Year: 1887

page_text: Date of Application, 3rd Sept., 1887
Complete Specification Left, 4th June, 1888
Complete Specification Accepted, 3rd Sept., 1888
I, AUGUSTUS GEORGE VERNON HARCOURT, of Cowley Grange, Oxford, in the
County of Oxford, Gentleman, do hereby declare the nature of this invention to be
as follows
My invention relates to improvements in oil lamps whereby a definite and regulated
amount of light may be obtained so as to be conveniently used as a standard in
measuring other lights in photo-metric observations.
My lamp is constructed as follows:-
I provide a vessel, which may conveniently be of glass and of the form and
dimensions of an ordinary spirit lamp, to contain the oil or liquid with which it is fed,
and which may conveniently be "Pentane" obtained by purification and repeated
rectification from American petroleum. This liquid is so volatile that it is converted
into gas within the burner, the wick serving only to bring the liquid to a part of the
tube where the heat is sufficient to evaporise it at the required rate. I mount this
lamp upon a stand, provided with levelling screws. To the lamp is fitted a cap
surmounted by a tube in which a wick is moved up and down by the ordinary
arrangement of a double spiked wheel turned by a handle.
Around the upper part of this tube, whose diameter may be about a quarter of an
inch and its length six or seven inches, is a second tube of about one inch in diameter
and four inches in length, which serves as a jacket to keep more constant the
temperature of the inner tube and to guide the air current, upon which the steadiness
and brightness of the flame of the lamp depend. The two tubes are joined by flat
plates above and below and constitute the burner of the lamp.
Attached to the inner tube by branches is a gallery carrying an opaque or metal
chimney, which surrounds both the burner and the lower part of the flame. Above
the burner, this chimney is reduced to a diameter intermediate between that of the
aforesaid outer and inner tubes of the burner, and terminates at a short distance above
the burner. The upper part of the flame is again enclosed by a continuation of this
opaque or metal chimney, of the same diameter as the lower part, but which is

page_text: enlarged in diameter towards its upper end. This upper portion of the chimney is
connected with the lower chimney by curved metal bands, conveniently two in number
and sufficiently removed from the flame on either side as not to affect it. Through
the space thus left between the upper and lower metal chimneys the central part of the
long flame which the burner produces is alone visible. The attachment of these bands,
connecting the upper to the lower chimney, is adjustable, so that the opening through
which the central part of the flame is seen may be made larger or smaller as desired.
By simple means, such as an adjustment screw, this opening can be set quickly and
accurately to such sizes as will give exactly the light of half a candle, one candle or
less or more as desired.
At opposite sides of the lower part of the upper chimney are two narrow slots,
through either of which the tip of the flame may be seen; and the construction of
the lamp is such that the light emitted through the opening between the two chimneys
is the same whenever the tip of the flame can be seen through the said slots.
The bands connecting the two chimneys are of half the width of the tube that
surrounds the flame. When these bands are placed in a plane perpendicular to the
bar of the photometer, a point midway between their edges and at half the height of
the flame is to be taken as that from which the distances are measured.
Suitable attachments are provided for carrying a plumb line, to serve in setting the
lamp vertical, and for carrying a small piece of glass by means of which it may be
observed from any position whether the tip of the flame is within the slot or not.
Dated this 3rd day of September 1887.
FELL & WILDING,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicant.

