IMPROVEMENTS IN ELECTRIC-LAMPS OR LIGHTING APPARATUS
Year: 1882

page_text: LETTERS PATENT to William Robert Lake of the Firm of Haseltine, Lake
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"IMPROVEMENTS IN ELECTRIC-LAMPS OR LIGHTING APPARATUS." A communi-
cation from abroad by James John Wood, of Brooklyn, New York, United
States of America.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 31st May 1882.
OR
WILLIAM ROBERT LAKE of the Firm of Haseltine Lake & Co. Patent Agents
Southampton Buildings London. "IMPROVEMENTS IN ELECTRIC LAMPS
LIGHTING APPARATUS. A communication from abroad by James John Wood
of Brooklyn New York United States of America.
This Invention relates to arc lamps and to devices for cutting a faulty lamp out
of circuit when its arc fails, or when the arc becomes abnormally long by failure of
the feeding mechanism or by other causes.
When a number of arc lamps are circuited in a direct series it is well known
that the arc in each must be kept practically uniform and of normal length, for
should an abnormally long arc be formed in any one lamp, its resistance would
correspondingly reduce the action of all the other lamps in the circuit, and if the
arc in the faulty lamp should continue to increase in length it would tend from its
great heat and flaming condition, to ignite surrounding woodwork or other inflam-
mable material and thus cause fires; or by the great resistance which it would
present in the circuit would finally tend to damage the lamp by burning the insu-
lating material Lamps have therefore been provided with devices to prevent
these contingencies, which devices are usually termed "automatic cut outs" or
'safety cut outs."
"
Heretofore this cut out has been effected by the action of a magnet in a shunt,
which, when it became abnormally attractive owing to abnormal length of arc,
moved its armature, closed a contact and thereby established a short free circuit
independent of the arc, so as to extinguish the abnormal arc and switch the faulty.

page_text: lamp out of circuit without interrupting the current to, or affecting the action of
the other lamps in the series.
The shunt-magnet heretofore used to operate the cut-off has been a special one
distinct from and additional to the magnet for regulating the feed of the carbons,
whereas, according to the said Invention I employ a shunt-magnet in the carbon
regulator, and I combine my cut-off devices with the said regulating magnet and
thus produce a safety cut-off in a simple and efficient manner.
Again in the former case, the cut-off switch is kept closed by the abnormal
attraction of the shunt-magnet and opens as soon as the attraction becomes normal
and thus tends to again establish the arc in the faulty lamp. According to the said
Invention however, the abnormal attraction of the shunt-magnet acts simply to
trip or release a catch or latch and thereby release the cut-off switch which then
springs shut and thereby closes the safety branch circuit, thus permanently cutting
out the faulty lamp.
The said Invention also comprises in addition to certain details the combination
with the automatic safety switch of a hand switch for voluntarily placing the lamp
in or out of circuit the safety switch being arranged to make contact with the
hand-switch so that the safety switch may be opened and set for action by moving
the hand-switch to throw the lamp into action as hereinafter fully set forth.
In the accompanying Drawing
Figure 1 represents a sectional side elevation of the mechanical portion of an
electric lamp, of a well known type, embodying my present improvements.
Figure 2 is a plan or top view thereof partly in section.
Figure 3 is a sectional elevation shewing the negative binding post on which the
hand-switch is mounted and other parts.
In Figures 1 and 2 a a¹ indicate two circular metallic heads or end pieces which
are rigidly connected by the rod b and standards c c thus forming the frame of the
lamp which frame sustains the mechanism and the whole is inclosed and protected
by the cylindrical case d in the ordinary manner. The upper carbon-holder e slides
centrally through the heads a a¹ and has, a number of rack-teeth upon one side
which engage with teeth upon one of a train of wheels carried in the pivoted
frame f. The said flame is pivoted at its lower outer corner f¹ to the armature
lever and the upper outer corner of the frame is connected with the free end of a
plate-spring which is fixed at its inner end to a post j¹ depending from the upper
head a.
The armature lever i has the form of an open skeleton frame of T-shape
(see Figure 2) placed horizontally and is pivoted between the standards c c on the
trunnion screws c' at a point below the centre of the frame f. The wide end of
the shaped lever lies between the regulating magnet land to this end of the lever
is hung or pivoted the armature m on the trunnion screws m¹. The magnets klare
preferably of the tubular or so called "axial" form and each consists of two coils or
spools in the ordinary manner screwed to the respective heads a a¹ as shown. The
armature is of such form that its two upper horns or poles project up into the
tubular portions of the inagnet k while the two lower poles hang down in the tubular
portions of the lower magnet l. The lower magnet being wound with coarse wire
is of low resistance and it is arranged in direct circuit with the carbons, being thus
the "separating" magnet while the coils of the upper magnet k, are formed of fine
wire as shown, being therefore of high resistance, and this magnet is placed in a
shunt, that is to say the opposite ends of the coils are connected directly to the
positive and negative binding posts o o¹ so that it always offers a path of high
resistance for the flow of the current independent of the carbons and arc, and forms
the "feeding" magnet. The two magnets will thus act in opposite directions on the
armature m, the upper magnet k tending to pull it up, while the lower magnet
tends to pull it down. The action of the shunt magnet k on the armature m is
assisted by the springs n n¹ the tension of the spring n being constant and that of
the spring n adjustable as shewn.
