Improvements in Electric Are Lamps.
Year: 1887

page_text: Date of Application, 13th May, 1887
Complete Left, 13th Feb., 1888
Complete Accepted, 12th May, 1888
Improvements in Electric Are Lamps.
We, FREDERICK GEORGE CHAPMAN, of 345 Mile End Road, in the County of
Middlesex, Electrician, and FRED MITCHELL DEARING, of 71 Cyprus Street, Old
Ford Road, Victoria Park, in the County of Middlesex, Printer, and Electrician and
WILLIAM GEORGE CHAPMAN, of 115 Uxbridge Road in the County of Middlesex,
Gentleman, do hereby declare the nature of our invention to be as follows:-
Our invention relates to electric arc lamps, and is designed to give a better distribu-
tion of light by reason of the shape of the arc, a steady light, with a fixed position of
the arc, and an easy and regular self acting feed and adjustment.
To effect this we construct our lamp as follows:-
We arrange the positive and negative carbon poles to meet one another at right
angles in the form of a T, the positive pole being thus practically divided into two
parts placed horizontally one on each side of the negative pole which is placed
vertically, the current being divided into parallel" through the two ends of the
positive pole and thence to the negative forming the arc.
By this arrangement of poles a peculiar shaped crater is formed on the underside
of the centre of the positive pole, where the ends of the two parts join. This
causes a form of arc exceptionally effective for distribution of light in a diffused
manner.
The two parts of the positive pole are fed together by spring pressure or weights
connected thereto by cords, or in other equivalent manner.
The carbons are so fitted in their guiding tubes that good electrical contact is
made, and so that they cannot turn on their axes when in work.
The lower negative carbon is self fed, which may be by spring pressure within
the bolding tube, pressing the conical end of the said carbon always home against a
retaining collar or ring as in a self feed candle, or in any other known suitable
manner, such as by clockwork.
The regulation for making and breaking arc and adjustment of the same is effected
by a solenoid, part wound in series in main current, and part shunt wound therefrom;
a differential action is thereby obtained upon the solenoid core for any changes in the
resistance of the main circuit, by break in the light or by variations in the distance
of the poles from one another..

page_text: The movements of the core of the said solenoid are communicated by suitable levers
to the vertically moving negative pole, and a dash pot may be used therewith to control
any sudden movement of the regulating device.
The lower negative pole is supported on a suitably insulated frame.
We may use a reflector of kaolin, asbestos, or other refractory substance above the
arc light.
•
FELL & WILDING,
1, Queen Victoria Street, London, E.C.,
Agents for the Applicants."
We, FREDERICK GEORGE CHAPMAN, of 345 Mile End Road, in the County of
Middlesex, Electrician, and FRED MITCHELL DEARING, of 71 Cyprus Street, Old
Ford Road, Victoria Park, in the County of Middlesex, Printer and Electrician, and
WILLIAM GEORGE CHAPMAN, of 115 Uxbridge Road, in the County of Middlesex,
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 :-
Our invention relates to electric are lamps, and is designed to give a better
distribution of light by reason of the shape of the arc, a steady light with a fixed
position of arc (thus enabling exact focussing for search or other lights) and an easy
and regular self-acting feed and adjustment.
To effect this, we construct our lamp as follows; and in order that our invention
may be the better understood we now proceed to describe the same in relation to the
drawings hereunto annexed reference being had to the letters and figures marked
thereon. Like letters refer to like parts in the several figures.
Fig. 1 represents a general elevation of our improved lamp.
Fig. 2 is a longitudinal section of one of the positive guiding tubes.
Fig. 3 is an elevation and plan of the retaining collar of the negative guiding
tube.
AA is the positive carbon divided into two parts meeting above the negative pole,
and arranged horizontally. B is the negative carbon, placed vertically, and under-
neath the point of contact of the two positive carbons, so that the poles meet one
another at right angles in the form of a letter T. The current, introduced at the
binding screw C, passes round one part of the solenoid D, and thence is divided in

