IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT
Year: 1880

page_text: LETTERS PATENT to James Edward Henry Gordon, of Holmwood Cottage,
Dorking, in the County of Surrey, for an Invention of "IMPROVEMENTS IN
APPARATUS FOR PRODUCING ELECTRIC LIGHT."
PROVISIONAL SPECIFICATION left by the said James Edward Henry
Gordon at the Office of the Commissioners of Patents on the 4th May 1880.
JAMES EDWARD HENRY GORDON, of Holmwood Cottage, Dorking, in the County
of Surrey. "IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
This Invention has for its object improvements in electric lighting.
For this purpose I avail myself of a discovery announced by Mr. Spottiswoode
that an induction coil can be excited by a De Meritens or other dynamo-electric
machine giving alternate currents, and that in this case no contact breaker or
primary condenser is required.
To apply this discovery to electric lighting I so modify the secondary terminals
that a light fit for illuminating purposes can be obtained from the secondary
discharge.
I use coils of moderate size and place a number of them on the circuit of
the machine, either in parallel circuit or in series, or in a combination of
the two.
I break the secondary circuit in one or in several places, getting a light at each,
so that all the lights on any one coil are in series. I use terminals of platinum or
other refractory metal, and the general form consists of a lump of platinum
supported on a thin platinumn wire.
These lumps become white hot, and the thin stems prevent the heat being
conducted away.
A mechanical arrangement is adopted which brings the lumps nearly together
(or connects them by a wire or other conductor) when the current is not flowing
in the primary coil, and separates them to a short distance when the current
commences.
The supports of the terminals should be mounted on some soft substance
and the lights enclosed in globes in order to extinguish the noise which otherwise
occurs.
The advantages of the system are that,—
A great number of lights can be worked from one dynamo-electric machine, that
no carbon or anything else is consumed in the lamp, and that the light is perfectly
steady and no clockwork used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Edward Henry Gordon in the Great Seal Patent Office on the
4th November 1880.
JAMES EDWARD HENRY GORDON, of Holmwood Cottage, Dorking, in the County
of Surrey. "IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
This Invention has for its object improvements in apparatus for producing
electric light. For this purpose I construct the lamps of lumps or knobs of
refractory metal fixed on thin stems of the same. Rapidly alternating currents of
high intensity are made to discharge from one lump to another, and the lumps
which are thereby heated glow and give the light.
The thin stems prevent the heat being conducted away too rapidly.
The following form of the lamp has been found to be the most advantageous,
but is not the only useful form :—
Four pear shaped knobs, each carried by a wire stem, are placed in a line near
together, and the two outside ones connected to the conductors supplying the
currents. When the discharge passes the two outer knobs get moderately hot and
the two inner ones very hot.
The two outer knobs may be platinum and the two inner ones irridium or
irridio-platinum alloy.
The size of the knobs varies according to the strength of the current from about
that of a pin's head to that of a small pea.
It is generally advantageous to make all four knobs of irridium, and to make the
two outer ones smaller than the inner ones.
The stems are preferably of platinum or platinum irridium alloy, and I use wires
about 2 to 3 inches long or more and about 06 inch thick, the object being to have
them the thinnest which will be safe from melting.
The distance apart of the knobs when cold should be such that they just do not
touch when expanded by heat.
Although four knobs are commonly used, 2, 3, or more than 4 may be used in
some cases.
The Drawing shows a section of an electric lamp constructed according to my
Invention. A is a glass globe held, as shewn, by screws A' to the underside of a
plate B of glass or porcelain; C is a plate of ebonite carried by brass pillars D
from the plate B; D₁ are nuts screwing on to the pillars D and holding the plates;
D2 is crosshead on the lower end of each pillar; the screws A¹ screw through
these heads; E is an opaque shade by which the plates B and C may be surrounded;
E' are arms fixed to the plate B; by these arms the lamp can be suspended by
chains F, as shown; G are four stems of platinum wire with knobs H of irridium
on their lower ends. The upper ends of the wire stems are fixed to the caps or
solid tops of tubes I which are carried by the ebonite plate C. The two outermost
wire stems are coupled by wires J to the source of the rapidly alternating currents
of electricity. The suspenders can if desired be used as conductors. Through the
sides of each of the tubes I are screwed three adjusting screws; the ends of the
screws bear against the wire stems, and by means of them the knobs at the lower
ends of the stems can be held and retained at any required distance apart from one
another. There are holes K in the plates B and C through which the wire stems G
pass. These holes also serve to admit currents of cool air to the interior of the
globe A; L is a chimney by which heated air can rise up and escape from the
globe.
-
It is found that much greater tension is required to light the lamps, i.c., to
cause the spark to spring between the cold knobs, than to maintain them when
lighted. Now although it is perfectly possible to produce a current of sufficiently