When the lamp is out of circuit, the magnets will be powerless and the springs
n n' will move the armature lever i in a direction to lift the armature in the

page_text: tubular portions of the magnets and depress the short arm of the lever and the
frame thus withdrawing the escape wheel of the train from the stop tooth h on
the spring j. The train of wheels will thus be released, and the carbon-holder will
descend slowly by its own weight till the carbon which it holds touches the lower
carbon. If the lamp is now put in circuit, the current will flow from the positive
binding post o through the metallic frame of the lamp, the carbon holder e and
the upper carbon to the lower one. From the lower carbon the current will flow
by the usual path, not shown in the Drawing, to one end of the coils of the direct
magnet and flowing through the said coils will finally pass off by the negative
insulated post o¹ and thence return to its source. Upon the current thus flowing,
while the carbons are together, the direct magnet will become strongly attractive
and immediately depress the armature m, move the lever i against the stress of the
springs n n and lift the train of gearing and the carbon-holder e bodily, thus
separating the carbons, causing the arc to be formed between them, and finally
bringing the escape wheel against the stop tooth h, thereby holding the carbon in
suspension to maintain the arc.
k
In proportion as the carbons burn away so as to lengthen the space or arc
between them the resistance to the passage of the current through the arc and
direct magnet increases and a greater proportion of current flows through the
shunt magnet which will thus finally become strong enough to overcome, with
the assistance of the springs n n¹. the attraction of the direct magnet 7 and thus
move the parts slightly in the opposite direction, sufficiently to either depress the
carbon-holder bodily or release the train of wheels momentarily so as to give the
necessary down feed to the carbon to shorten the arc or restore it to its normal
length. The magnet thus separates, and the magnet feeds, and the armature
thus floats as it were between the two, so that when the arc is of normal length,
the attraction of the two magnets is equalized, and the armature and the other
connected parts remain stationary, the constant tendency of the above described
mechanism being to keep the arc at its normal length. The normal length may
be one quarter of an inch, according to the nature of the lamps of the generator, or
of the current produced thereby, or other conditions, and this length may be varied"
as required by adjusting the spring n¹ a greater tension of which will produce a
shorter arc, and a less tension a longer one.
When a series of lamps, however, are adjusted, for a certain length of arc which
is found to give the best effect it should be maintained uniformly in all the lamps,
for should any one become abnormally great, it would interfere with the perfect
working of the rest. This abnormal are might occur from some clog in the
mechanism of the lamp or other failure of the carbons to feed, and if the arc
should continue to increase, say for an inch or more, it would as before stated not only
interfere with the other lamps, but might injure the generator and from the intense
heat and flame emitted by the long arc would be likely to cause fires.
My improved cut-off device which is added to the above described mechanism to
prevent these contingencies will be readily understood. In Figures 1 and 2 p
indicates a hand switch by which the lamp may at any time be voluntarily thrown
into or out of circuit. This switch has the usual form of a curved lever made of
metal with non-conducting knob p' on its manipulating end while its opposite end
is mounted on the stem o of the negative binding post o' as shewn in Figure 3,
so as to turn freely thereon, yet always remain in electrical connection with the
negative post. The switch lever as seen in Figure 3, turns on the stem o between
the base of the negative post. and an underlaying washer and the post and
switch are insulated from the metallic lamp head a by the usual insulating piece r.
When the switch is closed, its free end rests upon the metallic boss or seat 8 which .
is in metallic connection with the head a, consequently when the switch is thus
seated or closed, as shown by full lines in Figure 1 and dotted lines in Figure 2
the lamp will be thrown out of circuit as the switch will form a direct free passage
for the current from the positive post o (see Figure 2) through the head a to the
negative post o¹. The lamp will however be instantly thrown into action by

page_text: opening the switch as shewn by full lines in Figure 2, which will cause the
current to take the active path through the magnets and carbon.
