Year: 1897

page_text: Date of Application (in United Kingdom), 30th Oct., 1897
Complete Specification Left, 30th July, 1898-Accepted, 30th Dec., 1893
I, DR. PAUL MERSCH, of No. 4, Avenue Hoche, Paris, in the Republic of France,
do hereby declare the nature of this invention to be as follows:-
This invention relates to are-lamps of an improved construction, the main
distinguishing feature of which is a device enabling the carbons automatically
to move close together, either when the lamp is first set in operation, or in propor-
tion as the carbons wear out; and further, a device for causing the carbons to
recede from each other, and for limiting or adjusting the intermediate space
between them, for the purpose of kindling the lamp.
The improved lamp comprises two fine wire coils or solenoids, the inner tubes
of said solenoids, upon which the wire is wound, extending below the said coils
and serving to guide the lower carbon-holder.
Two plates or cross-pieces connect the ends of the tubes so as to form a complete
frame.
Washers, brazed on to the tubes serve to limit the length of the solenoids, the
upper washers being in contact with the upper cross plate.
The tubes, where they leave the coils, are provided with slots to afford a passage
for each end of the lower carbon-holder. To the ends of the carbon-holder are
fixed cores or plungers, which may be tubular or solid, and of round conical or
square shape in section, and are adapted to slide within the tubes, either under
the magnetic action of the coils, or by their own weight,-plus the weight of the
carbon-holder as will be presently explained.
To the upper end of each of the cores, there is attached a chain, cord or band:
these chains issuing from the tubes through an aperture, formed in the plug
which closes the said tubes, and passing over small pulleys mounted on brackets
connected to the upper cross plate; and the ends of such chains being fastened
te the upper carbon-holder.
The upper carbon-holder, being lighter than the lower carbon-holder, secured
to the cores is guided in its vertical movements hy guide rods, the section of
which may vary at will, and which are fixed to the end washers of the solenoid.
Upon these rols then slide the ends of the upper carbon-holder, which ends are
by their construction fitted for this purpose, being provided with rollers,, or not,
as may be preferred.

page_text: The pulleys, over which pass the chains or cords are provided with cheeks
toothed at their circumference and adapted to operate in conjunction with a
small pawl provided with an elongated aperture and mounted upon a pivot in
the brackets.
As will readily be understood, the pawls prevent the pulleys from revolving
when, in consequence of the chains being drawn by the cores, the lower carbon
holder descends, thereby causing an upward movement of the upper carbon-
holder; for in this case, the chain, by acting upon the pulleys cause them to
perform a rotary movement; but inasmuch as the pawls rest upon the toothed
rims of the cheeks of the said pulleys, they are driven upwards by the teeth of
the cheeks, until the lower end of the oval aperture meets the pivot; at which
juncture the teeth of the pulleys, being in gear with the pawls, lock such pulleys
and also, consequently, the carbons in position, since the chains cannot then
take round the pulleys. But when the said chains move in such a manner as
to move the carbons close together, that is to say, when the upper carbon-holder
descends and the lower carbon-holder rises, the pulleys are free to revolve, as,
in that case, the pawls follow their movement until the upper ends of their aper-
tures meet the pivot, after which they remain in that position, their beaks simply
resting upon (or sweeping) the teeth of the pulleys.
The current reaches the lamp through a binding screw or post, electrically
connected to the upper carbon-holder; after which such current is intended to
flow through the two carbons to the lower carbon-holder, electrically connected
to the metal body of the lamp and to leave the same through the binding post.
The solenoids are arranged in parallel to the main current; to this end their
entrance ends are connected to the inlet binding post and their opposite ends to
the outlet binding post.
The operation of the improved lamp is as follows:
We will suppose that at the time the current is sent into the lamp the carbons
are some distance apart, as, in consequence of this intermediate distance, the
current cannot pass from the upper carbon-holder to the lower carbon-holder it
passes on through the solenoids direct to the outlet binding post.
