IMPROVEMENTS IN REGULATING APPARATUS EMPLOYED IN LIGHTING BY ELECTRICITY
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office of
the Commissioners of Patents on the 10th December 1878. A communication
from abroad by François Ernest de Mersanne and Emile Bertin, both of Paris,
in the Republic of France.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN REGULATING APPARATUS EMPLOYED IN LIGHTING
BY ELECTRICITY." A communication from abroad by François Ernest de Mersanne
and Emile Bertin, both of Paris, in the Republic of France.
This Invention relates to an apparatus to be placed near the source froin which
the electricity is obtained for supplying an electric circuit connected to a number of
lamps for the purpose of indicating the intensity of the current to be supplied in
order to ensure the proper degree of incandescence in such lamps.
The apparatus may also be applied to separate circuits, along which the current
is directed in succession by means of a commutator, and serves to determine the
intensity of such currents.
The system is based upon the employment of a platinum wire arranged in the
circuit, the length and sectional area of which are calculated to equal the resistance
of the whole of the lamps to be supplied, plus one, upon which wire a sleeve or
sheath of metal of considerable sectional area is caused to slide in such a manner
that the resistance offered by the apparatus may be regulated by sliding this sleeve
or sheath along the wire.
Assuming that sixteen lamps are provided upon a circuit divided among sixteen
different consumers, the apparatus is to be placed near the machine supplying the
current, or in a situation where it will be under the control of the person entrusted
with the supply of light.
The length of wire corresponding to seventeen divisions marked upon the stand
presents a resistance equal to that of sixteen lamps, plus one, as hereinbefore
described, consequently when the current is passing in the lamps and in the
apparatus set completely open, the platinum wire cannot redden, and will remain
dark, which in this case will be the condition of the sixteen lamps of the
consumers.

page_text: Now by bringing a given point of an attachment to the sleeve or sheath gradually
nearer to the front extremity of the wire the latter will gradually become incan-
descent until a sufficiently brilliant light is obtained, when the motion is to be
arrested, and each of the sixteen lamps will then display a light of corresponding
brilliancy. If the said point has not reached a stop provided on one of the supporting
standards of the wire the length of wire between the said point and the stop will
be ineffectively incandescent; the speed of the machine or the intensity of the
current is then to be diminished until the proper length of incandescent wire is
obtained whilst retaining the same degree of light.
It will then be simply necessary to observe at this moment the colour of the wire
between the said supporting standard and the extremity of its stop in order to
ascertain the brilliancy of the lamps of the consumers, any one or more of whom
may then extinguish his or their lamps or make then shine with any desired degree
of brilliancy from the minimum to maximum degree allowed without any danger of
affecting the others, that is to say, without the liability of reducing their lights by
appropriating an undue share or of melting the wires of the others by extinguishing
his or their own lights, as the person controlling the distribution of light has it in
his power by adjusting the position of the conducting sleeve in the nut in which it
is screwed, and in which it is supported, to bring the moveable point away from the
stop, so as to replace the extinguished lights by a corresponding length of wire
without any necessity for modifying in any way the intensity of the current
supplying the circuit upon which the lamps are situate.