IMPROVEMENTS IN ELECTRIC LAMPS
Year: 1881

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
ELECTRIC LAMPS." A communication from abroad by the Société La Force
et la Lumière Société Generale d'Electricité, of Brussells, in the Kingdom of
Belgium.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at
the Office of the Commissioners of Patents on the 14th April 1881.
"
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. 'IMPROVEMENTS IN ELECTRIC LAMPS." A communication from abroad
by the Société La Force et la Lumière Société Generale d'Electricité, of Brussels,
in the Kingdom of Belgium.
This Invention has for its object the production of an electric lamp which shall
give light by incondescence and offer great resistance, without the necessity for the
employment of long and very attenuated conductors, and this object is effected by
the application in the construction of the lamp of the following principles,
videlicet:
-
In the case of an electrical conductor of any material, form, or dimensions, the
effective electrical resistance of the said conductor may be considerably augmented
by dividing it transversely, and this augmentation of the resistance increases in
proportion as the number of divisions or sections is increased, and as the surfaces
of contact traversed by the current in order to pass from one section to another
are less intimately or closely brought or pressed together.
When the divisions are arranged in very close proximity a short and not very
attenuated conductor will be caused to present a considerable amount of effective
resistance, but depending nevertheless on the inate resistance of the substance or
substances of which it is composed, such as graphite retort carbon, agglomerated
carbon, carbon made from wood or paper, or other calcined organic matter, highly
refractory metals, and the like.
This principle may be applied in the construction (first) of lamps giving light by
incondescence, and in which the air is excluded, and secondly, of lamp giving
light by 'incandescence, and either in the open air or in imperfectly closed
vessels.

page_text: No text detected.

page_text: the wires. The light is enclosed by a bell secured to the plate by a screw
joint.
In the case of electric lamps giving light by incandescence and exposed to the air
or contained in imperfectly sealed vessels, the lamps are constructed upon the same
principles as the one hereinbefore described, but suitable provision is made for the
renewal of the material of which the divided conductors are composed.
The divided conductor is formed by the converging extremities of several rods or
pencils (of conducting and refractory materials) pressed together between two
contact points or surfaces, in such a manner that each rod is traversed transversely
at one extremity only by the electric current. Any convenient number of rods,
not less than three, may be employed. The rods may be solid or hollow, and
cylindrical or polygonal, and the conductor may be composed of similar or different
rods both as regards their chemical nature, their form, or their size.
In the case of a divided conductor constructed as hereinbefore described, the
renewal to compensate for wear may be accomplished by two methods, videlicet :-
1st. When the contact pieces are fixed or stationary the rods are pushed up
together or independently towards the interval between, the said contact pieces
being caused to advance as they were away and press their extremities together.
2nd. When the rods are stationary the contact pieces are caused to advance in
such a manner as to compress the extremities of the rods between them, the rods
being in this case provided with a jointed or flexible mount which allows them to
oscillate upon their point of support.
First first of these two arrangements appears preferable, and is employed in the
lamp next hereinafter described.
In this arrangement all the rods, which must not be less than three in number,
converge downwards, for example, towards one point, so as to bring all their
extremities in contact in a row between the two stationary contact pieces, the two
extreme rods only being in contact with the said pieces. Each rod is acted on
independently by suitably guided weights applied at the upper and diverging
extremities of the rods, which are thereby propelled so as to maintain the lower
and converging extremities of the rods in contact, and cause them to exert the
required degree of pressure upon one another.
The carbons are engaged in a slit or narrow opening formed between two plates
made of refractory and insulating material, and bounded at each extremity by the
contact pieces.
This novel method of guiding a number of rods in a common opening presents
important advantages, viz.,-It enables each rod individually to adjust itself, or to
partake of the movements in the direction of the length of the opening that result
from the bending chance deflections or even faults in the construction of the
apparatus, whilst at the same time the rods are strictly guided in a transverse
direction in such a manner that even when extremely fine rods are employed they
cannot slip out of place laterally.
The opening may be straight, or curved, sinuos, or have diverging sides if
required, especially when different sizes or kinds of rods are employed.
The arrangement consisting of two plates forming an opening between them,
which is limited or bounded by the contact pieces, is hereinafter termed the muzzle
of the lamp. The muzzle is connected to the set of guides corresponding to the
propelling weights, the said guides consisting of tubes; for example, by two plates
bolted or screwed to prolongations of the contact pieces.
The rods may all be propelled by one and the same device, viz., a single weight
guided in a tube serving to push all the rods together in the direction of the
muzzle. It is adviseable to insulate the extremities of the rods from each other
where they bear against the propelling weight, in order to avoid unnecessary
deviations or branching off of the current, which would otherwise become extremely
inconvenient as the rods approach the end of their travel.
In this lamp, as in the one next herein before required, the rods require to be
introduced one by one, which is a long and troublesome operation.

