-mentioned casing they come to the outer casing, and through the per-
forations therein into the surrounding atmosphere. The air for the burner also
passes through the perforations inwards to the air tubes.
The ventilation of the carriage is effected by admitting the air from the carriage
into the lower part of the lamp, a space or opening being left for that purpose
between the reflector and the body of the lamp as before mentioned. The air
becomes rarefied by the heat of the flame and passes out at the top into the
surrounding atmosphere, and its place is taken by a fresh supply from the interior
of the carriage.. The air from the carriage does not in any way mix with that
supplied to the burner, or that which comes from the burner, a separate channel
being provided for it, so that no inconvenience or unpleasantness can occur from
any down draught driving the products of combustion from the lamp into the

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Thomas in the Great Seal Patent Office on the 12th April
1877.
JOHN THOMAS, of Jackson Road, Holloway, in the County of Middlesex.
"IMPROVEMENTS IN ROOF LAMPS.""
My said Invention relates to improvements in the construction of that class of
lamps used for lighting railway and other carriages, and which are ordinarily known
as "roof lamps," the main objects of such improvements being to construct lamps
so that ordinary petroleum, paraffin, and other mineral oils having a comparatively
low flashing point can be burned therein with perfect safety; to facilitate the use
of petroleum, paraffin, and other mineral oils in roof lamps by constructing the latter
so that the same can be cleaned, trimmed, and lighted easily and efficiently by
unskilled persons, and to construct such lamps so that the heat arising from the
combustion of the oil therein may assist in the ventilation of the carriages in which
they are placed.
The outer body of the lamp is of the usual cylindrical shape, and has a metal ring
fixed upon it near the top to act as a rain guard, and to support the lamp in the
opening in the roof of the carriage. The oil container or cistern is of an annular
form, and is fixed or supported at a short distance above the body of the lamp, and
surrounds the chimney casing or wind guard.
The oil is supplied to the burner by a syphon, which is made by binding together
a number of straight wires, and then bending them into the form of a syphon, the
interstices between the wires forming channels for the oil to flow through. The
number, size, and length of the wires are so adjusted that only such a given
quantity of oil is conveyed to the burner for consumption, as the size and number
of wicks and height of the flame may require. The short leg of the syphon is
immersed in the oil cistern, the long leg being encased in a tube, such tube being
employed partly as a protection to the syphon and partly to form a convenient
means for conveying the oil to the burner.
The supply of oil is further regulated by a valve, which is placed at the bottom
of the last-mentioned tube, and which valve is so arranged that in the event of the
lamp being put out by accident or otherwise the same will close, and thus stop the
supply of oil to the burner. The valve is opened and closed by a lever or levers,
which is or are actuated by a metal bar placed within the chimney of the lamp.
This bar is of a slightly curved form, and is fixed to the chimney at each of its
ends. The effect of the heat from the flame produces a greater curvature of the
bar by reason of the expansion of the metal of which the same is formed, and the
cessation of heat by the flame being extinguished produces a contrary effect, the
movement of the bar consequently acting upon the lever and opening or closing
the valve, as the case may be, in the latter event preventing any overflow of
the oil.
The movement or action of the bar within the chimney is also made use of to
regulate the height of the flame in the following manner :-A short tube is made
to fit loosely on to the outside of the wick tubes at the upper part thereof. The
said wick tubes when raised and brought near the flame will lower the latter. The
loose tube is attached to a lever or levers, which is or are actuated by the motion
of the bar within the chimney, so that if the flame becomes unduly high the bar
curves with the excess of heat, communicates motion by means of the lever or
levers to the tubes round the wicks, raises the tubes, and thus lowers the flame.
The burner is supplied by preference with two wicks, and may have one
deflector or cone with the requisite slots or openings for the flame to pass through;

