OR IMPROVED METHOD OF ADAPTING THE ELECTRIC LIGHT TO DOMESTIC AND OTHER ORDINARY PURPOSES."
Year: 1878

page_text: "
LETTERS PATENT to John Clark, of Kensington, in the County of Middlesex,
Engineer, for the Invention of NEW OR IMPROVED METHOD OF ADAPTING
THE ELECTRIC LIGHT TO DOMESTIC AND OTHER ORDINARY PURPOSES."
Sealed the 10th December 1878, and dated the 9th October 1878.
PROVISIONAL SPECIFICATION left by the said John Clark at the Office
of the Commissioners of Patents on the 9th October 1878.
JOHN CLARK, of Kensington, in the County of Middlesex, Engineer.
OR IMPROVED METHOD OF ADAPTING THE ELECTRIC LIGHT TO DOMESTIC AND OTHER
ORDINARY PURPOSES."
"A NEW
The object of my said Invention is first to sub-divide a strong current of elec-
tricity or magneto-electricity into any required number of lesser currents and
to use such lesser currents for producing an artificial light suitable for domestic and
other ordinary purposes, to which light by gas or other means is at present applied.
In carrying my said Invention into practice I fill a bath with mercury, and
immerse therein the ends of any required number of wires, of any suitable inetal or
metals which are conductors of electricity for the said lesser currents.
In some
cases I coat the ends of the said wires with silver or other metal to cause them to
make electric contact more certainly. The said conducting wires I prefer to make
of a uniform length, or nearly so, irrespective of the actual distance the several
places are to which such wires lead for lighting. I connect with the said mercury
bath the main conducting wire or wires for conveying electricity or magneto-
electricity to the said bath. The said electricity or magneto-electricity I produce
in the ordinary manner.
To produce the light, instead of using solid carbon or charcoal as is usual, I use
them or other illuminating media in a finely divided state as dust, and I place
such dust between slips of glass or other transparent material. The electricity or
magneto-electricity in passing through such dust causes it to become incandescent,
but in a subdued degree.

page_text: I fit a corresponding set of return conducting wires of equal length, or nearly so,
and terminate the same in a suitable mercurial bath, from which I lead a prime
conducting wire to the earth or opposite pole of the battery of the first-described
main wire or wires.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Clark in the Great Seal Patent Office on the 9th April
1879.
JOHN CLARK, of Kensington, in the County of Middlesex, Engineer. "A NEW
OR IMPROVED METHOD OF ADAPTING THE ELECTRIC LIGHT TO DOMESTIC AND
OTHER ORDINARY PURPOSES."
The object of my said Invention is first to sub-divide a strong current of elec-
tricity or magneto-electricity into any required number of lesser currents of equal
tension; and second, to use such lesser currents for producing an artificial light
suitable for domestic and other ordinary purposes, to which light by gas or other
means is at present applied, by conducting the lesser currents through a suitable
illuminating medium placed in the circuit of such currents.
In carrying my said Invention into practice I fill or partially fill a bath with
mercury, and immerse therein the ends of any number of wires of any suitable
metal or metals which are conductors of electricity for the said lesser currents. In
some cases I coat the ends of such wires where they dip into the mercury with
silver or other metal to cause them to make electric contact more certainly. In
certain cases I also solder or braze the ends of the said conducting wires together
in a pile and dispense with the said mercury bath. The said conducting wires I
prefer to make of a uniform length, or nearly so, irrespective of the actual distance
of the several places to which such wires lead for lighting purposes, my object
thereby being to attain a uniform resistance in the several wires composing such
pile, and thus to subdivide the greater current of clectricity into a number of
lesser currents, corresponding with the number of wires in such pile of an equal
resistance each to each, or nearly so.
I connect with the said mercury bath or with the soldered pile of conducting
wires the main conducting wire or wires for conveying the electricity or magneto-
electricity to the said bath or pile. The main current or currents of electricity or
magneto-electricity I produce in the ordinary manner by any machine or apparatus
suitable for such purpose.
To produce the electric light instead of using solid carbon or charcoal in rods or
plates as is usual, I use them or other illuminating media in a finely divided state
as dust or powder, and place such dust or powder between strips of glass or other
transparent or semi-transparent material, or such glass or other material may be
tubular, having the said dust or powder placed inside; or any other suitable form
of glass or other material may be used, my object being to keep the said dust or