page_text: This objection is removed by connecting together a suitable number of rods at
their upper extremity so as to form multiple conductors, which may be introduced
at one operation.
The rods require to be moveable to a certain extent in their common support or
connection in order to allow the points to converge, and the rods must not be in
electrical communication with each other at the said support or connection.
For this purpose the extremities are covered with an insulating varnish or
coating capable of resisting the action of heat, and are then connected together by
means of a wire or metal ribbon crossed between each two consecutive rods. Any
other system of connection may be adopted, such, for example, as a flexible band
of paper cloth, asbestos paper, and the like, to which the extremities of the rods
may be affixed.
When the improved multiple conductor consists of long and fine or attenuated
rods, the latter should be provided at some intermediate part of their length with
one or more supplementary connections of combustible material which will be
destroyed by the heat before reaching the muzzle.
In order to facilitate the introduction of the multiple conductor into the apparatus
from below, the muzzle is made moveable, or one of the contact pieces is jointed or
hinged.
In lieu of the lamps as working downwards by means of a weight resting on the
upper ends of the rods, the direction of the luminous centre may be varied as
required, as well as the direction of motion, and the latter may be obtained by
means of counter weights, coiled, or other springs or hydraulic pressure.
According to another modification of the improved lamp working in the open air
the apparatus comprises two groups, each containing two or more carbons arranged
in two converging slots or openings in a triangular frame, the carbons on the one
side (say, the right hand side) being propelled by an insulated holder by means of
a lever jointed to the upper part of the other side of the frame, whilst the carbons
on the left are propelled by a lever similar to the first, and jointed to the upper
right hand side of the frame.
A helical spring imparts the required motion to both of these levers.
In the case of this apparatus as in those previously hereinbefore described, the
carbons are guided at their lower extremities in a narrow opening bounded by the
contact pieces.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
14th October 1881.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN ELECTRIC LAMPS." A communication from
abroad by the Société La Force et la Lumière Société Générale d'Electricité of
Brussels, in the Kingdom of Belgium.
The said Invention has for its object the production of an electric lamp which
shall give light by incandescence and offer the requiste resistance to the passage of
the current without the necessity for the employment of long and very attenuated
conductors, and this object is effected by means of the improvements hereinafter
described.
It has been ascertained that the amount of heat developed in a unit of time in
an electric lamp by a current of intensity I is proportioned to the value of the
product E, I, the difference of potential between the two binding posts of the lamp
being represented by the factor E.
If the value of E is small, as in the lamps giving light by incandescence known
as Lodyguine's, Roun's, Bouliguine's, or Reynier's, a considerable value must be
attributed to the factor I inder to obtain a product E, I, of the desired quantity.
Now it is known that currents of great intensity require very large conductors
and perfect contacts, whereby the employment of lamps giving light by
incandescence with small effective resistance is rendered extremely costly on long
circuits.
By reducing the sectional area and increasing the length of the incandescent
conductors (of carbon or highly refractory metals) as is done by some electricians, a
considerable amount of resistance is certainly obtained, but the surface of emission
is at the same time extended; the temperature in proportion-to the work done is
much less elevated and the yield of light less effective.
In the case of an electrical conductor composed of any suitable materials, form,
or dimensions, the effective electrical resistance of the said conductor may be
considerably augmented by dividing it transversely, and this augmentation of the
resistance is directly in proportion to the number of divisions or sections, and
inversely in proportion to the-force with which the surfaces of contact traversed
by the current in order to pass from one section to another are pressed together.
When the divisions are arranged in very close proximity a short and not very
attenuated conductor will be caused to present a considerable amount of effective
resistance, but depending nevertheless on the innate resistance of the substance or
substances of which it is composed, such as graphite, retort carbon, agglomerated
carbon, carbon made from wood or paper, or other calcined organic matter, highly
refractory metals, and the like.
This principle may be applied in the construction (first), of lamps giving light by
incandescence and in which the air is excluded; and (secondly), of lamps giving
light by incandescence, and working either in the open air or in imperfectly closed
vessels.
And in order that the said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawing, the same letters of reference
indicating corresponding parts in all the corresponding Figures.
Figure 1 of the accompanying Drawings is an elevation; and Figure 2 is a
corresponding longitudinal section of a divided incandescent conductor, constructed

