IMPROVEMENTS IN ELECTRIC ARC LAMPS
Year: 1883

page_text: 33
LETTERS PATENT to Sydney Pitt of Sutton in the County of Surrey for an
Invention of "IMPROVEMENTS IN ELECTRIC ARC LAMPS Communicated to
him from abroad by Nathan Huntley Edgerton, Electrician, a Citizen of the
United States residing at Philadelphia in the State of Pennsylvania
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of
the Commissioners of Patents on the 16th June 1883.
SYDNEY PITT of Sutton in the County of Surrey IMPROVEMENTS IN ELECTRIC
ARC LAMPS Communicated to mo from abroad by Nathan Huntley Edgerton,
Electrician, a Citizen of the United States residing at Philadelphia in the State of
Pennsylvania
My invention relates to a class of electric arc lamps in which the electrodes aro
in a vertical or nearly vertical position, in which the lower electrodo is fixed and
formed of refractory material, and in which the upper electrode is a carbon pencil
so set as to rest during the time when it is not in contact with the fixed electrode
by its own weight upon detaining pius of incombustible material which touch it a
short distance to the rear of its extreme front end and arrest its gravitative action.
My invention embraces the provision of improved means of application for the
carbon detaining pins, and of a separate magazine or pencil holder for the carbon
pencils constituting the upper electrode, by the employment of which not only are
all devices used to bold the carbon pencil and known as carbon clamps, clutches, or
holders dispensed with, but the utilization of the entiro substance of each carbon
point, and the continuous automatic supply of carbons, calculated to enable the
continuous running of the lamps for a predetermined period, enabled. My
invention, equally with that class of devices with which it is most nearly connected,
utilizes the passage of an electric current through the lamp and the attraction of
an electro-magnet energized thereby for an armature, to withdraw the upper.
electrode from the lower electrode and occasion the formation of a suitable are
interval through which the current is set up. It likewise avoids all feed shunting
devices and insures a constant length in the arc interval, the feed of the upper

page_text: electrodo taking place by gravity just as rapidly as the electrode itself is
consumed, and being, moreover, under such regulation as to render it impossible
that said upper electrode should approach the fixed electrode more nearly than a
predetermined distance during the entire period of the passage of the current.
In the accompanying drawings, Figure 1 represents in contral vertical sectional
front elevation a preferred form of lamp conveniently embodying my invention.
Figure 2 is a similar side elevational view of the same, representing however a
modified form of carbon feed tube. Figure 3 is a transverse sectional plan through
said modified form of feed tube, taken on the dotted line x-x of said Figure 2.
Figure 4 is a sectional elevational detail of a form of fixed electrode. Figure 5 is
a detail of the feed tube follower. Figure 6 is a horizontal sectional plan taken
on a plane projected on the dotted line y-y of Figure 1, and, Figure 7 is a similar
view on the dotted line -z of Figure 1. Similar letters of reference indicato
corresponding parts. In the drawings, A represents the casing for the electro-
magnet it being a box or cover suspended from a hanging frame 13, and from which
in turn is susponded the globe or bowl C of the lamp. The casing is preferably
cylindriform, and is composed of a metallic disk or head a to which is rigidly
connected a depending cylinder of metal ax which constitutes its sides or walls.
This depending cylinder is preferably provided with an external circumferential
flange a by means of which; as a device permitting of ready connection; the
casing is inclosed below by a base plate a' of insulating material, such for instance
as ebonite, the result of the application of which is that the casing becomes an
inclosed drum, so to speak. Connected in contact with the lower surface of the
base plate of the casing is what I term a globe plato D, it being a disk of metal
against the under face of which the globe fitted. Connection between the
cylinder of the casing the base plate and the globe plate is conveniently effected by
means of the screws E, and the removable application of the globe to the globe
plate by means of the look headed bolts F, all as clearly represented in Figure 2.
G is a U-shaped suspender or support for the fixed electrode, the same being
preferably formed of solidified graphite and connected with the insulating base
plate of the casing by screws 7 or kindred contrivances as also represented in
Figure 2. g* is a socket vertically erected from the suspender G and designed to
retain in fixed position the lower electrode H. This lower clectrode is formed of
refractory substance, such, for instance, as graphite, iridium, or zirconium, and it
may assume either the form represented in Figures 1 and 2 or the form represented
in Figure 4, in the former instance the entire point or electrode proper being
composed of incombustible material, while in the latter the electrode proper is
formed as a coating or deposit on a former of metal or other conducting material
which I have designated by h in said Figure 4, and which is represented as
spherical. I is what I term the carbon feed tube, it being a vertically erected
cylindric containing device or fixed magazine for containing the carbons con-
stituting the positive electrode. It is supported in insulating ferules i which in
turn are fixed in clamps b forming a part of the hanging frame The feed tube
passes vertically downward through and axially with respect to the casing and
extends a certain distance down within the globe. It has no contact with either
the head or the base plate of the casing or with the globe plate, but derives its
sole support from the hanging frame. It is also of such longitudinal extent as to
be adapted to contain two or more carbons of ordinary length, one above the
other, which aro froe, so far as any devices connected with them go, to gravitate
through it. J is a lifting sleeve, it being a tube of sufficiently larger interior
diameter to freely although closely surround the feed tube, and to be capable of a
'vertical movement with respect thereto.
At its lower extremity this lifting sleeve is formed into or provided with a
flanged collar j, preferably of brass, or of whatever material the lifting tube is
formed. Fitted through this flanged collar are one, two, or a series of detaining
pins K of iridium, platinum, or kindred refractory material. These pins are
preferably assembled in conically convergent relationship, and are designed to

