Electrical Influence Machines.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Electrical Influence Machines.
I, WINTER RANDELL PIDGEON, Engineer, of 42, Porchester Square, London,
W., do hereby declare the nature of this invention to be as follows:-
One form of machine Figs. I. & II. consists of one or more pairs of glass (or
ebonite) discs mounted on a spindle and running in opposite directions, with
earthing brushes and collectors arranged similarly to the well known Wimshurst
machine. The discs may be of ordinary glass, and are covered to within three
or four inches of the centre with sectors (S) about an inch or an inch and a half
wide at the circumference and placed about one eighth of an inch apart.
These sectors stand radially and each carries a small brass contact knob.
The discs are flooded with wax, composed of about half paraffin and half rosin
by weight, which covers up and insulates the whole of each sector except the
small brass contact knob which peeps above it.
Each of the earthing brushes passes through and supports a fixed insulated
inductor "A," which is formed of tin foil stuck to an ebonite backing and insu-
lated with wax. The surface of the wax on all the inductors and discs is carefully
varnished several times with filtered shellac, to protect the wax and give it a
hard surface. Each inductor is kept charged by a stationary point "B" con-
nected to it and placed so as to collect, from the revolving disc, shortly before
the main collecting brushes "C."
The sectors on each of the discs are earthed at the moment when they are
passing between the opposite dise on the one hand and the fixed inductor on the
other, both of which carry a charge of the same sign. The sectors therefore
receive their charge at a moment when their capacity is at a maximum, owing
to their standing between two charged inductors. As each sector moves away
from the brush to the right and out of the influence of the inductor, its capacity
decreases and therefore its potential rises, and when it is opposite the point at
which its fellow disc is being earthed, its potential is much higher than in the
Wimshurst form of machine, and it therefore induces a proportionately higher
charge on the sector being earthed.
This sector, as it moves away from its inductor to the left, again rises in poten-
tial, and on arriving at the earthing brush induces a still higher potential on
the sectors moving to the right. This cumulative action goes on in a sort of
arithmetical progression until, as a matter of fact, the output of this form of
machine rises to three or four times that of the Wimshurst form of machine of
a similar size, when measured by the overflow of a Leiden jar.
Fig. 3 shows diagramically another form of influence machine I make by

page_text: mounting several rings or short tubes of different diameters concentrically on
a dise A, so that the smallest surrounds the centre, the next larger surrounds
that, and the next larger surrounds that again, and so on. On another disc "B"
I mount a similar series of rings or short tubes of such diameters that they will
interspace with the first set. I bring these two sets together and revolve the one
inside the other in opposite directions. Each of the tubes carries, or may be
built up of, sectors, which are insulated with wax and which have a contact knob
C" connected to them placed on the opposite side of the disc to that to which
they are attached. Earthing brushes and collectors are arranged to touch these
contact knobs in the same way as they are in a Wimshurst machine.
66
I am aware that there is a cylindrical form of Wimshurst machine, which is
different from my machine in that by my arrangement the plates are influenced
on both sides at once and thus the output of the machine is greatly increased.
Dated this 9th day of July 1898.
Electrical Influence Machines.
I, WINTER RANDELL PIDGEON, Engineer, 42, Porchester Square, London, W.,
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement:-
The
One form of machine consists of one or more pairs of glass (or ebonite) discs
mounted on a spindle and running in opposite directions, with earthing brushes
and collectors arranged similarly to the well known Wimshurst machine. The
discs may be of ordinary glass and are covered to within 3 or 4 inches of the
centre, and to within 1" of the circumference with sectors S. shewn on Sheet 1
of the drawings which were left with the Provisional Specification, about an
inch or an inch and a half wide at the circumference and placed about one-eighth
of an inch apart. These sectors stand radially and each carries a small brass
contact knob. The discs are flooded with wax, composed of about half paraffin
and half rosin by weight, which covers up and insulates the whole of each sector
except the small brass contact knob which peeps above it. Each of the earthing
brushes passes through and supports a fixed insulated inductor "A," which is
formed of tin foil stuck to an ebonite backing and insulated with wax.
surface of the wax on all the inductors and discs is carefully varnished several
times with filtered shellac, to protect the wax and give it a hard surface. Each
inductor is kept charged by a stationary point "B" connected to it and placed
so as to collect, from the revolving disc, shortly before the main collecting
brushes "C." The sectors on each of the discs are earthed at the moment when
they are passing between the opposite disc on the one hand and the fixed inductor
on the other, both of which carry a charge of the same sign. The sectors there-
fore receive their charge at a moment when their capacity is at a maximum,
owing to their standing between two charged inductors. As each sector moves
away from the brush to the right and out of the influence of the inductor, its
capacity decreases and therefore its potential rises, and when it is opposite the
point at which its fellow disc is being earthed, its potential is much higher than
in the Wimshurst form of machine, and it therefore induces a proportionately
higher charge on the sector being earthed. This sector, as it moves away from its

