IMPROVEMENTS IN DISTRIBUTING ELECTRICITY FOR THE PRODUCTION OF ELECTRIC LIGHTS."
Year: 1878

page_text: LETTERS PATENT to Charles Stewart, of Islington, in the County of Middle-
sex, for the Invention of "IMPROVEMENTS IN DISTRIBUTING ELECTRICITY FOR
THE PRODUCTION OF ELECTRIC LIGHTS."
PROVISIONAL SPECIFICATION left by the said Charles Stewart at the Office
of the Commissioners of Patents on the 5th November 1878.
"IMPROVEMENTS
CHARLES STEWART, of Islington, in the County of Middlesex.
IN DISTRIBUTING ELECTRICITY FOR THE PRODUCTION OF ELECTRIC LIGHTS."
In carrying out my Invention there is a central station at which a number of
Gramme or other dynamo-electric machines for generating the electric current or
currents are worked by an engine or engines, and a distinct cable or wire is carried
from each of these machines to a corresponding number of district stations. At
each of the district stations is placed an apparatus, worked by clockwork or other
mechanism for distributing the flow of the electric current or currents.
This apparatus consists of a commutator, comprising an arm rotating rapidly
round and pressing lightly upou a disc, on the face or periphery of which are placed,
in a circle or other position, a number of metallic contact picces, insulated from each
other, and equal in number to the lights to be produced in the district. For
instance, if there be 100 lights in a district there would be 100 wires from as many
contact pieces in the commutator disc to the various lights to be produced in that
district.
The cable or wire from the Gramme or other machine at the central station is in
electric connection with the arm of the commutator through the axis on which it
rotates. Now as an object remains one eighth of a second on the retina of the eye,

page_text: it is obvious that any object which is seen more than eight times a second appears
to be constantly in view; therefore if the commutator arm rotates say ten times in
a second a current of electricity_will_be_sent-through-each-of-the-100-wires-ten-
times in a second, and if a Jablochkoff candle or other appliance for producing the
electric light.be.employed,-the-several-lights-will appear constant notwithstanding
that the current is intermittent,- being interrupted at the rate of ten times a
-second-
-
By means of my Invention any person having the electric light in his house can
-turn it on or off at pleasure without interfering with the lights of his neighbours,
since he has a separate wire from the district station.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Stewart in the Great Seal Patent Office on the 5th May
1879.
CHARLES STEWART, of Islington, in the County of Middlesex.
"IMPROVEMENTS
IN DISTRIBUTING ELECTRICITY FOR THE PRODUCTION OF ELECTRIC LIGHTS."
The object of my Invention is to enable the electricity generated by a dynamo-
electric machine (or obtained from any other source) to be distributed through a
number of circuits in succession in such a way as to permit of one or as great a
number of electric lights as may be required or found practicable being established
and maintained in each circuit by means of electric lamps.
In carrying out my Invention for lighting a town there would be a number of
Gramme or other dynamo electric machines or other apparatus for generating the
electric current or currents at a central station, and separate main wires or cables of
wires would be laid from these clectric machines to a number of district stations,
one to each, or the Gramme machines might cach be located at its corresponding
district station if preferred.
At each district station there would be a switch or commutator, worked by any
suitable motor, for distributing the flow of the electric current to the different
branch wires or circuits on which the electric lights are to be established, as herein-
after described. This switch or commutator is kept in motion at a constant speed
for putting all the branch wires in connection with the main circuit at regular and
rapidly recurring periods of time. It comprises a rapidly rotating arm terminating
in a spring contact, which passes over and presses lightly upon a number of metallic
contact pieces or pins insulated from each other and disposed at equal intervals around
the face of a disc, and equal in number to the number of branch circuits in which the
lights are to be produced in the district. The main wire or cable from the Gramme or.
other machine at the central station is in electrical connection with the arm of the
commutator through its axis.
Now as a luminous object remains for about 1/8th of a second on the retina of the
eye, it is evident that any object which is seen more than eight times in a second
will appear to be constantly visible. If therefore the commutator arm rotates say
sixty or more times in a second a current of electricity will be sent through each
of the branch wires sixty or more times in a second, and if one or more suitable
arrangements of carbons or other appliances for establishing the electric light be
interposed in the circuit of each branch wire the several lights will appear to be
constant notwithstanding that the flow of the current is intermittent, it being in fact
interrupted at the rate of sixty or more times in a second. The electric light or
lights, on any one or more of the branch circuits may be dispensed with by breaking
those circuits without in any way interfering with the others or necessitating
any alteration in the working of the commutator.
In order that my Invention may be more readily understood I will describe by
way of example one form of commutator, it being understood that I do not restrict
myself thereto, but claim as my Invention the method of distributing by means of
a rotating commutator or switch the electric current from a single main wire to a
number of branch wires in succession at equal and frequently recurring periods of
time for the production of one or more electric lights upon each or any of the
branch wires or circuits, as herein described, employing for the purpose a switch or
commutator such as I will now describe in detail, and the construction and operation
of which I also claim as part of my Invention.
Figure 1 of the annexed Drawing is a vertical section, and Figure 2 a plan of
this example of the switch or commutator for distributing the electric current to a
number of different circuits in succession, as above specified.
A is a horizontal disc of any suitable insulating material, such as vulcanite
mounted on a suitable stand, and B. are metallic contact wires, bars, or strips of

page_text: brass, iridium, platinum, copper, or other suitable metal disposed radially on the disc
at equal distances apart and fixed to or embedded in the face of said disc. When
strips are employed they would be embedded in the disc so as to present their edges
to the spring contact. To each contact wire, bar, or strip B a branch wire b is
attached by suitable binding screws, and in each branch circuit b there are one or
more pairs of carbons or other appliances. for establishing and maintaining the
electric light. C is a spring contact in the form of a comb made of steel, iridium,
platinum, or other suitable metal, and attached to the extremity of a metal arm c,
-and-so applied as to touch-the contact wires B in succession when carried round by
the revolution of a wheel or disc D, to the circumference of which said arm is
attached. The disc or wheel D is of metal, and is firmly secured on a vertical steel.
spindle E concentric with disc A, and its ends are coned and mounted to rotate
between an upper bearing F and a metal footstep G. Instead of being made of
metal; disc D and spindle E niay be made of box or other hard wood, in which case
a platinum or other wire is passed vertically through the spindle E and horizontally
along wheel D to the spring contact C, to which one end of the wire is attached,
the other end being connected to a platinum or other metal point on the foot of the
spindle. In either case the foot e of the spindle E rests on a gate g in the footstep G,
which is of cup form to contain mercury, in which the foot of the spindle is
iinmersed in order to electrically connect the metal spindle (or the platinum wire,
as the case may be), and through it the contact C with the main wire H. from the
dynamo electric or other machine or apparatus for generating electricity, the said
wire E being connected by a binding screw with the footstep G.
Or electrical connection may be otherwise established between the spindle E and
the wire H. There is a similar agate bearing for the top of the spindle, and the
spindle E is driven from a suitable motor by a belt running on a pulley I fixed on
the spindle, or by any other convenient arrangement of gearing. In order to
balance wheel D, I place a counterweight X on it opposite the arm carrying the
contact C.
The speed of the wheel D should be not less than sixty revolutions per second
at least to give a constant steady light, but may be as much higher as convenient.
K is a glass shade enclosing the disc A to protect the contacts from the moisture
of the atmosphere.
In witness whereof, I, the said Charles Stewart, have hereunto set my hand
and scal, this Fifth day of May, in the year of our Lord One thousand eight
hundred and seventy ninc.
CHARLES STEWART. (L.S.)