Improvements in Electric Lamps,
Year: 1899

page_text: Date of Application, 28th June, 1899-Accepted, 29th July, 1899
COMPLETE SPECIFICATION.
Improvements in Electric Lamps,
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by Elihu Thomson,
residing at Swampscott, in the County of Essex, State of Massachusetts, United
States of America, Electrical Engineer) and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:
This invention consists in an improvement in that class of lamps in which the
light-giving conductor is a pyro-electrolyte, or is of such a nature that it is
of low actual or apparent conductivity at ordinary temperatures, and of suffi-
cient conductivity to carry substantial current at higher temperatures, particularly
at the temperature of luminescence.
Such lamps have been known for a considerable time, but very considerable
difficulties have been encountered in causing them to start without the applica-
tion of an external flame and without unduly complex mechanism. The
present improvements aim to overcome this difficulty, and to provide a lamp of
the class described, which shall be self starting, reliable and efficient.
In the drawings annexed to this Specification, Fig. 1 represents a sectional
elevation of a lamp constructed in accordance with the present invention, while
Fig. 2 is an end elevation of the same lamp. Fig. 3 is a modification.
Referring more particularly to Figs. 1 and 2, A is the base or cap, preferably
constructed of metal, and provided with a ring B for attachment to a hook, or
other suitable support. C is a globe, of glass or other transparent or translucant
material, which is screwed into the base A, as shown in Fig. 1. A washer, of
felt or other suitable material, is preferably interposed, as shown at D.
The light-giving body E consists of a cylinder, of porcelain or some other
substance of the class above referred to. As examples of the substances which
may be used in this connection, magnesia, or other oxides of the alkaline earth
metals, or mixtures of such oxides, may be mentioned. The cylinder E is
provided with points E at each end, which points are carried by the screws F, F,
which are preferably formed of platinum or some other highly infusible material.
These screws are adjusted by check nuts F1, F1 in supports G, G, which are
formed of conducting metal, and are fastened by screws to an insulating base H,
which in turn is supported from the cover A. Suitable terminals K, K' are
provided for attachment to the wires of the circuits.
Two carbon blocks or pencils L, L, are attached by metal clips or supports
to the two supporting arms G, G and a third block of carbon, L', is fastened to
a laminated iron core M. This core works with a dash-pot effect in the interior
of a coil of wire N, and a spring O serves to hold the block L' in the position shown
in the drawings, except when current is flowing.
A coil P is so placed as to furnish, when current flows throught it, a field of
force acting upon the gap between the two pencils L, L. The current, supposed

