IMPROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY, AND AN APPARATUS FOR ITS APPLICATION TO ILLUMINATING PURPOSES
Year: 1878

page_text: LETTERS PATENT to John Edwards Stokes, of Eastcott Villa, Selwyn Road,
Upton Manor, in the County of Essex, for the Invention of "IMPROVEMENTS IN
OBTAINING LIGHT BY ELECTRICITY, AND AN APPARATUS FOR ITS APPLICATION
TO ILLUMINATING PURPOSES."
Sealed the 28th December 1878, and dated the 25th October 1878.
PROVISIONAL SPECIFICATION left by the said John Edwards Stokes at the
Office of the Commissioners of Patents on the 25th October 1878.
JOHN EDWARDS STOKES, of Eastcott Villa, Selwyn Road, Upton Manor, in the
County of Essex. "IMPROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY, AND
AN APPARATUS FOR ITS APPLICATION TO ILLUMINATING PURPOSES."
From a battery or magneto machine which produces the electricity I pass the
current of electricity to an apparatus, where I attach the conducting wire to a
binding post, which is insulated; and from here the current goes through a post to
which is attached the end of a coil of platinum or iridium wire, or their metallic.
equivalent, and the other end of the coil is attached to a post through which the
current passes, and then to a binding post, from whence it is conducted back to the
battery or magneto machine, thus completing the electric circuit. The coil referred
to is a very fine wire, not larger than a sewing thread, and it offers sufficient
resistance to the current to create an incandescent heat, which produces a brilliant
light. I surround this coil with a single or preferably a double glass case having a
space between of about a half inch, which is filled with alum or its equivalent for
the purpose of retaining the heat and thus reducing the amount of electricity to be
used. At the end of this glass case there is a metal top or cover to which is
attached a wire of platinum, iridium, or their equivalent, which wire passes
Price 6d1

page_text: through the coil and is connected to a lever, which lever acts to the point of an
adjustable screw. Whenever this wire, which is connected to the metal top and
the lever, becomes sufficiently hot it will expand and force the lever to the point of
the screw, thereby forming a short circuit and relieving the coil from getting to a
melting heat. By this I secure an imperishable result as to the material employed,
as also an unbroken, constant, and steady light. The apparatus employed is barely two
inches in size, and can be fastened to an ordinary gas burner by means of a screw.
By the connection between the lever and the metal top of the glass case, whereby
the short circuit is formed, I am enabled to protect and relieve the coil from
destruction, as also thereby regulating the constant supply of light. By the coil I
create a quantity of illumination indispensable to success, and not attainable here-
-tofore-by-the-use-of-similar-substances..

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Edwards Stokes in the Great Seal Patent Office on the 25th
April 1879.
JOHN EDWARDS STOKES, of Eastcott Villa, Selwyn Road, Upton Manor, in the
County of Essex. "IMPROVEMENTS IN OBTAINING LIGHT BY ELECTRICITY, AND
AN APPARATUS FOR ITS APPLICATION TO ILLUMINATING PURPOSES."
First. This Invention relates to a manner of producing an incandescent light from
metal by electricity.
Second. It relates to the use of expansion of metal in an apparatus which is
arranged to govern the current of electricity producing the light, and this apparatus
is so designed that it controls the current in such manner that a steady and uniform
brilliancy will be maintained so long as the electric current in proper force is
provided.
Light from such incandescence is not new, and I therefore do not presume to an
originality in this respect, but my means of regulating the current so that the
metal producing the light will be preserved from melting is new, novel, and
useful.
Figure 1 is a front view; Figure 2 is a side view; Figure 3 is a back view;
Figure 4 is another view of modified form, and which shows a double glass sur-
rounding the light, and also a modification of the lever and screw to that shown in
Figure 1. These forms of adjustment are all applicable each to the other.
That the different parts may be known I have given views of several portions of
the apparatus, and will give the names in numerical order.
1 is a piece which holds the expansion or regulating wire; 2 is a sleeve which
clamps the same; 3 is a metal top, or it may be made of other suitable material;
4 is a sleeve which clamps the regulating rod into piece 1; 5 is the expansion or
regulating rod; 6, 61, are sleeves which clamp the ends of the coil A; 7, 71, are posts
which support the illuminating coil A; 8 is a ring which secures the glass globe
or tube 17; 9 and 9, 91, represent levers which in connection with the adjustable
screws 11 and c and d form conductors by which a short and free circuit is esta-
blished whenever the regulating wire 5 expands so that they may connect; 10 is an
angle piece for holding the adjustable screws 11 and c and d; 12 is an angle piece
for holding the regulating lever; 13 is a spring to produce tension, so that the
regulating rod will not kink;.also e is a spring to safety lever 91, to hold it to
regulating lever 9, and also to produce tension on rod 5; 14 is the base piece made
of some non-conducting material; 15 is a screw for holding the lamp to a gas
burner or supporting stand; 16 represents gas tube with burner; 17 is a glass tube
or globe enclosing the whole illuminating part. Sometimes a double glass is used,
as shown in Figure 4, and having a space between, which may be filled with alum
or a non-conducting substance, to prevent radiation of heat, or the space may
remain for air space alone. 18, 18¹, are two binding posts for attaching the main
conductors.
In Figure 4 the levers 9, 91, have a conductor to post 71 and to binding post 18',
also post 7 and angle piece 10 and binding post 18. In Figure 1 the lever 9, the
angle piece 12, the post 7, and binding post 18' are connected by a conductor, also
post 7, angle piece 10, and binding post 18.
The operation of the apparatus is as follows:-From the electrical machine the
current goes to the binding post 18¹, thence to the post 71, thence through the coil
of platinum or irridium wire A, where the resistance creates the incandescence, and
thence it passes by the post 7 to the binding post 18, and back to complete its circuit.
It follows that unless some relief came to the coil A the intensity of the current
would cause it to melt. I have therefore provided the regulating rod 5, which,
being within the centre of the coil A, necessarily receives the greatest amount of
heat in advance of the coil, and consequently expands so as to cause the lever 9 to

page_text: come in contact with the screw 11, which has been properly adjusted, so as to
relieve the coil from reaching a melting heat, because when the contact takes place
the current of electricity is diverted from the coil, and makes a short circuit by way,
of the binding post 18¹, angle piece 12, lever 9, screw 11, angle piece 10, and'
-binding post 18, thus completing the circuit. The change of current from the coil
serves to reduce the heat, and in consequence the regulating rod by cooling
instantly contracts; the effect is that its contraction causes the lever to separate its
contact with the screw, and in consequence the short free circuit is broken, and the
circuit through the coil is resumed. This change of current is constant, but does.
not in any appreciable degree-lessen the illumination. It should be understood
that the electric current has a free conductor whenever the circuit by way of the;
lever is made.
In Figure 4 the connection of the conductors-is-similar_to_that_described_in_
Figure 1, except that the safety screw c and lever 91 have been provided to ensure. a
more certain contact in case a single lever and screw should fail to secure the relief
circuit, as described in Figure 1. Figure 4 also shows a form for arranging the
double glass globes or tubes.
It may be preferred to make the base piece of metal, and this may be done,
provided all connections are insulated.
Having particularly set forth a description of my Invention, and the manner of:
its operation, I claim the following as new and of my Invention :-
1st. In an apparatus for producing an electric light the automatic alternate:
switching of the current between the circuit producing the illumination and another
circuit by means of a rod or wire so arranged that its expansion and contraction
from heat produced by electricity will cause the mechanism to operate, whereby the a
proper alternation of the current between the two circuits is secured, thus providing:
a relief circuit to protect the illuminating material from fusing, as also preserving a
constant and steady light, substantially as and for the purposes herein-before
described.
2nd. The expansion of a rod or wire in combination with a regulating lever or
levers and their adjustable points, substantially as and for the purposes herein-
before described.
In witness whereof, I, the said John Edwards Stokes, have hereunto set
my hand and seal, this Eighteenth day of April, One thousand eight
hundred and seventy-nine.
JOHN EDWARDS STOKES: (L.S.)