page_text: according to the said Invention, and adapted for use in a lamp from which the air
is excluded.
Figures 3 to 12 illustrate modifications of the conductor, illustrated in Figures 1
and 2.
Figure 13 represents a vertical section of an improved lamp for producing light
by incandescence by means of a divided conductor from which the air is excluded;
and Figure 14 is a vertical section of a modification of the lamp, illustrated in
Figure 13.
Figures 15 and 16 illustrate the arrangement of divided on multiple conductors,
adapted for use in lamps to which the air is freely admitted or imperfectly excluded,
and Figures 17 to 22 illustrate various modes of arranging and working the
improved conductors in such lamps as hereinafter more fully described.
In the case of lamps giving light by incandescence and from which the air is
excluded, the luminous organ being in this instance capable of indefinite duration,
there is no necessity to provide for its incessant renewal, and the division of the
conductor is thus enabled to be effected with great facility and simplicity.
Referring to Figures 1 and 2 of the Drawings, a is an incandescent conductor
divided into a number of sections 8, arranged between two supports or contact
pieces A and B, which are caused to exert a certain amount of pressure on the
divided conductor a. This pressure should not be so great as to crush the sections s,
nor so slight as to allow them to separate in such a manner as to admit of a
solution of continuity, which would have the effect of either extinguishing the lamp
or of producing voltaic arcs.
The conductor a is composed of a substance or substances of a highly refractory
nature, such, for example, as graphite, retort carbon, artificial agglomerated carbon,
carbon made from wood, paper, or other calcined organic matter or metals, which
are the most difficult of fusion, such as iridium, osmium, ruthenium, and the like
The contact pieces A and B are either made of the same materials as the divided
conductor a, or of a material of a less refractory nature, such, for example, as
platinum.
It is evident that the divided conductors may be obtained by manufacturing or
cutting out each section separately, and afterwards placing such sections together
side by side, or by taking a conductor made in one piece and cutting it up or
dividing it into the required number of sections. The divided conductor may be
homogeneous or heterogeneous in its composition, and the transverse divisions may
be arranged equidistantly or otherwise. The said divisions in the conductor may
be at right angles to the general direction of the current, as shown in Figures 1
and 2, or oblique to this direction, as shown in Figure 3; or they may be arranged
at different angles in the same conductor so as not to be parallel to one another, as
in the modification, Figure 4, but in no case can they be parallel to the direction of
the current.
The conductors may be of prismatic, polygonal, or cylindrical form in transverse
section and either hollow or solid, and they may be expanded near the centre, as
shewn in Figure 5, or contracted at this part, as in Figure 6, or conical or taper, as
in Figure 7, or of any other special form that may prove desirable in practice.
The surfaces of contact between the sections may be plane as in the arrangement
illustrated in Figures 1 to 7, or they may be curved, angular, plano, convex, or
bi convex, as shewn in Figures 8, 9, 10, and 11 respectively. The two last mentioned
forms of contact surfaces present under equal pressure a more considerable effective
resistance than those preceding, in which the forms of the adjacent surfaces nearly
correspond. The conductor may be bent or curved, as illustrated in Figure 12, or
be of any other suitable sinuous or irregular shape. It is evident that all these
conductors are also capable of working in any position.
Figure 13 shews a lamp having the divided conductor a applied thereto, the
same being fixed between two contact pieces or supports A and B. The support B
is secured to the centre of a metal plate X, and the support A presses the