page_text: control and arrest the descent of the carbons from out the feed tube. The lifting
sleeve passes through openings in both the head and base plate of the casing and
also in the globe plate, and is both electrically and mechanically connected to the
carbon feed tube through the instrumentality of a stud or studs d projected from
said feed tube and passing through a slot or slots k in the sleeve, while at its lower
extremity it is slightly prolonged beyond the lower extremity of said feed tube, as
represented in Figure 2. In Figure 2 I have represented a slightly modified
construction of carbon foed tube in which a lateral enlargement is made at its
upper portion, the object of which is to enable the placing of two carbons side by
side in said upper portion of the tube. The enlargement, midway of the tube,
contracts by means of an inclined surface into the unenlarged lower portion of the
tube, so that the oxterior carbon contained in the enlargement is deffected by said
inclined surface into said unenlarged lower portion when the other carbons have
descended to give place to it. L are spools connected together by means of a
yoke O suitably affixed to the head of the casing. P is a positive terminal applied
to the casing preferably upon its flange, and N is a negative terminal similarly
applied. W is a wire led off from the positive terminal to which the line-wire of
the exterior circuit is attached and wound around the spools in succession to form
the coils M, the extremity of which wire beyond the last spool is conducted through
a slot or opening g in the lifting sleeve to the feed tube to which latter it is firmly
connected R is a wire or other olectrical connection between the suspender a and
the negative terminal N. S is an armature of soft iron rigidly, although
adjustably, connected with the lifting sleeve at a point within the casing,
horizontally disposed with respect to the polos of the electro-magnet, and within
the area of influence of said poles. T is a metallic plug or follower which is
conformed to the interior of the carbon feed tube, and is connected therewith by n
flexible wire t.. This follower is put in place upon the top of the last carbon and
is adapted to gravitate with the latter through the tube, carrying its flexible wire
in after it. When the carbons are exhausted the follower will be at the bottom of
the tube, and is to be withdrawn by its wire so as to clean the tube of dust. This
follower, in addition to subserving the purpose of cleaning the feed tube, insures
electrical connection between the carbons and the tube. The follower is adapted
for use with a tube of the same diameter throughout. U, Figures 1 and 7, are two
pieces or plates of graphite or other material of high electrical resistance,
superimposed upon or otherwise applied to the base plate of the casing, and
extending from points below the armature respectively to the positive and negative
terminals, the arrangement being such as, in the event of an accidental stoppage
in descent of the carbon and consequent interruption of flow through the arc
interval, to occasion the setting up of the current through the plates and
armature (together constituting a circuit of high resistance) and so completely
through the lamp without causing an interruption in the running of other lamps
upon the same circuit, although the lamp in question be out of action. Having
now described a preferred forin of apparatus conveniently embodying my invention,
its operation is as follows:-Assume the carbon feed tube supplied with a suitablo
number of carbons calculated to supply the lamp for a predetermined time, and
further assume the lamp in connection with the line wires of an electrical circuit
through which for the time being no current is being passed under the above
circumstances the lifting sleeve, by its own weight and subject only to the
restraint of its stud and slot connection with the feed tube, has descended to the
limit of its downward movement, and has, of course, carried down with it its
armature, while the advance carbon electrode has gravitated through the feed tube
until its front extremity has encountered and rested upon the fixed electrode. In
this position of parts the set of the detaining pins is predetermined to be such as
to bring them just in contact with the carbon.
:
The result now of passing a current through the circuit of which the lamp forms
part, is, primarily, to energize the magnet within the casing and so to occasion the
attraction of the armature to it. The lift of the armature, however, occasions the