Under the magnetic action of these solenoids, the cores are attracted upwards
and the lower carbon holder to which these cores are joined, participates in such
upward movement. At the same time as the lower carbon rises, the upper carbon
descends, owing to the connection of the two carbon holders, through the chains.
We have already seen that, when the pulleys revolve for the purpose of bringing
the carbons nearer to each other, the pawls do not hinder their rotary motion:
they simply rest in contact with the teeth of the pulley-cheeks.
The two carbons, on moving in the manner just stated, come into contact with
each other. Inasmuch as, now, the resistance offered by such carbons to the
passage of the current is less than the resistance of the solenoids, the current,
on its way to the outlet binding post passes almost in toto through the upper
carbon-holder, the carbons the lower carbon-holder and the body of the lamp.
As. the current now passing through the solenoids is of very little strength,
the magnetic action of such solenoids upon the cores is discontinued and the
said cores, along with the lower carbon holder which is of greater weight than the
upper carbon-holder, perform a downward movement, which causes a corresponding
upward movement to be accomplished by the upper carbon-holder. But, as has
been explained before, the pawl by its action upon the toothed cheeks of the
pulleys, prevents the carbons from moving apart; for the cores in descending
pull or stretch the chains, which raise the upper carbon-holder in consequence,
and at the same time set in motion the pulleys, which, perform a rotary movement.
But, inasmuch as the pawls are still in gear with the teeth of the checks of the
said pulleys, by reason of the rotary motion of such pulleys they are, in their
turn, pushed upwards until the bottom end of the oval slot meets the pivot. When
this contact takes place, it causes the pulleys, as well as the carbons to stop;
the carbons then standing only just as far apart as is necessary to light the lamp.

page_text: The lamp, therefore, is now in operation, and all the parts forming the regu-
lating device occupy the positions necessary for such operation..
When, in consequence of the carbons wearing away, the distance between them
increases, the resistance of the arc increases likewise, so that a larger amount
of current then passes through the solenoids. This current renders the magnetic
action of the said solenoids more effectual, intensifying it until it is sufficient
to attract the cores upwards. These cores then rise, taking the lower carbon-
holder along with them, and causing the upper holder to descend, through the
intermediate action of the chain; the carbons are consequently moved closer
together. During these movements, the pulleys perform a slight rotary move-
ment, and the pawls which rest upon the teeth of the cheeks of the said pulleys
simply follow this movement until the upper ends of their oval apertures, in
their turn meet the pivot; whereupon they remain stationary in this position,
without exercising any influence upon the operation of the lamp.
The carbons being thus brought together, a less quantity of current now passes
through the solenoids, but, inasmuch as the lamp is now acting as an illuminant,
as has just been explained, it will be understood that the magnetic effect of the
said solenoids must nevertheless be sufficient to prevent any descent of the cores;
since they are constantly being traversed by part of the main current, and seeing
that, as soon as the carbons again move apart, an increased amount of the main
current proportionate to the distance from which the carbons have receded from
each other, will pass through the solenoids, with the effect that they will imme-
diately attract the cores in the upper direction, which will cause the carbons
to move up to each other again, and so on.
In view of the foregoing, it will be understood that the cores and also, conse-
quently the carbon-holders are always, in a manner, kept well balanced.
As the carbons gradually wear off, a steadily increasing amount of main current
will pass through the solenoids, without the illuminative effect of the arc dis-
continuing and this goes on until the magnetic effect of the solenoids becomes
sufficiently powerful to gradually attract the cores; which will accordingly trans-
mit their motion to the carbon-holders so as to bring them nearer together; this
movement of the carbon-holders, towards each other, being in all cases just
sufficient to make up for the wear of the carbons, while it can never move the
carbons into contact with each other, as, the moment no more than the normal
distance between them is left, the current passing through the solenoid must
lack the strength necessary for shifting the cores.