page_text: conductor a against the support B, being acted on by a spring R and guided in a
tube or socket w formed on a corresponding plate Y. The sealed chamber of the
lamp is formed by a cylinder V of diaphanous and insulating materials, the ends
of the cylinder being closed by being tightly pressed between the two plates
X and Y, which are connected together for this purpose by means of several
suitably insulated screwed bolts Z. The two wires leading from the source of
electricity are connected either directly or indirectly with the two plates X and Y,
which in turn communicate respectively with the two contact pieces or supports
A and B.
The interior of the chamber is deprived of oxygen either by causing combustion
to take place within it or by producing a vacuum by means of a valve communi-
cating with a pump, not shown in the Drawing.
According to another arrangement illustrated in Figure 14 the contact pieces or
supports A and B are respectively fixed to the extremities of two flexible blades
R and S acting as spring, which cause the required pressure to be exerted upon
the divided conductor a between the said supports, the tension of the springs being
adjustable by means of an insulated cross bar Z and a set screw Z¹.
The springs R' and S form continuations of two rods R¹, S', suitably insulated
and passed through a metal plate X, the said rods being also provided with
suitable binding screws for connecting the conducting wires. The light is enclosed
by a transparent bell V secured to the plate X by a screwed collar X¹.
In the case of electric lamps giving light by incandescence, and in which the
incandescent conductor is exposed to the air or contained in an imperfectly sealed
globe or chamber the lamps are constructed upon the same principles as the one
described, but suitable provision is made for the proper renewal of the material of
which the divided conductors are composed.
In the arrangement illustrated in Figures 15 and 16 the divided conductor a is
formed by the converging extremities of several rods or pencils c (of suitable
conducting and refractory materials) pressed together between two contact joints
or supports A and B in such a manner that each rod is traversed transversely at
one extremity only by the electric current. Any convenient number of rods not
less than three may be employed.
The rods c are represented in the Drawing as being solid and cylindrical, but
they may be hollow and polygonal if preferred, and the conductor a may be
composed of a series of similar or different rods both as regards their chemical
nature, their form, or their size.
In the case of a divided conductor constructed as herein before described, the
renewal to compensate for wear may be accomplished by two methods, videlicet:-
First. When the supports or contact pieces A and B are fixed or stationary, as
shewn in Figure 15, the rods c are pushed forwards together or independently
towards the interval between the said contact pieces being caused to advance in
proportion as they wear away and press their extremities together in the same
manner as the stones of an arch, in which the contact pieces may be regarded as
the springers.
Second. When the rods c are stationary the contact pieces A and B are caused to
advance in such a manner as to compress the extremities of the rods c between
them. The rods being in this case provided with a jointed or flexible support at O,
which allows them to partake of the requisite lateral motion.
The first of these two arrangements appears preferable, and is employed in the
lamp next hereinafter described with reference to Figures 17 and 18, which
represent respectively an elevation partly in section, and a corresponding vertical
section of the lamp of this arrangement. The rods c which should not be less than
three in number, converge downwards, for example, towards one point, so as to
bring all their extremities in contact in a row between the two stationary contact
pieces or supports A and B, the two extreme rods only being in contact with the
said supports. Each rod is acted on independently by weights p guided in a tube p',

page_text: and applied at the upper and diverging extremities of the rods which are thereby
caused to advance in such a manner as to maintain all the lower and converging
extremities of the rods in contact, and cause them to exert the required degree of
pressure upon one another.
The carbons are engaged in a narrow opening which is formed between two
plates G, G, of refractory and insulating or nonconducting materials, and is bounded
at each extremity by the contact pieces A and B.
This novel method of guiding a number of rods in a common opening presents
important advantages, videlicet, it enables each rod individually to adjust itself,
or to partake automatically of the movements in the direction of the length of the
opening that are rendered necessary by the bending or accidental deflections of the
rods or other faults or irregularities in the construction of the apparatus, whilst at
the same time the rods are strictly guided in a transverse direction in such a
manner that even when extremely fine rods are employed they cannot slip out of
place laterally.
The
The opening between the plates G in lieu of being straight, as in the example
illustrated in the Drawing, may be curved, sinuous, or have diverging sides if
required, especially when different kinds or sizes of rods are employed.
arrangement consisting of two plates forming an opening between them, which is
limited or bounded by the contact pieces, is hereinafter-termed the muzzle of the
lamp.
The muzzle is connected to the set of guides corresponding to the propelling
weights (the said guides consisting of the tubes p' in the example illustrated) by
two plates S bolted or screwed to prolongations of the contact pieces A, B.
The rods may all be propelled by one and the same device, as shewn in Figure 19,
a single weight P guided in a tube T serving to push all the rods simultaneously in
the direction of the muzzle. It is advisable to insulate the extremities of the rods c
from each other where they bear against the propelling weight, in order to avoid
unnecessary deviations or branching off of the current, which would otherwise
become extremely inconvenient as the rods approach the end of their travel.
In this lamp, as in the one last bereinbefore described, the rods require to be
introduced one by one, which is a long and difficult operation.
This objection is removed by connecting together a suitable number of rods at
their upper extremities, as shown in Figures 20 and 21, so as to form a multiple
conductor which may be introduced into the lamp at one operation.
The rods c require to be moveable to a certain extent in their common support or
connection, in order to allow the points to converge, and the rods should not be in
electrical communication with each other at the said support or connection.
For this purpose the diverging extremities are covered with an insulating varnish
or coating capable of resisting the action of heat, and are then connected together
by means of a wire or metal ribbon c¹ crossed between the rods as shown. Any
other suitable method of connection may be adopted, such for example as a flexible
band of paper, cloth, asbestos, paper, and the like attached to the extremities of the
rods. It is not necessary that the connection should be capable of resisting a very
elevated temperature, as in the event of its consumption or fusion before the rods
are entirely consumed; the latter are not liable to be disturbed thereby, and the
action of the lamp is not affected.
When the improved multiple conductor consists of long and fine or attenuated
rods the latter should be provided at some intermediate part of their length with
one or more supplementary connections or supports of combustible material, which
will be destroyed by the heat before reaching the muzzle.
In order to facilitate the introduction of the improved conductor into the
apparatus from below the contact pieces or supports A, B, may be so arranged as
to be capable of being readily withdrawn or removed or one of the contact pieces
may be jointed or hinged.
In the arrangement hereinbefore described, with reference to Figures 17 and 19,