page_text: to enter at the terminal K, flows down the left hand support G, and through the
pencils L, L, L, and the block E in multiple, to the left-hand support G.
Thence it flows through the blow-out coil P and the solenoid N is series, to the
terminal K.
The action of the lamp above referred to is as follows:-When current is first
admitted, the block E is cold, so that no substantial amount of current can flow
therethrough, which results in causing substantially all of the current to pass
through the blocks L, Li, L. At the same time the solenoid N is energized, and the
block N is gradually lifted against the action of the spring O. The dash-pot
action prevents this lifting from taking place too suddenly. This tends to cause
the arc to form between the points L. L, or from the block L to the block L' or
from the block L' to the right-hand block L. The field of force generated by the
coil P is in such a direction as to tend to cause this arc to pass down and to
play upon the block E, substantially enveloping the same in a mass of highly
heated arc vapors.
When the block L¹ has reached its final position, this arc
will either break or be confined to the carbon-blocks L, L. Soon after current is
admitted, the light giving body E will be heated to a point where it will take a
considerable amount of current, which will still further increase the
power of the coil P, SO that the are between the points L, L will
be extinguished if it has not already been extinguished by the movement
of the block L. The lamp will now continue to run without inter-
ruption, unless for some reason the current supply is interrupted. If this occurs,
the block L will again assume the position shown in the drawing, and the
starting action will be repeated. It will be noticed that the arcing points L,
L, L' are formed of carbon or some other suitable material, and are placed in
spring clips T, T, T, in such a way that the arcing points may be taken out
and renewed when they are partially consumed.
A modified form of the invention is shown in Fig. 3. In this figure the
connections are the same, except that the block L' and the starting coil N are
omitted, and in place thereof is substituted a thermostatic device, which as here
shown consists of two strips of metal Q, R, of different co-efficients of expansion.
fastened by insulating supports to the two supporting arms G, G, which carry
the blocks L. L. These supporting arms are in this case pivoted at the
points G2, G3, and the coil P is, as before, connected in series with the
whole lamp.
The action of this form will be readily understood. When current is first
admitted, the two blocks L, L are supposed to be in loose contact, such as to
permit a considerable amount of current to flow if the lamp is on a constant
potential circuit. The result would be to heat the thermostatic device Q, R,
sufficiently to cause the pivoted arms G₁, G¹ to be slightly separated from each
other, forming an arc. This are would be directed by the coil P upon the light-
giving body.E until broken by the wide separation of the points L, L.
If now the temperature of the lamp should fall slightly, on account of the
extinction of the arc, the carbon blocks would still remain separated, though
perhaps not by so great a distance, but if the lamp should actually go out it would
soon cool to such a point that the blocks L, L would again make contact and
establish an arc as before.
In general it is preferable to permit access of air to the lamp, and this may be
accomplished by openings S, S, as shown in Figs. 1 and 2.
The term <
Pyro-electrolytic conductor," as used in this specification and in the
claims, is meant to imply any conductor whatever, which is of very high
resistance at ordinary temperatures, and of sufficiently low resistance to form an
incandescent body at high temperatures.
It will be evident that the lamp above described may be varied to a consider-
able extent without departing from the spirit and scope of this invention, and that
it may be used either on series circuits or multiple-arc circuits, but it is pre-
ferably used on multiple are circuits. Further, it will be evident that, in some

page_text: of its aspects, this invention is applicable to any type of lamp which requires to
be started, whether the conducting body be a pyro-electrolyte or not.
Having now particularly described and ascertained the nature of our said
invention (as communicated to us from abroad) and in what manner the same is
to be performed, we declare that what we claim is:-
1. The combination in an electric lamp, of a pyro-electrolytic conductor,
arcing points in proximity thereto, means for establishing an are for giving
initial heat to the conductor, and means for breaking the are when the conductor
attains the proper temperature.
2. The combination in an electric lamp, of a pyro-electrolytic conductor, means
for establishing an are in proximity thereto, and means for directing the are upon
the conductor.
3. The combination with a pyro-electrolytic conductor, of arcing points in
multiple therewith, means for separating said arcing points, and means for
directing the arc between said points upon the electrolytic conductor.
4. The combination with a pyro-electrolytic conductor, of means for forming
an arc in proximity thereto, and means for creating a magnetic field adapted to
direct the said arc upon said conductor.
5. The combination in an electric lamp, of arcing points and a pyro-electrolytic
conductor in multiple, and a coil in series therewith for directing the are from
said arcing points upon said conductor.
6. The combination in an electric lamp, of arcing points and a pyro-electrolytic
conductor in multiple, a coil in series therewith for directing the arc from
said arcing points upon said conductor, and means for separating said carbon
points when the conductor attains the proper temperature.
7. The combination with a pyro-electrolytic conductor, of renewable arcing
points in proximity thereto.
8. The combination with a non-self-starting electric lamp, of areing points in
proximity thereto for causing or assisting the starting action.
9. The combination with a non-self-starting electric lamp, of arcing, points in
proximity thereto for causing or assisting the starting action, and means for
directing the are from said points upon the lamp.
Dated this 20th day of June 1899.
THE BRITISH THOMSON-HOUSTON CO. LTD.,
W. MARTINDALE,
A. R. MONKS,
Directors,
ALFRED CLEMENTS,
Assistant Secretary.