In order that the magnetic action of the solenoids may be the same throughout
their length, .e. with a view to equalizing the magnetic field of the solenoids-
and with the special object of making use of the lamp for continuous currents,
they may be completely surrounded by an iron tube connecting the two washers
of the coils.
As regards the pawls which serve to limit the distance between the carbons
for the purpose of lighting the lamp it is clear that their path might be regulated
by elongating the aperture more or less.
It would be a very easy matter to replace these pawls by any other device capable
of producing the same result. Thus, as will be understood, the bracket might
be provided with a hanger adapted to receive a flat piece corresponding to each
of the pulleys. These parts terminating each in a beak or nose would engage
in the teeth of the said pulleys, and, inasmuch as their vertical path would be
The stroke,
limited by the hangers, they would operate exactly like the pawls.
or extent of motion, of the pieces might be limited by set screws.
The construction of the lamp hereinabove described might also be modified by
making the cores stationary and the coils or solenoids movable. The said cores
would in that case be secured to the cross-pieces and would assume the shape
of inverted truncated cones, the large base of each being attached to the plate:
as to the solenoids, they would be mounted upon tubes, simply surrounding the
fixed cores, and connected by the lower carbon-holder. The cords would be

page_text: fixed to the upper part of the solenoids, would pass over pulleys and be fastened,
by means of hooks or the like, to the upper carbon-holder.
The operation of this lamp would be identical to that of the lamp previously
described, the solenoids in this case doing the duty of the cores.
This method
of operation will be readily understood when it is remembered that a loose
solenoid or coil, mounted upon a core of varying shape in section, tends whenever
a current passes through it, to move in such a manner as to envelop the part of
the core where its sectional area is largest.
Dated this 30th day of October 1897
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
I, DR. PAUL MERSCH, of No. 4, Avenue Hoche, Paris, in the Republic of France,
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:
This invention relates to arc-lamps of an improved construction, the main
distinguishing feature of which is a device enabling the carbons automatically
to move closer together, either when the lamp is first set in operation, or in propor-
tion as the carbons wear out; and further, a device for causing the carbons to
recede from each other, and for limiting or adjusting the intermediate space
between them, for the purpose of striking the are of the lamp.
The invention will be best understood by reference to the accompanying draw-
ings in which
Figure 1 is a vertical elevation of the improved are lamp, partly in section
on line 11, Figure 2;
Figure 2 is a plan or top-view thereof;
Figure 3 is a horizontal section on the line 33, Figure 1;
Figures 4 and 5 are detail views of a portion of the lamp.
Figures 6, 7 and 8 are detail views of a modification of the part represented in
Figures 4 and 5.
Figure 9 represents a series of cores of unequal length, intended for use with
alternating current lamps.
Figure 10 is relative to a lamp the bobbins of which are covered with iron
casing.
Figure 11 relates to a simplified type of lamp having a single bobbin.
The improved lamp comprises two fine wire coils or solenoids A A' the inner
tubes B, B of said solenoids, upon which the wire is wound, extending below
the said coils and serving to guide the lower carbon-holder G, Figure 1.
Two plates or cross-pieces CD connect the ends of the said tubes B B¹ so as to
form a complete frame.
Washers a a¹, brazed on to the tubes B B serve to limit the length of the
solenoids A A', the upper washers, a, being in contact with the plate or cross-
piece C.
The tubes B B¹, where they leave the coils A A', are provided with slots b to
afford a passage for each end of the lower carbon-holder G. To the ends of
the carbon-holder are fixed cores or plungers H H¹, which may be tubular or
solid, and of round, conical or square shape in section, and of a magnetic sub-

page_text: stance such as soft iron (the lower carbon holder G which connects them is also
of iron) adapted to slide within the tubes B B', either under the magnetic action
of the coils A A, or by their own weight,-plus the weight of the carbon-holder G,
as will be presently explained. I would also point out that these tubes BB
might be omitted the cores being guided merely in the bobbins.
