Improvements in Oil Lamps.
Year: 1891

page_text: Date of Application, 19th Oct., 1891
Complete Specification Left, 19th July, 1892-Accepted, 20th Aug., 1892
PROVISIONAL SPECIFICATION.
Improvements in Oil Lamps.
I, WILLIAM SNELGROVE, of Clent Cottage, Harborne, in the County of
Stafford, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to the construction and arrangement of oil lamps, and its
object is to permit the oil reservoir to be placed in the base or at some considerable
distance below the burner so as to avoid the shadow which is at present cast
by the reservoir, and to secure other advantages that are well known to manu-
facturers.
In one mode of carrying my invention into effect, I arrange the oil reservoir or
vessel in the base of the lamp and mount the burner on a stem or pillar at a con-
siderable distance above it. This stem or pillar is hollow and forms part of the oil
reservoir, and the oil fills the stem and enters a small wick chamber just below the
burner.
The oil reservoir, that is, the outer case of it, is arranged with an interior part
to form an annular trough which contains mercury. A cup or bell shaped vessel
dips into this mercury trough and the interior of the reservoir is thus closed by a
mercury seal. The interior of the cup or bell shaped vessel is open to the external
atmosphere through the base, and its external surface serves as a movable and air
and oil tight bottom to the oil reservoir.
A suitable guide or guides are provided to cause the vessel to rise and fall with
its edges in the mercury, but free from friction at the sides. This guide may con-
veniently project from the bell into a suitable socket in the base of the lamp, and
check nuts may be applied to limit its lift.
In the hollow stem or pillar 1 introduce a spring which acts in tension, one end
being fixed to the hollow stem and the other end to the top of the cup or bell
vessel.
This spring is strained to a tension depending on the column of oil to be supported,
and it is so proportioned that a constant or nearly constant level is maintained in
the small vessel at the top of the stem or pillar. When oil is poured into the
reservoir through the top of the stem or pillar, the level rises until the pressure of
the column on the available area of the cup or bell shaped vessel becomes greater
than the tension of the spring, and then the spring yields and the vessel or movable
bottom moves down. The spring is so proportioned that the movable bottom travels
through its whole range with a small change in level of the oil column, so that the
level in the small chamber at the top remains nearly constant while oil is being
poured in or varies through a permissible range. When the lamp is burning,
therefore, oil is supplied from the base to any height required, and keeps the upper
level nearly constant. It is to be understood that the mercury seal keeps the
movable bottom oil tight, and the height of this mercury seal will be about one
fourteenth or one fifteenth of the height of the oil column depending on the density
of the oil.
One inch of mercury column will thus balance about 14 or 15 inches of oil column,
and so a movable bottom is rendered possible.
It is also to be noted that the spring pressure or tension increases with the fall
of the cup or bell bottom and the height of oil column operating on that bottom
also increases so that the unequal action of the spring is compensated for, and a
fairly constant upper oil level is maintained while the oil lasts in the reservoir.
To prevent any chance of loss of mercury from the mercury seal, the part forming

page_text: the interior wall of the annular space or the disc joining that wall, is perforated or
made open and the edge turned in to prevent spilling.
This
To prevent any oscillating action of the oil column when lifting or moving the
lamp, a plate is placed in the stem or pillar, and the oil is caused to pass through a
small hole in this plate so as to interpose a hydraulic resistance to movement.
hydraulic resistance may be introduced at any point between the main reservoir and
the stem or upper chamber.
To enable oil to be freely poured into the lamp reservoir from above, a flap,
check or other valve is provided which opens or is opened, and allows oil to be
poured in from above but remains closed to pressure passing from below.
Means are also provided to change the adjustment of the spring.
Modifications of this arrangement may be adopted; thus the bell or cup shaped
vessel may act like a gas holder containing oil above a mercury seal-and a spring
may press down this holder and thus force oil through a pipe to the upper oil level.
Levers may be used to equalize the varying pressure of the spring. Any con-
venient type of spring may be used for the purpose, but I prefer a tension spiral
spring or springs.
The cup or bell vessel may also be adapted to compress air to raise the oil
column.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Oil Lamps.
I, WILLIAM SNELGROVE, of Clent Cottage, Harborne, in the County of
Stafford, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention relates to the construction and arrangement of oil lamps, and its
object is to permit the oil reservoir to be placed in the base or at some considerable
distance below the burner so as to avoid the shadow which is at present cast
by the reservoir, and to secure other advantages that are well known to manu-
facturers.
.
In the accompanying drawing is shown a vertical section of one mode of carrying
my invention into effect in which I arrange the oil reservoir or vessel B in the base
of the lamp and mount the burner Hon a stem or pillar D at a considerable distance
above it. This stem or pillar D is hollow and forms part of the oil reservoir B, and
the oil fills the stem and enters a small wick chamber F just below the burner.
The oil reservoir, that is, the outer case of it B', is arranged with an interior
part B to form an annular trough C which contains mercury. A cup or bell
shaped vessel A dips into this mercury trough, and the interior of the reservoir B
is thus closed by a mercury seal.
The interior of the cup or bell shaped vessel A is open to the external atmosphere
through the base, and its external surface serves as a movable and air and oil tight
bottom to the oil reservoir.
==
A suitable guide A' or guides is or are provided to cause the vessel A to rise and
fall with its edges in the mercury contained in the annulus C, but free from friction
at its sides. This guide A' conveniently projects from the bell into a convenient
socket B³ in the interior part of the base of the lamp, and check nuts may be
applied to limit its lift, but these are dispensed with in the example shown in the
drawing the rise of the bell vessel A being checked by the top of B¹.
In the hollow stem or pillar D I introduce a spring E which acts in tension, one
end being fixed to the hollow stem at its upper part and the other end to the cup