The switch lever p is formed with a short arm p" Figure 2, on the end
opposite to the manipulating end, which short arm is formed with a broad flat
contact making face p¹ by bending the edge of the metal plate which forms the
switch-lever and filing the face thus formed. Arranged in relation to this contact-
making face pl is the automatic or safety-cut-out switch t which in both shape
and action is similar to a pistol hammer This hammer or levert of the safety-
switch is formed at its free end with a broad contact making face t¹ to meet with
the face p of the band-switch, and at its other end is formed with a hub which
rests upon the lamp head a and is keyed to a stud u which passes through and
turns freely in the lamp head a. Immediately under the lamp head, a small
trigger or catch arm t¹¹ is keyed to the stud and below this a spring u¹ is fitted on
the end of the stud, with one end fixed to the stud, and the opposite end bearing
against the side of the fixed standard c.
When the safety switch is closed it will make contact with the piece p111 of
the hand-switch as shown by dotted lines in Figure 2, but when opened, it will
be moved away from the hand-switch as shown by full lines and this motion will
deflect the spring u¹ and move the trigger arm t¹ over the hooked end of a trigger
or catch-lever which will thus hold the switch in its open position. This catch
lever vis pivoted just under the head a with its hooked arm projecting in the
path of the trigger 11 while its opposite and operating arm is depressed by a
spring so as to keep the hooked end in constant engagement with the switch as
shewn, and this operating arni of the catch lever projects between the coils or
spools of the shunt-magnet k and its end directly overlies the centre of the cross-
bar of the armature m, as clearly shewn in Figures 1 and 2. A long pin w is
fixed in and rises from the middle of the cross bar of the armature and terminates
just under the operating arm of the catch-lever v. In all the normal movements
of the armature m and armature lever i down or up to regulate the position of the
carbons, the pin w does not touch or affect the trigger lever v.
The armature lever, in its regulating movement plays between the coils or
spools of the magnets kl and its play is limited by pins which project from the
lever toward each spool head. The armature lever may be raised to the limit of
its upward motion to produce the feed of carbon when the stop pin x will strike
the head of the shunt-magnet k yet the tripping pin won the armature will not
touch or affect the trigger lever v although it will closely approach it as seen in
Figure 1. When the armature lever is thus raised to the limit of its upward
motion the carbon-holder should descend freely to give the necessary "feed" to
the carbons. If however the carbon fails to feed, for instance on account of some
derangement of the gearing, or other mechanism, or from any other causes the carbon
points will then continue to burn apart, thus increasing the length and resistance
of the arc and correspondingly increasing the strength of the shunt-magnet k.
The parts are so adjusted that when the arc gets dangerously long, say,
half an inch if the normal length be one quarter of an inch the shunt-
magnet will become sufficiently strong to bodily lift the armature m a slight
distance off the armature lever i or rather off the pivoted points of its
trunnion screws ¹ for in this lamp the armature is capable of a limited upward
play on its trunnion screws by reason of the short downwardly extending slots y
on the sides of the armature in which the pivots of the screws enter.
Whereas
heretofore the trtinnions of the armature have been without play in the armature
lever. This independent upward movement of the armature, after the armature
lever is raised to the limit of its upward motion, will, as may be readily seen on
reference to Figure 1, force the trip pin w against the end of the trigger lever v
thereby moving the lever so as to depress its hooked end and release the safety
switch which will then be instantly moved by its spring u so as to throw the
switch hammer t into firm contact with the face p thereby instantly extinguishing
the lamp and cutting it out of circuit and at the same time establishing a free

page_text: passage for the current to the other lamps in the circuit, for it will be seen on
reference to Figure 2 that when the safety switch is thus closed the current
will flow directly from the positive post o through the head a to the switch lever t
and thence to the negative post and off to the next lamp.
In order that the strength of the shunt-magnet k shall not have to increase to
a very great extent in order to bodily lift the armature m and trip the safety
switch, a part of the weight of the armature is always supported by a spring w
which encircles the pin w and bears at its lower end on a washer which rests on a
bridge fixed to the armature lever and at its upper end bears on a collar wll
adjustably fixed on the pin by a set-serew as shewn. Hence as the tension of this
spring is increased by setting the collar down, the lifting power of the shunt-
magnet will be more assisted and the switch will be tripped by the smaller
departure from the normal arc; whereas if the tension of the spring is reduced by
setting the collar up, the shunt-magnet will be less assisted and a greater length of
are will be formed before the safety switch becomes tripped and closed, hence the
adjustment of the collar w¹ determines the limit in the length of are allowed before
the lamp will be automatically extinguished.
When the defective lamp is thus extinguished and cut out of circuit, the attention
of the attendant will thus be called to the same and on going to examine the lamp
to remedy the defect he should first close the hand switch p as shewn by dotted
lines in Figure 2. This movement of the hand switch by reason of its arm p¹¹
making contact with the hammer t of the safety switch, will automatically move
the hammer into its cocked or open position where it will be immediately engaged
and held ready for its next automatic action if required.