page_text: parallel, either by suitable wires, or by the standards bb to the two parts of a
horizontal pole respectively, and thence to the negative carbon B, thus formning the
electric arc between their respective points; the current returns from the negative
pole through the mercury contacts E and the insulated framing F to the binding
screw G.
As a consequence of this arrangement of poles, a peculiarly shaped crater a is
formed on the under side of the centre of the combined pole, where the two ends of
the parts join. This causes a form of arc exceptionally effective for the distribution
of light in a diffused manner, and to a much greater extent than in the ordinary
arrangement of vertical poles. The position of the arc by reason of the character of
the feed of the negative pole being always towards the fixed position of the positive
pole, remains always in an absolutely fixed position, which is of great value where the
light has to be focussed or reflected.
The two parts of the positive pole A A are fed together by the pressure of a spring,
conveniently coiled in the drum H, the cords h h being taken from the periphery of
the said spring drum and attached to pins cc, which are inserted into metallic
plugs dd, travelling in the metal guiding tubes K K The points of the plugs d d
are wedged shaped, and press into suitable recesses in the rear of the positive carbon
poles A A, and prevent the latter from turning on their axes. The guiding tubes K
are slotted, so as to permit the pins c c to travel along the said tube, and thus
transmitting the pressure of the spring drum H by the metallic plugs d d to feed home
the two positive carbons A A, so that their extremities always remain in contact with
one another.
We may equivalently operate the automatic feed of these positive carbon poles by a
weight or weights, or other similiarly applied spring pressure. These carbons are
provided on the upper face with a groove which is advantageous in determining the
upper edge of the positive carbons to maintain the required shape of crater.
Rollersffkk press on the upper and under sides of the carbons providing smoother
travel to the carbons, and one pair K K is fitted with springs pressing upon the
carbons, which helps to ensure exceptionally good contact between the carbons and
the guiding tube. By reason also of the position of the carbons not being directly
above the electric are they and their connections are not exposed to such excessive
beat and we are enabled to bring the metallic contact of the guiding tubes much
nearer to the arc than is usual in the ordinary vertical pole, thus reducing the internal
resistance of our lamp. For the same reason also, we can, if desired, use without
danger of their splitting, carbons of any desired sectional area, so as to enable us
conveniently to use lamps of great power and to provide carbons with the least
possible resistance.
The lower negitive carbon B is also self_fed conveniently by the pressure of the
spring g within the metallic holding tube L. The said metallic holding tube L is
provided with a retaining collar or device M, of which we find the most convenient
form is as shown, in which small metallic strips m m, passing through holes in the
retaining collar M, are readily adjusted and secured by screws 11, working in slots
in the said strips, so that they can be pushed forward to press against the end of the
negative carbon as may be found desirable, and are readily replaced when burnt or
worn. The spiral spring g presses the negative carbon B, as it consumes, always
home against this retaining device similarly to the action of a self feed candle, or we
may adopt any other equivalent arrangement.
The regulation for making and breaking of the arc and for the adjusting of the
same as to distance is effected by the solenoid D D¹, part of which, D, is wound in
series in the main current, and the other part D is wound in a shunt circuit
therefrom. The differential action is thereby obtained upon the solenoid core for
any changes in the resistance of the main circuit by break in the light, or by variations
in the the distance of the poles from one another. The movement of the core N of
the said solenoid is communicated by the bell crank lever P to the vertical rod p, the
rocking arm Q, to the vertically moving negative pole tube L. The bell crank P is

page_text: E
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provided with a balance weight n, and the vertical rod p is insulated by a non con-
ducting coupling q.
In order to ensure reliable electric contact between the vertically moving negative
pole tube and the fixed frame F, through or along which the current is conducted to
the said pole, we provide a mercury cup R with metallic wire r therein, of sufficient
length to permit of the necessary vertical movement of the said tube without break
of metallic contact. We apply also a piston s attached to the vertical rod p, working
in a cup of oil T, to act as a dash pot, to control any sudden movement of the
regulating device. We may use a deflector or protector V of kaolin, asbestos, or
other refractory substance above the arc light, to protect the upper framing and parts
from the heat of the arc.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1st. In an electric arc lamp the combination therein of the positive and negative
poles at right angles to one another in the form of the letter T, the negative pole
being presented to the centre of the positive pole and the two parts of the positive
pole being automatically fed from either side towards the point of waste of the
electric arc.
2nd. In such an electric arc lamp, the guiding and feeding of the two parts of the
positive pole by the rollers fk and the plugs d d, in combination with a spring drum H
and connections h, substantially as described.
3rd. In such an electric arc lamp, the apparatus for feeding and controlling the
negative pole, consisting of guide tube L, adjustable retaining device M m m, mercury
contacts E and the feed spring 9, the whole tube operated for adjustment by the
solenoid D D¹ and connections, substantially as described.
4th. In such an electric arc lamp the construction of the carbons with grooved
upper surface, substantially as and for the purposes specified.
5th. The general construction and arrangement of the electric arc lamp substantially
as described and illustrated herewith.
Dated this 13th day of February 1888.
FELL & WILDING,
Agents for the Applicants.