page_text: high tension either by a machine or by an induction coil to light the lamps, yet
it is found that as every increase of tension throws an extra strain on the insulation
it is advantageous to bring the four knobs into contact, or nearly into contact,
before the lamp is lighted, and to separate them after the current has begun to
to pass. This may either be done by hand, by the use of suitable levers, or
automatically by a lever or levers acted on by the passage of the electric current,
or by the heat generated by it or otherwise.
Alternating currents of sufficiently high intensity for being used with the lamp
may be obtained by the use of induction coils, excited by a De Meritens or other
magneto electric or dynamo electric machine giving alternating currents. No
contact breaker or primary condensor is required. The machine should be one
that give rapid and sharp reversals.
A separate induction coil may be used for each lamp, or several lamps can be
placed on one coil as follows:-
(1.) They may be all placed in series.
(2) A better plan is to let each lamp have its own section of the secondary
wire. This latter plan makes all the lamps in a coil nearly independent of each
other.
The lamps may be lighted and extinguished either by a make and break key in
the secondary circuit or by short circuiting the secondary.
Or the lamps may be lighted and extinguished by shunting the primary current
on and off the coil, or on and off several coils at once, with or without the
introduction of a compensating resistance.
To give some idea of the dimensions of the coils I give the details of one which
I have used for one 100 candle light or two 50 candle lights.
The primary consists of a bundle of iron wires 1.3 inch diameter and 18 inches
long. Three layers of insulated wire 08 inch in diameter are wound on it.
The secondary is wound on an insulating tube, and consists of about 3 mile of
wire 0075 inch diameter covered four times with silk. It is wound in 60 discs.
The external diameter of the secondary coil is about 3.5 inches. There are 3
binding screws, one at each end and one in the centre, so that the whole coil can
be used for one lamp or either half separately.
I have given the above details as examples of what may advantageously be
used with an ordinary Rhumkorff coil, but I do not restrict myself to the use of
this class of coil, as many other forms of induction coils might be used.
The manner above described of obtaining alternate currents of sufficiently high
intensity to work the lamp is not the only way in which such currents may be
obtained. They may be obtained, and in many cases more advantageously
obtained, direct from a magneto electric machine, such as is described in the
Specification of a Patent granted to De Meritens, No. 3658, in the year 1878, but
with the coils wound with a sufficient length of very fine wire. Such machines
are now made by Mr. De Meritens. Other magneto electric or dynamo electric
machines can similarly be made to produce currents of sufficiently high intensity.
A separate circuit is commonly used for each lamp, the lamp being connected to
one or more coils of the machine.
1
I consider that the new light has the following special advantages:-
The accidental destruction of any lamp extinguishes that lamp only.
The light is capable of great subdivision.
There is no vacuum and no clockwork.
The light is extremely steady.
What I claim is,-
First. The production of electric light by means of a combined apparatus
consisting of a magneto electric or dynamo electric machine, an induction coil or
coils, and a lamp containing lumps of refractory metal carried on thin stems, and
heated by the discharge in the secondary circuit or circuits, substantially as
described.
Second. The use in combination for the production of electric light, of a magneto

page_text: electric or dynamo electric machine and a lamp containing lumps of refractory
metal carried upon thin stems, substantially as described.
The use in combination for the production of electric light of apparatus yielding
an alternating electric current of high intensity, and with rapid and sharp reversals,
and a lamp containing lumps of refractory metal carried upon thin stems,
substantially as described.
In witness whereof, I, the said James Edward Henry Gordon, have hereunto
set my hand and seal, this Second day of November, in the year of our
Lord One thousand eight hundred and eighty.
J. E. H. GORDON. (L.S.)