page_text: the rods c are propelled downwards by means of the weights p, or weight P resting
on the upper ends of the rods; the direction of the luminous centre may however
be varied as required as well as the direction of motion of the rods, and this
motion may be produced by means of counterweights coiled or other springs or by
hydraulic pressure.
Another modification of the improved lamp, in which the conductor is exposed
to the air, is illustrated in Figure 22 of the Drawings.
In this case the rods c are divided into two groups, each group including two
or more rods arranged in converging slots or openings in a triangular frame M, the
rods or carbons on the right hand side being propelled by an insulated holder G
by means of a lever L, jointed at 7 to the upper part of the other side of the frame.
The carbons on the left are arranged in a similar manner, being propelled by a
lever L¹, jointed at to the upper right hand side of the frame M and a helical
spring R connected to the prolongations of the levers L, L', imparts the required
motion to both of these lovers.
In the case of this apparatus, as in those previously hereinbefore described, the
carbons are guided ato their lower extremities in a narrow opening between the
two contact pieces A and B.
It is obvious that the multiple or transversely divided conductors may be
employed in electric lamps, differing in the details of their construction from those
herein before described.
Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and
original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent is,--
First. The employment in electric lamps in which the light is contained in a
closed chamber of conductors divided transversely to the direction of the electric
current, the various parts of the conductor thus divided being pressed together
by the pressure of the end or extreme carbons and presenting multiple surfaces of
contact for the purpose of increasing the effective electrical resistance of the
conductors, substantially as hereinbefore described.
Secondly. The employment in electric lamps producing light by incandescence
of multiple conductors exposed to the air or contained in an imperfectly sealed
chamber, the said conductors being formed by a number of rods, the converging
extremities of which pressed together between two contact pieces receive the
current in a transverse direction, substantially as hereinbefore described and
illustrated in the accompanying Drawings.
Thirdly. The improved arrangement, hereinbefore described, for guiding the
extremities of a number of rods in a common slit or opening bounded at each
extremity by contact pieces, the said arrangement enabling each rod to adjust
itself automatically and move independently in the direction of the length of the
slit in order to compensate for any deflection or other irregularity in the form of
the rods without becoming displaced laterally, substantially as hereinbefore
described and illustrated in the accompanying Drawings.
Fourthly. The improved multiple conductors composed of a number of cylindrical
or polygonal solid or hollow rods of the same or of different form, the diverging
extremities of the said rods being connected together at the proper distance apart
by a flexible connection, which allows the opposite extremities to converge until
they come in contact, and the said multiple conductors being intended for lamps
in which the light is exposed to the air or contained in imperfectly sealed vessels,
substantially as hereinbefore described and illustrated in Figures 20 and 21 of the
accompanying Drawings.
Fifthly. The general arrangements and combinations of parts constituting
electric lamps, substantially as herein before described and illustrated in Figures 1
to 21 of the Drawings.

page_text: Sixthly. The peculiar construction of electric lamps, substantially as hereinbefore
described with reference to Figure 22 of the Drawings.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and seal, the Fourteenth day of October, One
thousand eight hundred and eighty one.
J. HENRY JOHNSON. (L.S.)