In Figure 2 to illustrate this cocking action the closed position of the hand
switch is shown by dotted lines and the open position of the safety switch by full
lines, and the contact face p111 of the hand switch when moving to set the safety
switch scrapes angularly against the contact face of the safety switch and thus
keeps the surfaces bright and clean to ensure good conduction. When the hand
switch is thus closed it not only opens and cocks the safety switch for future
action, but still keeps the defective lamp out of circuit, so that the attendant can
examine the mechanism of the lamp and adjust it or remedy the defect, without
fear of receiving a shock or of establishing the arc before the lamp is ready for
action. If he finds that the defect is easily remedied without removing the lamp
or sending it to be repaired, or if he finds, for instance, that there is no defect in
the lamp mechanism but its extinguishing was due simply to the breaking of one
of the carbons, he will after correcting the derangement, open the hand switch, as
shewn by full lines in Figure 2, which will throw the lamp again into full luminous
action while the safety switch remains set ready for action if necessary. This open
position of the two switches is shewn by full lines in Figure 1 and as the hand
switch is thus thrown open it will break contact with the safety switch before it
breaks contact with its seat 8, consequently any spark that may be emitted at the
breaking of the switch circuit will not be emitted at the safety switch but at the
seat 8 of the hand switch and will do no injury as the contact surface, here is
large and frequently subjected by the motions of the hand switch to strong friction
which will keep the parts in good condition for contact. It will therefore be seen
that this safety switch mechanism fulfils all the important requirements stated at
the outset, and is simple and efficient in action and complete in its capabilities.
Furthermore, no other magnets or armatures are used to operate the switch devices,
than those usually employed and necessary for the carbon regulating mechanism,
and the safety switch is always set for action by the necessary motions of the
hand-switch.
While I greatly prefer to employ the armature of the regulating shunt-magnet
to operate the safety switch, yet a special shunt-magnet may be employed for the
purposes in combination with my automatic switch releasing devices.
In lieu of a shunt-magnet, operating by an increase of attraction due to increased
length of arc a magnet arranged in the direct circuit, and operating by a decrease

page_text: of attraction due to the same cause might be arranged to operate or release the
safety-switch as the peculiar form of the switch setting and releasing devices are
not confined to any particular kind or arrangement of operating magnet, and
instead of employing a spring u¹ to constantly bend to close the safety switch, an
equivalent may be used, such for instance, as a weight or a magnet.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent and the manner of performing the same I wish it under-
stood that I claim.
First. The combination, in an electric arc lamp, of a safety switch acting when
closed to cut the lamp out of circuit, a spring or equivalent device acting constantly
to close the said switch, a trigger catch or latch acting to hold the said switch
open, and an electro-magnet circuited in such relation with the arc that an abnor-
mal length of are will cause the armature of the said magnet to trip the said
trigger-catch, release the switch and allow it to be closed by the spring and
thereby automatically throw the abnormal lamp out of circuit, substantially as
herein set forth.
Second. The combination, in an electric arc lamp, of an electro-magnet, circuited
.in operative relation with the arc, and a corresponding armature operatively con-
nected with mechanism for regulating the positions of the carbon points, with a
safety switch arranged in operative relation with the said armature, constructed
to be normally open, but acting when closed, to cut the lamp out of circuit, an
operative connection between the said armature and the said switch having an idle
play or movement during the normal feeding movements of the said armature, but
which connection actuates the switch and closes the same when the said armature
moves beyond the limit of its feed motion owing to an abnormal length of the arc,
substantially as herein set forth.
Third. The combination, in an electric arc lamp, of a safety switch normally
open but acting, when closed, to cut the lamp out of circuit, an electro-magnet
circuited in a shunt from the arc circuit, a corresponding armature operatively
connected with mechanism to feed or regulate the position of the carbons, and
having a limited idle play in its connection with the said mechanism, an operative
connection between the said armature and safety switch, whereby the armature
becomes independently moved from the regulating mechanism, when the latter is
moved to its feeding limit by an abnormal attraction of the shunt-magnet due to
abnormal length of the arc, and thereby 'operates the safety switch to throw the
abnormal lamp out of circuit, substantially as herein described.
Fourth. The combination, in an electric lamp, of a hand switch adapted for
voluntarily placing the same in or out of circuit with a safety switch adapted to
be closed automatically by the mechanism of the lamp on the formation of an
abnormal arc the said safety switch being arranged in operative relation with the
said hand switch, whereby the closing and opening of the hand switch automatically
sets the safety switch in its open position, all substantially as herein set forth and
for the purposes specified.
Fifth. The hand switch formed with a contact face on one arm thereof, in com-
bination with a safety switch or hammer provided with means for retaining the
same in open position and arranged when closed to make contact with the said
face, whereby the movement of the hand-switch will move and set the safety switch,
substantially as herein set forth and for the purposes specified.
In witness whereof I the said William Robert Lake have hereunto set my
hand hand and seal this Thirty first day of May in the year of our Lord
one thousand eight hundred and eighty two.