page_text: 1, AUGUSTUS GEORGE VERNON HARCOURT, of Cowley Grange, Oxford, in the County
of Oxford, Gentleman, 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 improvements in oil lamps whereby a definite and regulated
amount of light may be obtained, so as to be conveniently used as a standard for
measuring other lights.
My lamp is constructed as follows:-
"
I provide a vessel, which may conveniently be of glass and of the form and
dimensions of an ordinary spirit lamp, to contain the oil or liquid with which it is fed
and which may conveniently be "Pentane obtained by purification and repeated
rectification from American petroleum. This liquid is so volatile that it is converted
into gas within the burner, the wick serving only to bring the liquid to a part of the
tube where the heat is sufficient to cause it to evaporate at the required rate.
In order that my invention may be the better understood I now proceed to describe
the same in relation to the drawings hereunto annexed, reference being had to the
letters and figures marked thereon.
Figure 1 represents a sectional front view of the lamp.
Figure 2 represents a side view of the lamp.
Figure 3 represents a plan of the lamp.
Figure 4 represents the small collar which is to be used when the half candle
gauge is employed. The collar is slipped over the small tube surrounding the lower
part of the flame and the measurement with the gauge is to be made from the upper
edge of this collar.
I mount a glass vessel a upon a stand b, provided with levelling screws c. To the
vessel is fitted a cap d surmounted by a tube e in which a wick is wound up and down
by the ordinary arrangement of a double spiked wheel f turned by a handle.
Around the upper part of this tube, whose diameter may be about a quarter of an
inch and its length six or seven inches, is a second tube g of about one inch in diameter
and four inches in length, which serves as a jacket to keep more constant the
temperature of the inner tube, and to guide the air current upon which the steadiness
and brightness of the flame depend. The two tubes are joined by flat plates h above
and below, and constitute the burner of the lamp.
Attached to the inner tube by branches is a gallery j carrying a metal chimney k
which surrounds both the burner and the lower part of the flame. Above the burner
the part k¹ of this chimney is reduced to a diameter intermediate between that of the
aforesaid outer tube g and inner tube e of the burner, and terminates at a short distance
above the burner. The upper part of the flame is again enclosed by a continuation
of this metal chimney, which is of the same diameter as the lower part, but is
enlarged in diameter towards its upper end.
This upper portion of the chimney is connected with the lower chimney by curved
metal bands m, conveniently two in number, and sufficiently removed from the flame
on either side as not to affect it.

page_text: Through the space thus left between the upper and lower metal chimneys, the
central part of the long flame which the burner produces is alone visible.
The attachment of these bands connecting the upper to the lower chimney is
adjustable by set screws n, so that the opening through which the central part of the
flame is seen may be made longer or smaller as desired.
By simple means, such as an adjustment screw, or preferably by means of cylindrical
gauges of the same diameter as the tubes which they separate, this opening can be
set quickly and accurately to such sizes as will give exactly the light of half a candle,
one candle, one and a half candles, or values intermediate between these as desired.
At opposite sides of the lower part of the upper chimney are two narrow slots o
through either of which the tip of the flame may be seen; and the construction of
the lamp is such that the light emitted through the opening between the two chimneys
is the same whenever the tip of the flame appears opposite the slot, whether towards
the lower or the upper end.
The bands m connecting the two chimneys are of half the width of the tube that
surrounds the flame. When the lamp is vertical so that these bands are in a plane
perpendicular to the horizontal bar of the photometer, a point in the plane containing
the edges of the bands nearest to the photometric disc, midway between these edges,
and at the height of the centre of the aperture through which the luminous flame is
visible, is to be taken as that from which distances are to be measured. This point
represents the zero of the usual photometric scale.
In order to easily obtain the plane in which this point lies, two slots s are cut in the
bands m on the side nearest the disc and into these slots a flat piece of metal fits of
the same thickness as the depth of the slots,-the point from which distances are
measured lies on the surface of this piece nearest to the disc.
Suitable attachments are provided for carrying a plumb line p to serve in setting
the 1 p vertical, and for carrying a small piece of coloured glass fitting in the plumb
line ockett so as to stand opposite to the slot o. By reflection from or direct vision
thigh this glass it may easily be observed whether the tip of the flame is within the
" or not.
The height of gauges which find produce, when burning "Pentane," a light
equivalent to a half, one, or one and a half, standard English parliamentary candles,
is respectively 7, 16, 27.5 m.m.
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 :-
1st. The construction of a lamp to enable it to burn a highly volatile combustible
liquid, producing a constant light, substantially as and for the purposes described.
2nd. In such a lamp, the combination of a jacketed supply tube with one or more
concentric tubes with intervening air spaces to produce the following effects:
(a) A distribution of temperature along the tube containing the wick, causing
any desired constant height of flame to be produced by raising or lowering
the wick.
(b) A steady and bright flame, owing to its being situated in the axis of a uniform
and rapid current of warm air.
3rd. The construction and combination of parts in a lamp to enable unmixed
pentane vapor to be burnt without charring the wick in normal use, and so as to
produce a uniform standard light substantially as described.
Dated this 4th day of June 1888.
FELL & WILDING,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicant.