IMPROVEMENTS IN ELECTRIC- "
Year: 1882

page_text: LETTERS PATENT to John Medley Stuart, of Queen Victoria Street, in the
city of London, Engineer, for an invention of IMPROVEMENTS IN ELECTRIC-
"
PROVISIONAL SPECIFICATION left by the said John Medley Stuart at
the Office of the Commissioners of Patents on the 11th May 1882.
JOHN MEDLEY STUART of Queen Victoria Street in the City of London Engineer
"IMPROVEMENTS IN ELECTRIC LAMPS"
This Invention relates to that class of electric lamps in which the light is
produced and maintained in a vacuum The invention consists of the application
and combination of the herein-after described materials for the purposes specified.
Into the opening of the globe in which the light is to be produced I introduce
through the stopper or plug two fine glass tubes within which are sealed the
preferably platinum wires which conduct the current The wires do not extend
the full length of the tubes but terminate at a little distance from the interior
ends of said tubes. The air in the globe is rarefied by the use of ether or other
suitable substance, and is then exhausted from the globe, into which is then
introduced a small quantity of carbonic acid, the air in the globe being again
exhausted as perfectly as possible and the globe sealed If a current of electricity
be then passed through the globe a steady soft light will be given out from the
small tubes through one of which the current will enter and be then conducted to
the other by attraction and condensation, the carbonic acid becoming gas by the
action of the heat given out by the current in passing through the globe If it is
desired to have an incandescent carbon light I attach to the extremities of the
wires in the tubes a thin carbon fibre which I prefer should be animal carbon and
this may be conveniently and advantageously prepared from horse hair which may
be carbonised and bent in the usual manner Instead of using animal carbon alone
I may use a combination of animal and vegetable or mineral carbon and instead
of two small tubes and wires I may introduce four or more tubes into the globe,
the currents crossing the lamp at right or other angles to each other

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Medley Stuart in the Great Seal Patent Office on the
11th November 1882.
JOHN MEDLEY STUART of Queen Victoria Street in the City of London Engineer
IMPROVEMENTS IN ELECTRIC LAMPS
This Invention relates to that class of electric lamps in which the light is
produced and maintained in a. vacuum The invention consists of the application
and combination of the hereinafter described materials for the purposes specified
Into the opening of the globe in which the light is to be produced I introduce
through the stopper or plug two fine glass tubes of about inch in diameter and
within which are sealed the preferably platinum wires which conduct the current
The wires do not extend the full length of the tubes, but terminate at a distance
of say to an inch from the interior ends of said tubes while the tubes themselves
extend to approximately the centre of the globe.
The air in the globe is rarefied by the use of ether or other suitable substance
and is then exhausted from the globe in which is then introduced a small quantity
of carbonic acid, the air in the globe being again exhausted as perfectly as possible
and the globe sealed If a current of electricity be then passed through the globe,
a steady soft light will be given out from the small tubes, through one of which
the current will enter and then pass to the other, the carbonic acid becoming gas
by the action of the heat given out by the current in passing through the globe.
If it is desired to have an incandescent carbon light, the tubes may or may not
extend so far into the globe, while I attach to the extremities of the wires in any
suitable manner in the tubes, a thin carbon fibre which I prefer should be animal
carbon and this may be conveniently and advantageously prepared from horse hair
which may be carbonised and bent in the usual manner. Instead of using animal
carbon alone I may use a combination of animal and vegetable carbon such as a
cotton fibre around which horse hair is wound or mineral carbon may be employed
instead of the cotton fibre, or a combination of animal, vegetable and mineral
carbon as I have found by experiment that asbestos soaked in melted sugar and
then wound with horse hair which is subsequently carbonised, will give very
advantageous results Instead of two small tubes and wires I may introduce four
or more tubes into the globe, the currents crossing the lamp at right or other
angles to each other The globes themselves I prefer to make of phosphorous
iridescent glass but ordinary glass may be employed I am aware that it has
before been proposed to use vegetable carbon and also animal carbon for incan-
descent lights and I do not claim the use of either of these or of mineral carbon
alone as being my invention but What I do claim and desire to secure by Letters
Patent is
1st In electric lamps in which the light is produced in a vacuum the application
and use of tubes entering the globe and which contain through part of their length
the requisite conducting wires substantially as and for the purposes set forth
2nd In electric lamps of the incandescent type the application and use of animal
carbon, combined with vegetable or mineral carbon or both substantially as set
forth
3rd The method of manufacturing electric lamps of the vacuum type as described

page_text: consisting of first rarifying the contained atmosphere by the use of ether, then
exhausting, then introducing carbonic acid and again exhausting and sealing all
substantially as and for the purposes set forth
In Witness whereof I the said John Medley Stuart have hereunto set my
hand and seal this tenth day of November in the year of Our Lord one
thousand eight hundred and eightytwo.
Signed, sealed and delivered
in the presence of
ALLEN P JONES
53 Chancery Lane
London W.C
JOHN MEDLEY STUART (LS)