Improvements in and relating to Electric Arc-lamps.
Year: 1895

page_text: Date of Application, 16th Apr., 1895-Accepted, 8th June, 1895
COMPLETE SPECIFICATION.
Improvements in and relating to Electric Arc-lamps.
We, EDWARD HAROLD CROSBY, of 259 Washington Street, Boston, in the
State of Massachusetts, United States of America, Dramatic Editor, and OTIS
MADISON SHAW, of 63 Court Street, Boston, in the State of Massachusetts,
United States of America, Counsellor-at-Law, 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 improvements in electric arc lamps whereby the
construction is greatly simplified and the cost very much reduced while the
efficiency of the lamp is increased. An especial object of the invention is to
produce a portable arc lamp adapted for use on an incandescent circuit and provided
with an automatic feed for the carbons whereby the flickering incidental to
ordinary lamps of this class is prevented.
Moreover our improved feed so locks the carbons that the lamp may be used in
any desired position without disturbing the arc.
In the accompanying drawing forming part of this Specification,
Figure 1 is an elevation of our improved lamp, the box or holder being in
section;
Figure 2 a sectional view on line 2-2, Figure 1; and
Figure 3 an elevation illustrating a modification in the construction of
the lamp.
Like letters and figures of reference indicate corresponding parts in the different
figures of the drawing.
In the drawing, A, represents a containing box of insulating material in which
is mounted an electro-magnet B.
In each upper corner of the box a metallic socket d, is secured by means of a
plate b.
Binding posts or terminals g, are provided for connection with the line wires.
A wire connects one socket with the post or terminal 7 and a wire i connects the
companion post with the electro-magnet, from which a wire q leads to the opposite
socket d.
Metallic spring arms m arc bent at or to form \-springs the short arms of which
are secured to the plates b. These arms are slotted longitudinally as indicated at
the left in Figure 1.
A tubular follower t is fitted to seat in each socket d and is adapted to hold the
upper end of the carbons C which are secured therein by set screws, p, which pass
through the slot in the spring arms m and serve to guide the said followers.
Each arm has a ring on its lower end through which the carbon passes
loosely, so as to permit slight lateral movement. The current passes through these
spring arms and the rings into the carbons, adjacent to their free ends.
On the bracket 50, which supports the magnet, are journaled two meshing
gears, y, z. The gear, y, is hollow and a helically-wound spring 21 is mounted on
its arbor, this spring tending to rotate the said gear in the direction indicated by
the arrow in Figure 1.
:
To each gear is rigidly secured a radiating arm 22. These arms are slotted
at 23 in their outer ends and engage with pins 24 respectively secured to the
ollowers t.
7

page_text: To the armature 35 of the magnet, a bar 15 is pivotally connected. One end of
this bar (see Figure 2) is connected by a coiled spring 18 with an adjusting
screw, 19, mounted in a lug 20 on the box A. The said bar is pivoted at 17 to a
hanger within the box. A rod 16 is fitted to slide vertically in the said hanger
and is connected to the outer end of the said bar.
2
The lower end of the rod 16 has a forked head 30 in the arms of which rollers 31
of porcelain or other insulating material are journaled in such a position as to
engage the carbon rods C, below the rings k.
Any suitable resistance which may be adjusted or varied may be interposed in
the circuit. As the resistance is reduced and the current increases, the current
from the line entering at the post or terminal passes into the adjacent coil of the
magnet; thence through wire q, socket d and spring arm in and its ring k into the
carbon held therein. Thence to the opposite carbon and its holder through
the return at the post or terminal 9.
11
The magnet being thus excited, its armature 35 is drawn up, forcing the rod 16
downward against the pull of the spring 18, and drives the rollers 31 against the
carbons C, forcing the said carbons outward in opposition to the spring arms m,
thus separating the points of the said carbons and "striking" or forming an arc.
As the length of the arc increases and the current in the magnet correspondingly
decreases the spring 18 will act to draw up the rod, 16, which will lessen the
tension between the carbons and the rings k sufficiently to permit the spring 21 in
the gear y to operate and rotate said gears. This will move the followers t down-
ward and feed the carbons correspondingly, until they have approached so near
that the current in the magnet has increased sufficiently to again operate the
head 30 and spread said carbons as before.
These movements are so nearly instantaneous that an arc of substantially
constant size is maintained. No jumping or flickering of the light is to be
observed and the carbons are locked against feeding by gravity by the tension of
the spring arms and the head 30.
The lamp being portable and adapted for use on incandescent circuits in any
position, it is of great value for use in scenic effects where the well-known lime or
calcium lights are now used.
In the form shown in Figure 3, tubes 40 are employed rigidly secured to a
base 42 by holders 41. The carbons slide in the said tubes and are pushed' by
springs 43 on the tubes.
The head or plunger 30 has feet 39 which engage with
the carbons in opposition to said springs to form the arc and also serve to feed' said
carbons downward.
The plunger rod 36 slides in a tube 38 and carries the armature 35, said rod
being forced upward by a spring 37.
A dog 44 on the tubes engages the carbons and prevents them from accidentally
slipping inward when the lamp is inverted. The operation of this device is
substantially the same as described for the first form but the feed is not so' constant
and effective.
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
1
1st. Two diagonally arranged carbons mounted to slide in suitable supports and
pushed towards each other by means of springs, in combination with an electro-
magnet and a non-conductive material actuated by the armature of said magnet
for spreading said carbons against the pressure of said springs.
2nd. In an electric arc lamp, two carbons arranged diagonally and pushed
towards each other by means of springs, in combination with an electro-maguet
and a non-conductive material actuated by the armature of said magnet and
arranged to spread said carbons in opposition to their springs and feed the saine
longitudinally.
3rd. In an arc lamp, two diagonally-arranged supports, carbons, therein pushed

page_text: towards each other by means of springs, an electro-magnet in the circuit of which
said supports are interposed, and an insulating material actuated by the armature
of the said magnet and engaging the said carbons in opposition to the said springs,
substantially as, and for the purpose, set forth.
4th. In an arc lamp, two diagonally arranged carbons mounted to slide in tubular
supports of conducting material and having lateral movement, in combination
with springs pushing the free ends of said carbons towards each other, an electro-
magnet in the circuit of which the said supports are interposed, mechanisın
actuated by the armature of the said magnet for engaging the carbons in
opposition to the springs and arranged to consecutively spread them, lock them
against gravitational movement, and feed them towards each other at pre-
determined points in the variation of the electric current.
5th. In an arc lamp, two diagonally-arranged carbons having their adjacent
ends normally pushed into engagement by means of springs, an electro-magnet,
mechanism actuated by the said magnet for spreading the said carbons against
the pressure of the said springs, and mechanism for automatically feeding the said
carbons longitudinally when the tension of said spreading mechanism is lessened,
substantially as, and for the purpose, set forth.
6th. In an arc lamp, the combination of the spring pushed carbons, the magnet,
the insulating plunger actuated by the armature of said magnet, the spring-
actuated gears, and connections between the gears and carbons whereby the said
carbons may be fed when the current in the magnet is lessened substantially as
described.
7th. In an arc lamp, two diagonally arranged carbons movable both laterally
and longitudinally by means of springs, an electro-magnet, and mechanism actuated
by said magnet and operating in opposition to the said springs for spreading the
said carbons to form or "strike "and maintain the arc.
Dated this 16th day of Annil 1905
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicants.