Improvements in Electric Arc Lamps.
Year: 1897

page_text: Improvements in Electric Arc Lamps.
We, ROOKES EVELYN BELL CROMPTON, of Arc Works, Chelmsford, in the County
of Essex, Engineer, and EDMUND ARTHUR NORMAN POCHIN, of the same place,
Engineer, do hereby declare the nature of this invention to be as follows:--
The invention relates to an improved form of arc lamp in which the arc is
enclosed in a transparent or translucent envelope, so arranged as to greatly retard
the free access of air to the arc: the life of the carbons being thereby prolonged.
In carrying out the invention according to one arrangement a base plate of
iron has clamped to it, preferably on the underside, a disc of asbestos, which serves
to check the transfer of heat from the arc below to the mechanism above, and also
electrically insulates various parts of the lamp from one another.
The striking and feeding mechanism, which in the arrangement under descrip-
tion is supported above the base plate, consists of a pair of solenoids lifting an
inverted horsehoe magnet, and with it a tube, say a vertical brass one in which
latter slides the positive carbon carrier or cartridge. At the bottom end of the
brass tube is the clutch for gripping or feeding the positive carbon according to
the position of the horseshoe magnet. This clutch may be of the tilted washer type,
or other suitable one of the well known forms of clutch.
A dashpot or its equivalent is connected to the horseshoe to prevent violent move-
ment of the parts.
The carbon carrier or cartridge referred to above is according to this invention
of peculiar construction and is formed out of a stout bell mouthed tube provided
with metallic springs or brushes for making contact with the walls of the outer
vertical tube. A slot with notches is formed in the side of the cartridge, and into
this is snapped a piece of clock-spring for gripping the carbon. The slot is of
such a shape that the spring is retained in position by its own elasticity and cannot
be dislodged by the insertion of the carbon; or this retaining mechanism may be
modified so long as the required operation is attained.
For working two or more lamps in series the main coils may be over wound with
a demagnetizing shunt, or an additional shunt solenoid and core may be provided,
which either acts directly on the mechanism or operates a contact breaker and short
circuits a portion of the main winding when the length of arc is too great.
The same solenoid may also be adapted to cut the lamp out of circuit when the
carbons are exhausted.
If desirable, the necessary controlling or substitutional resistances may be
contained within the cover of the lamp.
The upper carbon is fed through a corrugated spherical ended nozzle, and against
the spherical portion fits a washer or cover serving to close the top of the trans-
parent envelope referred to above.
This envelope, which is preferably made of glass, is ground to a flat edge at the
top, and clamped to the lower carbon holder by asbestos washers so as to make an
airtight joint.

page_text: An outer globe or translucent cover is provided to keep rain from the inner
globe or cover and to check the free circulation of air around it.
The inner globe with its carbon holder and the outer globe may all be mounted
on a base plate or platform, and capable of being raised and lowered by the arrange-
ment of slide rods and catches such as is described in the Specification of our
Patent No. 15840, 1892.
The lower carbon holder, to which is clamped the inner globe, is mounted in a
spring socket which secures a firm but yielding joint between the globe and its
cover. In event of excessive pressure occurring within the globe, or translucent
cover, the spring will yield and allow the confined gases to escape between the top
of the globe and its cover, or in an equivalent fashion be relieved.
The outer globe may be mounted in a similar manner or provided with the
necessary relief valves.
The lower carbon holder is capable of being readily removed from its spring
socket to admit of cleaning and trimming.
WM. BROOKES & SON,
55 and 56, Chancery Lane, London, Agents for the Applicants.
We, ROOKES EVELYN BELL CROMPTON, of Arc Works, Chelmsford, in the County
of Essex, Engineer, and EDMUND ARTHUR NORMAN POCHIN, of the same place,
Engineer, 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 an improved form of arc lamp, in which the arc is
enclosed in a transparent or translucent envelope, so arranged as to greatly retard
the free access of air to the are; the life of the carbons being thereby prolonged.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a sectional elevation of an electric arc lamp constructed and arranged
according to our invention.
Figure 2 shews an elevation, Figure 3 a sectional elevation, Figure 4 a horizontal
section (on the line AB of the elevation Fig. 2) and Figure 5 a plan view of the
carbon holder or cartridge.
Figure 6 shews a sectional elevation and Figure 7 a plan view of the spherical
nozzle P and cover R.
Figure 8 shews a sectional elevation and Figure 9 a section (on CD Fig. 8) of
the spring arrangement or device.
In carrying out the invention a base plate of iron E has clamped to it, on the
under side, a disc of asbestos F', which serves to check the transfer of heat from the
arc below to the mechanism above, and also electrically insulates various parts of
the lamp from one another.
The striking and feeding mechanism, which is supported above the base plate,
consists of a pair of solenoids G lifting an inverted horseshoe magnet H and with
it a vertical brass tube in which latter slides the positive carbon carrier or
cartridge.
At the bottom end of the brass tube is the clutch for gripping or feeding the
positive carbon according to the position of the horseshoe magnet. This clutch
may be of the tilted washer, toggle, or any of the other well known types.

page_text: A dash pot is connected to the horse shoe magnet to prevent violent movements
of the parts.
The cartridge N referred to above is of peculiar construction and shown in
detail in Figures 2, 3, 4 and 5. It is formed out of a stout bell mouthed tube,
provided with metallic springs, or brushes, for making electrical contact with the
walls of the vertical tube in which it slides. A slot with notches is formed in the
side of the cartridge, and into this is snapped a piece of clock spring for gripping
the carbon. The slot is of such a shape that the spring is retained in position by
its own elasticity and cannot be dislodged by the insertion of the carbon.
For working two or more lamps in series the main coils may be overwound with
a demagnetizing shunt, or an additional shunt solenoid and core may be provided,
which either acts directly on the mechanism, or operates a contact breaker, and short
circuits a portion of the main winding when the length of the arc is too great.
The shunt winding may also be adapted to cut the lamp out of circuit when the
carbons are exhausted, and also to introduce into the circuit the necessary substi-
tutional resistance to take the place of the lamp when cut out. This substitutional
resistance, and also the necessary steadying resistance, may be contained within
the cover of the lamp.
The upper carbon is fed through a corrugated spherical ended nozzle P, (Figs. 6
and 7) and against the lower spherical portion fits a washer or cover R serving to
close the top of the transparent envelope referred to above.
The spherical shape of the nozzle P enables the cover R to make a gas tight
joint in any position whether the said cover remains truly horizontal, or is tilted
at an angle.
The said envelope, K, which is preferably made of glass, is ground to a flat edge
at the top, and clamped to the lower carbon holder L by asbestos washers, so as
to make an air tight joint.
An outer globe S is provided to keep rain from the inner globe, and to check
the free circulation of air around it.
The inner globe K, with its carhon holder, and the outer globe S, may all be
mounted on a base-plate, or platform and be capable of being raised, or lowered by
the utilization of an arrangement of slide rods and catches as are described in the
Specification of Letters Patent No. 15840 granted to us and dated September 3rd
1892.
To this arrangement of slide rods and catches separately considered we herein
make no claim, but whereas in the said former Specification the arrangement of
slide rods and catches was utilized to effect the opening of the body of the lamp,
and of simultaneously disconnecting it electrically from the circuit; in the present
invention the said arrangement of slide rods and catches is utilized in effecting
the lowering of the globe of the lamp.
By pressing the catches T the globes may be lowered for trimming the lamp till
the said catches engage in the slots M, where they will be securely retained, allow-
ing the free use of both hands.
The lower carbon holder L, to which is clamped the inner globe, is mounted in
a spring socket (Figures 8 and 9) which secures a firm but yielding joint between
the globe and its cover. In the event of excessive pressure within the globe the
spring W will yield and allow the confined gases to escape between the top of the
globe and its cover.
The outer globe may be mounted in a similar manner, or provided with relief
valves.
The lower carbon holder is capable of being readily removed from its spring socket
to admit of cleaning and trimming.
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. The arrangement of an electric arc lamp, substantially as shown and described.

page_text: 2. In an electric arc lamp, the special form of carbon holder, or cartridge, shown
in Figures 2, 3, 4 and 5.
3. In an electric arc lamp, the construction of the spherical nozzle shown in
Figures 6 and 7.
4. In an electric arc lamp the spring arrangement or device shown in Figures 8
and 9 for the purposes described.
5. In an electric arc lamp the combination or arrangement of globe lowering
rods and catches as and for the purposes described.
Dated the 9th day of December 1807
WM. BROOKES & SON,
55 and 56, Chancery Lane, London, Agents for the Applicants.