IMPROVEMENTS IN SYSTEMS OF ELECTRIC LIGHTING
Year: 1881

page_text: LETTERS PATENT to Edward Griffith Brewer, of 38, Chancery Lane, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN SYSTEMS OF
ELECTRIC LIGHTING." A communication from abroad by Thomas Alva
Edison, of Menlo Park, in the State of New Jersey, United States of America,
Electrician.
PROVISIONAL SPECIFICATION left by the said Edward Griffith Brewer
at the Office of the Commissioners of Patents on the 4th May 1881.
EDWARD GRIFFITH BREWER of 33 Chancery Lane in the County of Middlesex
"IMPROVEMENTS IN SYSTEMS OF ELECTRIC LIGHTING." A communication from
abroad by Thomas Alva Edison of Menlo Park in the State of New Jersey
United States of America, Electrician.
"
In the so called and well known Edison" system of electric lighting wherein
very many lamps are to be supplied from one central station, it is essential that
the electro motive force or pressure throughout the system be maintained
constant.
In such systems the lamps are so proportioned as to radiating surface and
resi-tance that all the lamps in a system shall give a standard amount of light.
Under some conditions it is desirable that provision should be made enabling.
lamps giving less than the standard amount of light to be used in a system with
standard lamps without any additional devices such as resistances.
The object of this Invention is to furnish a method for attaining this object.
The Invention consists in diminishing the radiating surface and increasing the
resistance of the lamp in the ratio which the diminished lamp bears to the standard
lamp.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Edward Griffith Brewer in the Great Seal Patent Office on
the 4th November 1881.
EDWARD GRIFFITH BREWER of 33 Chancery Lane in the County of Middlesex.
"IMPROVEMENTS IN SYSTEMS OF ELECTRIC LIGHTING." A communication from
abroad by Thomas Alva Edison of Menlo Park in the State of New Jersey
United States of America, Electrician.
In a system of electric lighting wherein very many lamps are to be supplied from
one central station, it is essential that the electro-motive force or pressure throughout
the system be maintained constant. In such systems the lamps are so proportioned
as to radiating surface and resistance, that all the lamps in a system shall give a
standard amount of light.
Under some conditions it seems desirable that provision should be made enabling
lamps giving less than the standard amount of light to be used in a system with
standard lamps without any additional devices such as resistances, etc.
That is, supposing that a lamp giving under the normal pressure of current in
the system 16 candle power to be taken as the standard, it may be desirable to
use in the same system, lamps giving 4, 6, 8, or 10 candle power.
The object of this Invention is to furnish a method for attaining this object.
This method may be briefly stated as consisting in diminishing the radiating
surface and increasing the resistance of the lamp in the ratio which the diminished
lamp bears to the standard lamp.
In the Drawing suppose 1, 2, to be main conductors, upon multiple ares thereto,
3, 4, 5, the lamps 4, 8, 16, being placed.
Suppose that the conditions are such that with the standard radiating surface
and resistance of the lamps, and standard pressure of the system, the lamp 16 gives
16 candle power then if in 8 the radiating surface is diminished one half while
the resistance is doubled in comparison with the standard lamp, this lamp may
be used in the same system with the standard lamp but will give only 8 candle
power, or to put it in figures, suppose the resistance of the standard lamp to be
100 ohms and its radiating surface 10 millimeters, to use in the same system the
lamp 8 its carbon c must have a resistance of 200 ohms and a radiating surface of
5 millimeters. Applying the same method, the lamp 4 may be made to give 4
candle power, and other lamps may be introduced giving any desired candle
power.
What is claimed is,―
First, In a system of electric lighting in which a constant and uniform pressure
of current is maintained, the combination of lamps varying in radiating surface
and resistance, substantially as set forth.
Second. The method of varying the light-producing power of electric lights for
use in one system, consisting in diminishing the radiating surface and increasing
the resistance in proportion as they are to vary from the standard lamp, substantially
as set forth.
In witness whereof I the said Edward Griffith Brewer have hereunto set
my hand and seal this First day of November in the year of our Lord
One thousand eight hundred and eighty-one.