IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
Year: 1881

page_text: LETTERS PATENT to James Edward Henry Gordon, of 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 17th January'
1881.
JAMES EDWARD HENRY GORDON, of Dorking, in the County of Surrey.
"IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
In the Specification of a former Patent granted to me, No. 1826, in the year 1880,
I described an electric lamp in which light was given by balls of refractory metal
on thin stems heated by the discharge of bigh tension alternating currents
between the balls.
I have found that the working of such a lamp is improved by enclosing the balls
within a glass globe or chamber in which a vacuum is produced. I find it better
that the stems of the two exterior balls, or of the two balls when only two are used,
should be approximately in the same straight line, and project in opposite directions
from the balls. This causes the discharge to take place more completely from the
balls and not from the stems.
I also generally find it better that the residual gas of the vacuum should not
contain oxygen.
-
The balls might also be made of other refractory conducting material.
In case of the glass becoming blackened before the balls are dissipated, some
scouring material, either liquid or solid, may be previously introduced into the globe,
which would clean it when the glass was shaken, or when the materials were
otherwise caused to rub or pass over the inner surface of the globe.

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 15th July 1881.
JAMES EDWARD HENRY GORDON, of Dorking, in the County of Surrey.
"IMPROVEMENTS IN APPARATUS FOR PRODUCING ELECTRIC LIGHT."
In the Specification of a former Patent granted to me, No. 1826, in the year 1880,
I described an electric lamp in which light was given by balls of refractory metal
on thin stems heated by the discharge of high tension alternating currents between
the balls.
I have found that the working of such a lamp is improved by enclosing the balls
within a glass globe or chamber in which a vacuum is produced. I find it better
that the stems of the two exterior balls, or of the two balls when only two are used,
should be approximately in the same straight line, and project in opposite directions
from the balls. This causes the discharge to take place more completely from the
balls and not from the steins.
I also generally find it better that the residual gas of the vacuum should not
contain oxygen.
The balls might also be made of other refractory conducting material.
In the Drawings hereunto annexed I have shewn examples of electric lamps
constructed according to my Invention.
Figures 1 and 2 are side elevations of a lamp formed in a way suitable for lamps
of small size, say, for giving a light of 6 to 10 candles; Figure 3 is a side elevation
of a lamp formed in a way more suitable for lamps of greater illuminating power.
In Figures 1 and 2 A' are the balls of refractory metal on one end of wire
stems A. The opposite ends of the stems are embedded in a rod of glass C. The
rod is formed up over the wires from glass in a soft plastic state, whilst the wires
are held at any required distance apart. A glass stem is formed to project at right
angles from the glass rod C, and is made to terminate in spiral coils, as shown.
The wire stems A are bent in opposite directions so as to bring the balls close to
one another. The sides of the balls opposite to where the wire stems proceed from
them do not meet one another, but the balls are made to overlap, as shewn, so that
when the balls and stems get heated, the distance between the balls shall not be
decreased by the expansion of the stems; D, D, are platinum conducting wires
attached to the ends of the wire stems; E is a glass globe with a broad neck F.
The glass rod C carrying the wire stems A is inserted into the neck F, and the
conducting wires are drawn through perforations on its opposite sides. Afterwards
the neck is contracted above where the wires pass out through it, and is drawn
down to about the size of a quill tube. The wires where they pass out through
the neck are also sealed to the sides of the neck by glass applied around them
outside the neck, just-in the same way as the terminals of a vacuum discharge tube
are commonly sealed. The globe is then exhausted of air and filled with nitrogen
or hydrogen or other inert gas, and the globe again partially exhausted, the fine
tube leading from it is then sealed and its end broken off. It has been found that
the best pressure is for nitrogen a barometer pressure of about 10 inches, that is,
about /, atmosphere, and for hydrogen about 18 inches. If the pressure is to
low the current passes like the discharge in a Geisler tube without heating the
terminals, and if too high, too high a tension has to be used to light the lamp, and
there would also be risk that the gas when heated might burst the globe.
It will be seen from the Drawing that the spiral coil at the end of the stem of
the glass rod C serves to keep the refractory balls A' approximately at a uniform
distance from the sides of the globe, and that the conducting wires D hold them

page_text: suspended at the desired height. The ends of the conducting wires where they
protrude from the neck are bent into rings, as shewn, and with these the contacts
are made.
To form the larger lamp shown at Figure 3 I proceed as follows:-
The globe is first formed with a long neck, as shewn at Figure 4, and with a
contraction at the lower end of the neck. Into the neck is inserted a glass rod C
carrying wire stems A and refractory balls A¹, and having the conducting wires D
attached to the ends of the stems. The rod C is, as in the lamp just described,
formed with a glass stem terminating in coils which fit within the neck. The
lowest coil rests on the contraction at the bottom of the neck, and the balls are
thus suspended at any required height within the globe. The conducting wires are
led through eyes formed on the interior of the glass coils, and are so kept apart
from one another.
A contraction is then formed in the neck; the neck is cut at the contraction and
a quill glass tube G joined on to it, as shewn at Figure 5. Two short lengths of
quill glass tube H are also joined to opposite sides of the neck, as shown at
Figure 6. The conducting wires are drawn up through the small tubes H by
means of a hook lowered through them, and the extremities of the tubes are
softened and sealed. The extremities of the conducting wires D should be bent
into small loops so that they may the more readily be caught and drawn up; the
ends of the wires should also be just tipped with a small bead of glass before they
are put into the neck, otherwise the ends whilst they are being drawn up towards
the tubes H might scratch the interior of the neck, and render it liable to crack
when heated. The tube G which is joined on to the end of the neck I prefer to
bend into a hook form, as shewn at Figure 7, so that the lamp may be suspended
by this hook. Afterwards the globe is exhausted and filled with hydrogen or
nitrogen or other inert gas, as described with reference to the smaller lamp. The
neck should cone outward slightly from the contraction at the lower end
upwards.
If instead of two refractory balls only being used for each lamp other refractory
balls are to be interposed between them, as described in the Specification of the
Patent above mentioned, then the stems of these balls are secured in the glass rod C
just as the stems of the other balls.
Having thus described the nature of my Invention and the manner of performing
the same, I would have it understood that I claim as my improvements in apparatus
for producing electric light,-
First. The construction of an electric lamp of refractory balls in proximity to one
another carried on thin wire stems within a glass globe or chamber in which a
partial vacuum is produced, the residual gas being either hydrogen or nitrogen, or
other inert gas, substantially as described.
Second. The construction of electric lamps, substantially as herein before
described and illustrated in the Drawing annexed.
In witness whereof, I, the said James Edward Henry Gordon, have hereunto
set my hand and seal, this Seventh day of July, in the year of our Lord
One thousand eight hundred and eighty one.
J. E. H. GORDON. (L.S.)