To the upper end of each of the cores, H H', there is attached a chain, cord or
band; these chains issuing from the tubes B B' through an aperture j, formed in
the plug which closes the said tubes, and passing over small pulleys K, mounted
on brackets L connected to the upper cross plate C Figures 4 and 5; the ends
of such chains being fastened to the upper carbon-holder G.
The upper carbon-holder G, being lighter than the lower carbon-holder G,
secured to the cores 'H H' is guided in its vertical movements by guide rods M
Figure 1, the section of which may vary at will between V and U, and which
are fixed to the end washers a a of the solenoid. Upon these rods, slide the
ends of the upper carbon-holder (t, said ends being constructed for this purpose,
and provided with rollers, or not, as may be preferred.
The pulleys K, over which pass the chains or cords I are provided with cheeks
toothed at their circumference and adapted to operate in conjunction with a
small pawl ◊ provided with an elongated aperture ò and mounted upon a pivot 7,
in the brackets L.
(see
As will be readily. be seen by reference to Figures 1, 4 and 5 of the drawings,
the pawls prevent the pulleys K from revolving when, in consequence of the
chains I being drawn by the cores H H', the lower carbon holder G descends,
thereby causing an upward movement of the upper carbon-holder G'; for in
this case, the chains or cords I, by acting upon the pulleys K, cause them to
perform a rotary movement; but inasmuch as the pawls O rest upon the toothed
rims of the checks of the said pulleys, they are driven upwards by the teeth of
the cheeks, until the lower end of the oval aperture meets the pivot
Figures 1 and 4): at which juncture the teeth of the pulleys K, being in gear
with the pawls 0, lock such pulleys and also, consequently, the carbons in posi-
tion, since the chains I cannot then rotate the pulleys. But when the said
chains I move in such a manner as to move the carbons close together: that is
when the upper carbon-holder G descends and the lower carbon-holder G
rises, the pulleys K are free to revolve, as, in that case, the pawls O follow their
movement until the upper ends of their apertures o meet the pivot 1, after which
they remain in that position, their noses simply resting upon (or sweeping over)
the teeth of the pulleys K, as shown in Figure 5.
to say,
The current reaches the lamp through a binding screw or post N, electrically
connected to the upper carbon holder G₁; after which such current is intended
to flow through the two carbons to the lower carbon holder G, electrically con-
nected to the metal body of the lamp and to leave the same through the binding
Post N
The solenoids A A¹ are arranged in parallel to the main current: to this end
their entrance-ends are connected to the inlet binding post N and their opposite
ends to the outlet binding post N¹.
The operation of the improved lamp is as follows:
We will suppose that at the time the current is sent into the lamp the carbons
are some distance apart, as, in consequence of this intermediate distance, the
current cannot pass from the upper carbon holder G₁ to the lower carbon-
holder G, it passes on, through the solenoids A A', direct to the outlet binding
post N
Under the magnetic action of these solenoids, the cores H H₁ are attracted
upwards and the lower carhon holder G, to which these cores are joined, partici-
pates in such upward movement. At the same time as the lower carbon rises,
the upper carbon holder G' descends; owing to the connection of the two carbon
holders G G¹ through the chains I. We have already seen that, when the
pulleys K revolve for the purpose of bringing the carbons nearer to each other,

page_text: the pawls do not hinder their rotary motion: they simply rest in contact with
the teeth of the pulley-cheeks (Figure 5).
The two carbons, on moving in the manner just stated, come into contact with
cach other. Inasmuch as, now, the resistance offered by such carbons to the
passage of the current is less than the resistance of the solenoids A A¹, the
current, on its way to the outlet binding post N¹ passes almost in, toto through
the upper carbon holder G', the carbons, the lower carbon-holder G and the
body of the lamp.