page_text: inductor to the left, again rises in potential, and on arriving at the earthing
brush induces a still higher potential on the sectors moving to the right. This
cumulative action goes on in a sort of arithmetical progression until, as a matter
of fact, the output of this form of machine rises to three or four times that of
the Wimshurst form of machine of a similar size, when measured by the overflow
of a Leiden jar.
The mounting and driving of the discs in opposite directions may be similar
to that in the well-known Wimshurst machine.
"
Fig. 3 shows diagramatically another form of influence machine I make by
mounting several rings or short tubes of different diameters concentrically on a
disc "A so that the smallest surrounds the centre, the next larger surrounds
that, and the next larger surrounds that again, and so on. On another disc B
I mount a similar series of rings or short tubes of such diameters that they will
interspace with the first set. I bring these two sets together and revolve the one
inside the other in opposite directions. Each of the tubes carries, or may be built
up of, sectors which are insulated with wax and which have a contact knob "C"
connected to them placed on the opposite side of the disc to that to which they
are attached. Earthing brushes and collectors are arranged to touch these con-
tact knobs in the same way as they are in a Wimshurst machine.
I am aware that there is a cylindrical form of Wimshurst machine, which is
different from my machine in that by my arrangement the plates are influenced
on both sides at once and thus the output of the machine is greatly increased.
Perhaps the best way to build this machine is to make a suitable mould for
either half of the machine, which mould is then filled with rubber in its plastic
state. The sectors, made of thin sheet metal, and each having a shank carrying
a collecting knob attached, are placed and held in their right position in the
soft mass by a jig or part of the mould, and the whole is then vulcanised in the
ordinary way, so that each disc, together with the tubes that it carries, is
ultimately formed of one piece of ebonite.
Another method is to turn a groove in the face of the discs for each tube and
bend round sheets of ebonite, each tube being formed of two such sheets bent
round, and carrying the sectors in between them. These sheets are held into
the groove by screws put in from the other side of the disc and tapped in between
the two sheets. A transverse groove is also ploughed in the sheet ebonite between
each pair of sectors, which groove is ultimately filled with wax or other insulating
material, so as to separate the sectors electrically.
Yet another method is to wrap a thin sheet of ebonite round three or four
times and place it in the groove cut in the face of the disc. The sectors are
pasted on to this sheet so that, when it is bent round, they come between the
folds and are so spaced that no two come in juztaposition. Perhaps this is more
clear if we think of one tube being built of three thin strips of ebonite wrapped
round, the central strip carrying all the odd sectors on one face and all the even
ones on the other. In this case the distance apart of the sectors is sufficient to
insulate them. The sectors in each tube should be from 18 to 30 or 40 in number
according to the diameter of the tube, and in this last case they need not be
large, as the absence of wax enables the electrical charge to spread over the face
of the ebonite between the sheets.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. The influence machine as shewn on Sheet 1 and substantially as described.
2. Insulating the sectors all except a small contact knob by flooding discs of
ebonite, glass, or other suitable insulating material, with wax, substantially as
described.
3. The combination of discs carrying insulated sectors together with inductors,
substantially as described.

page_text: 4. The influence machine as shewn on Sheet 2, and substantially as described.
5. The arrangement of concentric rings of insulated sectors, whether carried
by tubes of any suitable insulator or formed of sectors standing separately, by
which means each of the sectors on one half of the machine can be influenced by
the sectors on the other half of the machine on both sides at once, substantially
as described.
Dated this 10th day of February 1899