Year: 1886

page_text: We, LEGH SYLVESTER POWELL and ROBERT PERCY SELLON both of 112 Belvedere
Road Lambeth in the County of Surrey Electricians do hereby declare the nature
of this Invention to be as follows:-
This Invention is intended to permit the manufacture of Incandescent lamps so
that a far more uniform amount of light may be obtained in the lamps under con-
stant conditions of electro motive force or current than has been obtained by any
other process.
Up to the present attempts have been made to obtain such a result by using
filaments of equal surface by making them of equal length and guage through-
out and together with that condition to make them with an equal uniformity of
resistance.
It has been found difficult to make filaments which have a uniform area of surface
with reference to their length.
It has been found equally difficult to make filaments which being of the same
length, have a uniform resistance when in a state of incandescence.
The object of this invention is to obtain such an approximation of equilibrium
between the area of surface of a filament of an incandescent lamp, and its electrical
resistance when in a state of incandescence as to insure practical uniformity of
incandescence in lamps manufactured by its means. We take the filament whose
resistance with reference to the area of its surface, has to be measured and arrange
by suitable means to vary to any desired extent the length of filament through
which the current, used to incandesce it, shall pass until the required degree of
incandescence is attained, the filament being subjected to a constant electrical
pressure.
A temperature which shews a bright red heat is a very suitable one.
For the purpose of arriving at the degree of incandescence required a visual
standard such as an incandescent lamp maintained at a constant temperature may
be conveniently used. During the above operation any gas or vapour which would
injure the filament is excluded.
Whilst not limiting ourselves to any particular arrangement of apparatus
for carrying this Invention into effect the following is given as an instance of
one means for attaining the desired end viz-We provide two vessels containing

page_text: mercury insulated from one another into each of which one end of the filament is
immersed. The level of the mercury in the vessels or the depth of immersion of
the ends of the filament in it, can be varied by suitable devices, so that the length
of that portion of the filaments which is not immersed in the mercury can be varied
at will. By trials we by this means arrive at a length of filament, not so immersed,
which shews the required state of incandescence.
This length of filament may be marked by any suitable means, for example if the
contacts be made by mercury as above described it may be caused to discolour the
filament.
We mount the filament on or attach it to its support with reference to these
marks.
By means of this Invention any material capable of being used as a filament for
an incandescence lamp may be adjusted without the usual process of incandescence
in a hydrocarbon or similar gas.
J. HENRY JOHNSON,
Agent for Legh Sylvester Powell
and Robert Percy Sellon.

page_text: We, LEGH SYLVESTER POWELL and ROBERT PERCY SELLON both of 112 Belvedere
Road Lambeth in the County of Surrey, Electricians 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 is intended to permit the manufacture of Incandescent Lamps so
that a more uniform amount of light may be obtained in the lamps under constant
conditions of electro motive force or current than has been obtained by any other
process.
It has also for its object to facilitate the manufacture of such lamps.
Up to the present attempts have been made to obtain such a result by using
filaments of equal surface by making them of equal length and guage throughout
and together with that condition, to make them with an equal uniformity of
resistance.
It has been found difficult to make filaments which have a uniform area of
surface with reference to their length.
It has been found equally difficult to make filaments which being of the same
length have a uniform resistance when in a state of incandescence.
The object of this Invention is to obtain such an approximation of equilibrium
between the area of surface of a filament of an incandescent lamp and its electrical
resistance when in a state of incandescence as to ensure practical uniformity of
incandescence in lamps manufactured by its means. And we are enabled to
measure and determine in each individual filament the point where the equilibrium
above referred to exists.
We effect this by taking the filament whose resistance with reference to the area
of its surface has to be measured and while subjecting it to a constant electrical
pressure arrange by suitable means to vary to any desired extent the length of
filament through which the current used to incandesce it shall pass until the
required degree of incandescence is attained.
A temperature which shews a bright red heat is a very suitable one.
For the purpose of arriving at the degree of incandescence required a visual
standard such as an incandescent lamp maintained at a constant temperature may
be conveniently used-During the above operation any gas or vapour which would
injure the filament is excluded:-for example the operation may be conducted in
vacuo or in hydrocarbon gas, supplied to the vessel in which the operation is
conducted at atmospheric pressure or otherwise.
Whilst not limiting ourselves to any particular arrangement of apparatus for
carrying this Invention into effect we will describe with reference to the accom-
panying drawings means which we find suitable for attaining the desired end.
Figure 1 is a sectional view of one arrangement-Two vessels A B are provided
containing mercury and insulated from one another and into each of these vessels one
end of the filament C to be tested or adjusted is immersed the said filament being

page_text: held on holders or clips D which are secured in a closure or stopper E and form the
conductors for the current to and from the filament C. The said vessels A and B
are enclosed in a transparent vessel F their lower open ends passing through the
said vessel F and being there connected to flexible tubes a and b which have at
their other ends a² 63 containers of mercury, the said containers being supported
on a carrier G, which can be raised and lowered by the winch H so that the level
of the mercury in the vessels A and B, and consequently the depth of immersion of
the ends of the filament C, in it can be varied by raising or lowering the con-
tainers a² 6 so that the length of that portion of the filament which is not
immersed in the mercury can be varied at will. The interior of the vessel F is to
be kept free of any air or gas which would injure the filament during treatment.
This may be effected by circulating an inert gas through the vessel during the
operation. By trials we by this means arrive at a length of filament not so
immersed, which shews the required state of incandescence.
This length of filament may be marked by any suitable means, for example, if
the contacts be made by mercury as above described it may be caused to discolour
the filament or adjustable mechanical devices may be made to indicate the length
as above.
We mount the filament on or attach it to its support with reference to these
marks. Figure 2 shews a modification of the means for adjusting the level of the
mercury in the vessels A. B. wherein in place of altering the position of the con-
tainers a b² the level of the mercury therein is altered by means of plungers i
connected to racks with which engage pinions ; by rotating which the plungers
in the containers a² 62 press on the mercury and displace it more or less and so
alter the level of the mercury in vessels A and B. Figure 3 shews a modification
wherein the vessels A and B are themselves raised and lowered by means of a
screw engaging in a nut in the support of the said vessels. The same Figure
shews another modification wherein the clips or holders D are adjustable by means
of racks & thereon with which engage pinions m by which the clips or holders, and
with them the filament C can be raised and lowered as desired. Of course the
vessel F is made air tight. f. f in figures 1 and 3 are the inlet and outlet for the
circulation of a non injurious gas through the vessel F.
By means of this Invention, any material, capable of being used as a filament for
an incandescence lamp, may be adjusted without the usual process of incandescence
in a hydrocarbon or similar gas for the purpose of altering its resistance.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is
In the manufacture of incandescence Electric Lamps subjecting the carbons or
filaments or portions to be rendered incandescent in use to the treatment herein-
before described, that is to say, to variation of the length while raised to
incandescence and subjected to a constant electrical pressure for the purpose and
by the means substantially as hereinbefore described also the mechanical arrange-
ments for the purpose herein before described and illustrated in the accompanying
Drawings under several modifications.
ليوم