As the current now passing through the solenoids A A' is of very little strength,
the magnetic action of such solenoids upon the cores H H is discontinued and
the said cores, along with the lower carbon. holder G, which is of greater weight
than the upper carbon-holder G', perform a downward movement, which causes
a corresponding upward movement to be accomplished by the upper carbon
holder G. But, as has been explained before, the pawl 0, by its action upon
the toothed cheeks of the pulleys K, prevents the carbons from moving apart
except to a limited extent; for the cores H H¹, in descending, pull the chains
or cords I, which raise the upper carbon-holder G¹ in consequence and at the
same time set in motion the pulleys K, which perform a rotary movement in the
direction of the arrows, Figures 1 and 4. But, inasmuch as the pawls are still
in gear with the teeth of the cheeks of the said pulleys, by reason of the rotary
motion of such pulleys they are, in their turn, pushed upwards until the bottom
end of the oval slot o meets the pivot 7. When this contact takes place, it causes
the pulleys K, as well as the carbons, to stop the carbons then standing only
just as far apart as is necessary to form the are and light the lamp.
The lamp, therefore, is now in operation, and all the parts forming the regu-
lating device occupy the positions in which they are represented in Figure 1
of the drawings.
When, in consequence of the wear of the carbons, the distance between them
increases, the resistance of the are increases likewise, so that a larger amount
of current then passes through the solenoids A A'. This current renders the
magnetic action of the said solenoids more effectual, intensifying it until it is
sufficient to attract the cores H H upwards. These cores then rise, taking the
lower carbon-holder G along with them, and causing the upper holder G¹ to
descend, through the action of the chains or cords I; the carbons are consequently
moved closer together. During these movements, the pulleys K perform a slight
rotary movement in the direction of the arrow, Figure 5, and the pawls 0, which
rest upon the teeth of the cheeks of the said pulleys, simply follow this movement
until the upper ends of their oval apertures o, in their turn, meet the pivot 1;
whereupon they remain stationary in this position, without exercising any influ-
ence upon the operation of the lamp.
The carbons being thus brought together, a less quantity of current now passes
through the solenoids A A'; but, inasmuch as the lamp is now acting as has
just been explained, it will be understood that the magnetic effect of the said
solenoids must nevertheless be sufficient to prevent any descent of the cores, since
they are constantly being traversed by part of the main current, and seeing that
as soon as the carbons again move apart, an increased amount of the main
current, proportionate to the distance for which the carbons have receded from
each other, will pass through the solenoids, with the result that they will
immediately attract the cores H H in the upward direction, which will cause
the carbons to move up to each other again, and so on.
From the foregoing, it will be understood that the cores H H and, conse-
quently also the carbon-holders G G are always, in a manner, kept well balanced.
As the carbons gradually wear away, a steadily increasing amount of main
current will pass through the solenoids A A', without extinguishing the are:
and this goes on until the magnetic effect of the solenoids becomes sufficiently
powerful to gradually attract the cores H H which will accordingly transmit
their motion to the carbon-lolders G G¹, so as to bring them nearer together;

page_text: this movement of the carbon-holders, towards each other, being in all cases just
sufficient to make up for the wear of the carbons, while it can never move the
carbons into contact with each other, as, the moment no more than the normal
distance between them is left, the current passing through the solenoid will lack
the strength necessary for shifting the cores H H₁.
In order that the magnetic action of the solenoids A A¹ may be as far as
possible the same throughout their length, i.e. with a view to equalizing the
magnetic field of the solenoids, it is indispensable to completely surround them
with an iron tube connecting the two soft iron washers a a, thereby constituting
a closed magnetic field; these tubes or on casings are slit in the direction of their
length.
On the other hand the arrangement formed by the magnetic cores H H and
the magnetic cross-piece forming the lower carbon-holder G ensures a very remark-
able operation, and one which permits of an invariably equal magnetic action of
the coils upon the cores.