page_text: or separate deflectors or cones may be employed, having one slot or opening in each.
The wick tubes are inclined outwards, so that the flames project outwards from
each other in such a manner as to prevent as far as possible any shadow from the
body of the burner and the air tubes. The base or bases of the deflector or cone or
deflectors or cones is or are attached to the body of the burner by a hinge, joint, or
joints, the base or bases serving also as a support for the glass which surrounds the
flame. Air is supplied to the burner through a tube or tubes, such tube or tubes
opening at the top into the body of the lamp, and at the bottom into the body of
the burner, to which it or they is or are attached.
The tubes are jointed or connected together by hinges in such a manner that the
body of the lamp may be lifted off the burner without disconnecting the parts, thus
greatly facilitating access to the wicks. The glass is of a cup or basin-like form,
and is fixed at the bottom to the base of the deflector or cone, and at the top fits
closely to the reflector. The reflector, which is fixed or suspended at a short
distance below the body of the lamp so as to leave a space between the two, is for
the purpose of throwing the light downwards, and also serves as a base or support
to the metal chimney, which is carried up to the top of the lamp from the centre of
the reflector. The centre part of the reflector is movable so as to allow of a little
vertical movement to enable it to adapt itself to any slight variation in the depth of
the glass which surrounds the flame.
The ventilation of the lamp is effected by means of a double casing of perforated
sheet metal, and an inner casing of metal which is not perforated. The top of the
before-mentioned chimney is terminated by a cross tube or T piece, into the bottom
of which the straight part of the chimney enters, such straight part not being fixed
rigidly to the T piece, but in such a manner as to allow of any little vertical move-
ment of the chimney within the T piece, which may be caused by any such
variation of the glass, as already referred to. The products of combustion do not
escape direct from the top of the lamp, but are delivered between the casing of
plain sheet metal and the inner perforated casing, and passing through the per-
forations in the last-mentioned casing they come to the outer casing and through
the perforations therein into the surrounding atmosphere. The air for the burner
also passes through perforations inwards to the air tubes.
The ventilation of the carriage is effected by admitting the air from the carriage
into the lower part of the lamp, a space or opening being left for that purpose
between the reflector and the body of the lamp, as before mentioned. The air
becomes rarified by the heat of the flame and passes out at the top into the
surrounding atmosphere, its place being taken by a fresh supply from the interior
of the carriage. The air from the carriage does not in any way mix with that
supplied to the burner or that which comes from the burner, a separate channel
being provided for it, so that no inconvenience or unpleasantness can occur from
any down draught driving the products of combustion from the lamp into the
interior of the carriage, nor can the light be affected by the opening or closing of
the carriage door.
I will now proceed to refer to the annexed Drawings, from which the nature of
my said Invention will be more clearly understood.
Figure 1 is an elevation of the lamp, and Figure 2 a vertical section of the
same.
Figure 3 is a plan of the oil cistern and burner with the top plate of the
case (B2) enclosing the syphon removed.
Figure 4 shews the lamp open for trimming and lighting.
Figure 5 is a section of the burner; Figure 6 is a section of the syphon; and
Figure 7 is the end of the cross tube or Ṭ piece.
The sections in Figures 5 and 6 are taken at right angles to the section shewn in
Figure 2.
The same letters of reference indicate similar parts in the several Figures.
A is the body of the lamp; A¹, the metal ring; and A2, springs for steadying
the lamp when arranged in the roof of the carriage; B is the oil cistern; B₁, the

page_text: feeder screw; and B2, the case enclosing the syphon; C is the chimney casing or
wind guard, the upper part of which is perforated, as shewn in section in Figure 2;
D is the syphon; E, the oil tube; and F, the valve; G is the lever; and G¹, the
connecting rod; H is the before-mentioned metal bar; J, the regulating tubes on
the wick tubes; K, the wick tubes; and K¹, the spindles for winding the wick.
The lever and oil channels are shewn at L; M are the cones or deflectors; N is the
body of the burner; N¹, the base of the cones or deflectors; and N2, the joint con-
necting the base with the burner; O is the lamp glass. The air tubes are shewn
at P, and the hinges at P¹; R is the reflector, and R¹ the centre of the reflector;
S is the space for the inlet of air from the carriage, and S¹ the air channel; T is the
metal chimney; U is the cross tube or piece; V is the inner metal casing; W, the
inner perforated casing; and W1, the perforations; X is the outlet for the ventila-
tion of the carriage.
Having thus declared and ascertained the nature of my said Invention and in
what manner the same is to be performed, I would observe in conclusion that I do
not claim all the several parts of the before-mentioned apparatus separate and apart
from each other as being of my Invention, but what I consider novel and original
and therefore claim as constituting the Invention secured to me by the herein-before
in part recited Letters Patent are,-
First. The construction and arrangement of the jointed air tube for facilitating
access to the wick, and also the combination therewith of the syphon constructed
as aforesaid, substantially as and for the purposes herein-before set forth and
described.
Secondly. The construction and arrangement of apparatus for stopping the supply
of oil and regulating the height of flame, substantially as herein-before set forth and
described.
And, Thirdly. The combination of parts and mechanism in the construction of
roof lamps, substantially as and for the purposes herein-before described and set
forth, or any mere modifications thereof.
In witness whereof, I, the said John Thomas, have hereunto set my hand and
seal, this Twelfth day of April, in the year of our Lord One thousand eight
hundred and seventy-seven,
JOHN THOMAS. (L.S.)