page_text: or bell vessel. This spring is strained to a tension depending on the column of oil
to be supported, and it is so proportioned that a constant or nearly constant level is
maintained in the small vessel F at the top of the stem or pillar. When oil is
poured into the reservoir through the top of the stem or pillar D, the level rises
until the pressure of the column on the available area of the cup or bell shaped
vessel A becomes greater than the tension of the spring E. and then the spring E
yields and the vessel or movable bottom A moves down. The spring is so pro-
portioned that the movable bottom A travels through its whole range with a small
change of level of the oil column, so that the level in the small chamber F at the
top remains nearly constant while oil is being poured in or varies through a
permissible range. When the lamp is burning, therefore, oil is supplied from the
base B to any height required, and keeps the upper level nearly constant.
It is to be understood that the mercury seal in the annulus Ċ keeps the movable
bottom air tight, and the height of this mercury seal will be about one fourteenth
or one fifteenth of the height of the oil column depending on the density of
the oil.
One inch of mercury will thus balance about 14 or 15 inches of oil column, and
so a movable bottom is rendered possible.
It is also to be noted that the spring pressure or tension increases with the fall of
the cup or bell bottom A and the height of oil column_operating on that bottom
also increases, so that the unequal action of the spring E is compensated for, and a
fairly constant upper oil level is maintained while the oil lasts in the reservoir.
To prevent any chance of loss of mercury from the mercury seal, the part forming
the interior wall of the annular space or the disc joining that wall, perforated or
made open and the edge turned in as at I to prevent spilling.
The guide socket B or the guide projection A¹ is fluted or flattened to allow
sufficient access of air or a hole made to allow of such access.
To prevent any oscillating action of the oil column when lifting or moving the
lamp, a plate G is placed in the stem or pillar D, and the oil is caused to pass
through small holes in this plate so as to interpose a hydraulic resistance to move-
ment. This hydraulic resistance may be introduced at any point between the main
reservoir and the stem or upper chamber.
To enable oil to be freely poured into the lamp reservoir from above, a flap, check
or other valve G is provided which opens or is opened, and allows oil to be poured
in from above but remains closed to pressure passing from below.
In the drawing the valve G serves the purposes of hydraulic check plate and
valve to permit oil to be poured in.
Means are also provided to change the adjustment of the spring E, such as a
rotating screw which is not shown in the drawing.
Modifications of this arrangement may be adopted; thus the bell or cup shaped
vessel may act like a gas holder containing oil above a mercury seal and a spring
may press down this holder and thus force oil through a pipe to the upper oil level.
Levers may be used to equalize the varying pressure of the spring. Any con-
venient type of spring may be used for the purpose, but I prefer a tension spiral
spring or springs.
The cup or bell vessel may also be adopted to compress air to raise the oil
column.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what
I claim is :-
:-
1. In an oil or like lamp a device to maintain a nearly constant level in a small
wick chamber consisting of a movable bell or cup shaped bottom dipping into
mercury and producing a mercury seal the said bottom being operated by spring
or weight to sustain the oil column substantially as and for the purposes hereinbefore
described.

page_text: 2. An oil or like lamp arranged and operating substantially as described reference
being made to the accompanying drawings.
Dated this 18th day of July 1892.
MARKS & CLERK,
13, Temple Street, Birmingham, Agents for the Applicant.