If the cores H H¹ were not connected magnetically, the action of the bobbins
upon the cores would be very irregular because each coil would be provided
with a core with a free external pole, which, as the carbons were consumed, would
draw nearer and nearer to the coil. As the attractive force of the coils constantly
increases the action of this free external pole would be evidenced by working
so much the more irregular that a constant diminution of the weight to be
attracted, owing to the combustion of the carbons, corresponds to the progressive
increase of the attractive force.
The magnetic communication established between the two cores which are
displaced within the coils obviates this defect. By connecting these cores at
their lower extremity by means of an iron cross-piece, an apparatus of horse-shoe
shape is constituted, the free extremities of which pass within the coils.
The presence of a free external pole drawing nearer to the coils during the
working of, the lamp, is constantly avoided: By giving to these pieces of iron
a horse-shoe shape the further advantage is obtained of diminishing, as much as
possible, the magnetic resistance.
As regards the pawls O which serve to limit the distance between the carbons
for the purpose of lighting the lamp, it is clear that their path can be regulated
by elongating the aperture
more or less.
It is obvious that these pawls may be replaced by any other device capable
of producing the same result. Thus, as will be seen by referring to Figures 65,
7 and 8 the bracket L might be provided with a hanger constructed in the
form shown, and adapted to receive a flat piece R corresponding to each of the
pulleys K. These parts R, terminating each in a nose would engage in the
teeth of the said pulleys, and, inasmuch as their vertical path would be limited
by the hangers, they would operate exactly like the pawls 0. The stroke, or
extent of motion, of the pieces being limited by set screws r.
Figure 8 shews an arrangement in which the pawl is very strong and capable
of being readily regulated by means of the screw.
It is extremely advantageous to surround the coils with an iron casing which
serves to diminish the depression of the magnetic forces; this casing is of solid
metal for continuous current lamps. The arrangement is represented in Figure
10; it is also seen in the type of single coil lamp shewn in Figure 11.
In the case of alternating current lamps, the coils are wound with coarser
wire and the casing is formed of sheets of iron insulated one from the other;
the washers and the cross-piece forming the lower carbon holder are likewise of
foliated iron. The cores are replaced by iron tubes in which a slit is formed,
these tubes being filled with iron filings, or a bundle of iron wire may be placed
in them. The regulation is made more regular from one end of the travel to
the other.
In alternating current lamps, the cores H H₁ are of unequal length as shewn
in Figure 9; the shorter core is provided with a non-magnetic prolongation H° for

page_text: ensuring the guiding. This arrangement contributes to an equalisation of the
magnetic action.
In the case of alternating currents, it will be noticed that, from a certain point
in the travel of the cores in the solenoids, the more iron enters the coils, the
less attraction there is, in order to produce a compensation, the length of the
core is reduced upon one side, thereby causing an absolutely equal imagnetic
attraction.
A simplified form of lamp in accordance with my invention is represented in
Figure 11. This lamp comprises a single coil A2 surrounded by an iron casing S:
the core H which is rigidly connected with one of the carbons is provided with
roller and it is guided along the wall of a slit tube 1. It is connected with
the other carbon by means of a cord or chain I' passing over a pulley K¹ provided
with a pawl 01, arranged in a similar manner to those shewn in Figures 6, 7 and 8.
Although I have described in this invention the magnetic yoke connecting
the cover, I would have it clearly understood that I do not claim in this specifica-
tion this specific detail as this forms the subject of another Application for
Letters Patent under No. 19399 and date 12th September 1898.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
In an electrical are lamp provided with one or more solenoids arranged and
adapted with mechanism to operate as herein described, a soft iron case com-
pletely surrounding each solenoid and connecting washers a a¹ with the extremi-
ties of the solenoid with the object of equalizing their magnetic field and forming
a closed magnetic field substantially as described.
Dated this 30th day of July 1898.
HASELTINE, LAKE & Co.,,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.