page_text: powder from contact with the oxygen of the air, and to keep such dust in a com-
pacted state as required. To more effectually protect such dust or powder from
being acted on by oxygen gas I also enclose the said glass strips, tube, or other
transparent material in a larger outer globe of any suitable kind, and fill the said
globe with any gas other than oxygen or its compounds. In some cases I prefer to
use instead of the dust or powder described the material called asbestos, either as
powder or in a compact state, or compounds formed with it, or the chromate of iron
ore, or the bichromate of potash.
The conducting wires previously described for the lesser currents are each fitted
to conduct electricity or magneto-electricity, so that it will pass through a stratum
or portion of the said dust, powder, or asbestos, and in consequence of the current
so passing, it illuminates such stratum to incandescence to produce electric light in
connection with each wire of which the said pile or group is composed.
When I use asbestos in a compact form I may dispense with the strips or tube of
glass or other transparent material previously described, as these are mainly
intended to keep in a collected state the illuminating medium when used as dust
or powder. The property of asbestos to resist destruction by fire is well known,
and I find it very suitable for durability when applied as an incandescent medium
for producing the electric light. In using asbestos I do not always operate with
it through a number of wires or other suitable conductors of equal length as des-
cribed, for in some cases I use a single main wire with a succession of breaks in it,
and place in such breaks short connecting pieces of asbestos or its compounds,
either in powder or compact, in order to keep entire the conductivity of the said
main wire, so that by passing a current of electricity or magneto-electricity along
such main wire, the said pieces of asbestos are illuminated simultaneously by the
passing of such current.
When I subdivide the main current of electricity or magneto-electricity by
passing it through a number of wires of equal length as described, I in some cases
modify this arrangement by making some of the wires shorter in the pile or group
and of different metals, the shorter wires being metals of less conducting power
than the longer wires of such pile or group, or by making some of the wires of the
pile or group of less sectional area at a part of their length; in both cases I obtain
a uniformity of resistance to the electric current in the several wires grouped
together to form a series. For the same object in another modification I make a
break in each wire in the series and immerse the separated ends in a bath of
acidulated water or other liquid of less conducting power than the metal of which
the conducting wires are made, or I insert such separated ends in a receiver filled
with charcoal dust or powder similar to that described for producing the electric
light. The ends of the said wires are adjustable at the breaks as to their distance
apart, so that instead of maintaining a uniform resistance in the pile or group of
wires by making them of a uniform length as described, I attain the same object
by making the said wires of unequal length and adjusting the breaks in the said
bath, or by compressing the said charcoal dust or powder by screws fitted to the
said bath or receiver, or by other suitable means, to obtain a uniform resistance
in such conducting wires forming such pile or group; or I adjust the ends of the
said wires where the breaks occur for the illuminating medium to be placed.
I have hitherto described the subdivision of the clectric current on the main
wire as referring to one pile or group of secondary wires only, but in practice I do
not limit myself to one pile or group of such wires, as in certain cases theso
secondary wires may be further subdivided in a similar manner to that described
as far as the strength of the main electric current will admit of, or the circum-
stances of the case inay require.
I avail myself of all well-known details, such as insulating the said conducting
wires, or for making and breaking contact by switches, or other well-understood
arrangements for other purposes when required.
Having thus particularly described and ascertained the nature of my said Invon-
tion and the method of performing the same, I further state that I do not restrict

page_text: myself to the precise details herein described, because from the nature of my said
Invention these may be considerably modified without departing from the chicf
characteristics of my said Invention, but what I specifically claim as novel, and
desire to sucure by the before-mentioned in part recited Letters Patent is,―
Firstly. The method of subdividing a strong current of electricity or inagneto-
electricity by passing it through a number of secondary wires of equal length and
thickness, substantially as described.
Secondly. The modified method of attaining a similar result by making the
secondary wires of metals of different conducting powers, or by reducing the
sectional area of the wires when made of the same or similar metal, or by making
a break in the said wires and adjusting the distances of the separated ends, sub-
stantially as described.
Thirdly. The method of producing electric light by illuminating a portion of
carbon, or charcoal dust or powder, placed in a circuit of such electric current,
substantially as described.
Fourthly. The method of producing electric light by illuminating a portion of
asbestos, chromate of iron ore, or bichromate of potash, placed in the circuit of such
current, substantially as described.
Fifthly. The method of preventing the oxidation of the illuminating medium by
enveloping it in an outer globe or case filled with any gas other than oxygen or
its compounds, substantially as described.
In witness whereof, I, the said John Clark, have hereunto set my hand and
seal, this Eighth day of April, in the year of our Lord! One thousand eight
hundred and seventy-nine.
JOHN CLARK. (L.S.)