page_text: lift of the lifting sleeve, and, through the instrumentality of the detaining pins, of
the carbon or upper electrode-This lift of the sleeve is determinable by tho set
of the armature upon it, which set is such as to provide a space between the poles
of the magnet and the armature equal to the desired length of arc interval. The
instant that the electrodes are separated the light is established and continues as
a practically constant quantity, the are interval remaining uniform so long as the
current continues to pass,-it being impossible so long as the detaining pins romain
and so long as the armature is under the influence of the magnet for the movable
electrode to approach more nearly to the fixed electrode than a predetermined
distance. It will be readily perceived that so soon as one carbon is consumed a
succeeding carbon replaces it, so that the supply is practically constant. Upon the
discontinuance of the current through-the-line-wires the armature is released, and,
together with its lifting sleeve and the upper electrode, descends until the two
electrodes meet, or until the armature rests upon the plates of graphite and so
establishes a shunt circuit of high resistance, as hereinbefore explained. In
Figure 1 I have represented the slot q in the lifting sleeve as oblique, it being an
expedient of manufacture to form, as it were, a bearing for the lifting sleeve which
will thus resist end wise thrust of the latter possibly resulting from the vibration of
a floor from which the lamp is suspended. It has however the further advantage
that, occasioning as it does a partial rotation of the armature away from the poles
of the magnet during its downward movement and its resting in such partially
rotated position, the initial attraction of the energizing magnet upon the armature
will be greater and will thereforo occasion the more immediate and forceful
lifting of the armaturo than if the latter were in a right line below the poles.
While I have described and represented pins, strictly as such, as a detaining
device against which the conical extremity of the upper electrode bears and which
arrest its gravitative action, it is yet competent for me to employ knife edges,
points of various kinds, small plates, or even a conical collar, as a substitute for
these pins, it being, of course, understood that any such substitute contrivances
are to be made of incombustible material and are to be set to touch the carbon
pencil at a point intermediate between the apex and the base of its conical
extremity. I have both illustrated and described my lamp as having its electrodes
in a vertical position, and in such position the best results are to be obtained. It
is proper, however, for me to state that it would be possible to place the entire
device constituting my lamp in a horizontal position, and by the application of a
spring contrivance, or its equivalent, constantly feed the movable electrodes against
the detaining pins, the operation of the armature and lifting sleeve remaining
essentially the same, and further that this arrangement, while devoid of the
feature of a gravity feed of the movable electrode, would yet, as I regard it, bo
properly within the scope of my invention so far as the other elements and
combinations going to compose it are concerned. Incident to my invention are
the advantages that it enables the utilization of the entire current for illumination;
that the lamp requires little attention; that the light is steady and not liable to
constant fluctuation or occasional extinction; that, there being no base plate for
the lower electrode, there is but little shadow cast, and that the negative electrode
being practically indestructible the point of light remains fixed, forming a focussing
lamp. Having thus described my invention, I claim :-
First. In an electric are lamp in which a lower fixed electrode of irreducible
material is combined with an upper movable electrode being a carbon pencil free
to gravitato with respect to an arc interval between it and the fixed electrode
until entirely consumed, a fixed magazine or carbon feed tube which is adapted to
contain a series of carbon pencils arranged to successively gravitate therefrom and
which is uninfluenced as to its position in the lamp by the passage of the electric
current, substantially as set forth. Second,-In an electric arc lamp, the following
instrumentalities in combination, viz:-first, a fixed magazine or carbon feed tube
adapted to contain a series of carbon pencils so arranged as to successively gravitate
therefrom; second, detaining pins, points, or equivalent contrivances, adapted to

page_text: arrest the gravitative action of that carbon pencil which for the time being is the
upper electrode by bearing against its conical front extremity; third, a carbon
lifting sleeve to which said detaining pins are attached, fourth, an armature
applied to said lifting sleeve, and, fifth, an electro magnet in the circuit of the
lamp-the arrangement being such that the setting up of a current in the circuit
energizes the electro-magnet and thereby occasions the attraction of the armaturo,
the lift of the lifting sleeve, and the consequent lift of a carbon electrode to a
distance from the fixed electrode correspondent to the arc interval desired,
substantially as set forth. Third. In an electric arc lamp of the class herein
recited, the combination of a casing or kindrod containing device enclosing an
electro-magnet, a fixed magazine or carbon feed tube adapted to contain a series
of carbons arranged to successively gravitate therefrom, a carbon lifting sleovo
independent of the magazine, and an armature upon said lifting sleeve, the arrange-
ment being such that upon the energizing of the magnet the armature is attracted
and the sleeve lifted with respect to both magazine and casing, substantially as set
forth. Fourth. In an electric arc lamp of the class herein recited, the combination
of the carbon feed tube, the lifting sleeve, and the stud and slot connection
between said tube and sleeve, substantially as and for the purposes specified.
Fifth. In an electric arc lamp in which a lower fixed electrode of irreducible
material is combined with an upper movable electrode being a carbon pencil free
to gravitate with respect to an arc interval between it and the fixed electrodo, the
combination of two pieces or plates of graphite, positive and negative terminals
of the line wires with which the lamp is connected, and an armature adapted
upon its unrestrained descent to rest upon said plates and complete a circuit of
high resistance, substantially as and for the purposes set forth. Sixth. In an
electric arc lamp of the class herein recited, the combination of an electro-magnet
in the circuit of the lamp, a fixed carbon magazine, a carbon lifting sleeve which
is vertically movable with respect to said magazine, an armature directly attached
to said lifting sleeve, and suitable means for adjusting said armature upon said
lifting sleeve, substantially as and for the purpose set forth.
In testimony whereof I the said Sydney Pitt have hereunto set my hand and
seal this Sixteenth day of June in the year of our Lord 1883.
•
SYDNEY PITT
(LB)