Improvements in Electrically Conducting Soles and Heels for Rubber and other Non-conducting Soled Footwear.
Year: 1896

page_text: Date of Application, 21st Dec., 1896-Accepted, 13th Mar., 1897
COMPLETE SPECIFICATION.
Improvements in Electrically Conducting Soles and Heels for Rubber
and other Non-conducting Soled Footwear.
I, GEORGE FREDERICK REDFERN, of the Firm of G. F. Redfern & Co.,
The General Patent Office, No. 4, South Street, Finsbury, in the County of
London, Patent Agents, do hereby declare the nature of this invention (a com-
munication to me by James Grey Pennycuick, of 100, Stanley Street, in the City
of Montreal in the County of Hochelaga, in the Province of Quebec, Canada,
Manufacturer,) and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
My invention relates to improvements in the construction of soles for rubber and
other footwear, the soles of which, as ordinarily constructed, are electrically
nonconducting, and the object of the invention is, without causing the sole to
leak, to provide good electrical connection between the outside of the sole where
it comes in contact with the ground and the inside where the foot or the inner shoe
comes in contact with it, in order that there may be good electrical connection
hetween the body of the wearer and the ground, so as to allow the electric state
of the body to be always the same as that of the surrounding earth and thus
prevent that electric tension which prevails, causing discomfort and even impairing
the health, where the body is insulated from the earth, and it consists essentially in
forming the sole with a base of metallic or other good electrically conducting
material, to the inside of the nonconducting part or outer sole and so arranged
that a plurality of projections forming part of the inner conducting material,
extend through to the outer surface of the outer sole, as hereinafter more
particularly explained and shown in the drawings attached hereto.
Fig. 1 is a perspective view of the under side of a rubber shoe made in
accordance with my invention, with part of the sole and inner lining broken away,
in order to show my preferred form of construction.
Fig. 2 is a longitudinal vertical section of a rubber shoe made in accordance
with my invention, resting on the ground and having a foot and inner shoe in
section shown therein.
Fig. 3 is an enlarged perspective detail of part of the sole as shown in Fig. 1,
sufficient to show more clearly the preferred form of construction.
Fig. 4 is a perspective view of the under side of the heel of a rubber shoe,
partly broken away, showing an alternative form of construction.
Fig. 5 is an enlarged detail of rivet shown in Fig. 4, before insertion into the
shoe.
Fig. 6 is an enlarged detail of portion of the heel shown in Fig. 4, with the rivet
in place and clinched.
In the drawings like letters of reference indicate corresponding parts in each
figure.
A is the electrically nonconducting under part of a shoe, being composed of the
sole a and the heel a¹. B is a netting of fine copper or other suitable wire, having
outwardly turned ends b at desired distances apart throughout. In making the
shoe, this previously prepared netting B is placed upon the outer side of the inner
cloth lining C, preferably only on those parts where the shoe will bear most directly
upon the ground, and has the outwardly turned ends b pointing straight outwardly.
Of course this netting can be made sufficiently large to extend throughout the

page_text: whole length of the shoe, but I prefer merely using two small strips, one under
the ball of the foot and the other across the heel as shown.
This I find is quite sufficient for good electrical-connection and does not impair
the elasticity of the sole.
After placing the netting as described, the rubber, or other electrically non-
conducting composition A', of which the sole and heel are to be made, is applied
to the cloth C and the netting B in a state sufficiently plastic to allow the outwardly
turned points of wire b to pierce through, they being made just sufficiently long to
reach the outer surface, and the shoe is moulded into shape and allowed to harden
in the ordinary way.
Very fine wire, I find, is sufficient to carry the current of electricity that will be
required to pass between the body and the earth, which current, at its greatest,
will be but feeble, as the difference of potential between the human body and the
earth is, under ordinary circumstances, never great. At the same time, by having
the wire very fine there will be the least chance of leakage of water, between it
and the surrounding material, the wire being very pliable and having a surface for
the material to adhere to, great in proportion to its sectional area, in proportion as
that area is small, for, it is well known, that the proportion of surface to volume,
of a wire varies inversely as its diameter.
When the shoe is worn, the points of wire b at the surface of the sole and heel
are brought into direct contact with the earth and thus, though very small, make
good electrical connection therewith. On the inside, however, since I ordinarily
place the wire between the inner cloth lining and the rubber or other material of
which the sole and heel are made, and as the electric current has to pass through
such cloth and generally through the sole or heel of an inner shoe as well as the
stocking, all of which are more or less imperfect conductors, a large area of contact
is needed. This is provided by the ramifications of the wire mesh, which give a
comparatively great area of contact.
In order to facilitate the easy flow of electricity from the wire to the body, or
vice versa, I preferably join the netting in the sole with that in the heel by the
wires placed between the cloth lining and the main body of the sole and heel
and with the ends in contact with both nettings. Thus if one part of the sole or
heel afford an easier passage for the current to or from the body than the rest, the
electric current from every part of the wire netting, whether in the sole or heel,
will have ready access thereto and it will be free to follow the path of least
resistance.
It has generally been found that no inconvenience is incurred by the use of
leather or other electrically conducting footwear. When however, rubber or other
nonconducting soles are used, considerable discomfort and even loss of health are
experienced, which has led to a strong popular prejudice against the use of such
articles. This inconvenience I felt before my invention and the use of my means
for electrically connecting the body with the earth, but the use of such means
removes all trouble and rubber shoes become as healthful and comfortable as those
made of leather.
Where the inner lining of the shoe is made of insulating or even of very poorly
conducting material, I find it necessary or advisable to place the wire netting on
the inside, with the outwardly turned wire ends passing through both lining and
sole or heel, or else, to place the netting between the lining and sole or heel as
before described, but with the ends of wire or strands thereof, passing backwardly
through the lining as well as forwardly through the rubber or other material, the
wire ends protruding through the lining, being beat back and having the points
imbedded in the lining, or otherwise arranged so as not to interfere with the
convenient use of the shoe.
In Figs. 4, 5 and 6 I show an alternative form of electrical conductors, which
I use more particularly with rubbers and such like, already manufactured, to which
they may be attached, even after the rubber has been worn for some time.
I insert one or more copper or other suitable electrically conducting rivets B

page_text: into as many holes pierced in the sole or heel of the shoe. The rivet B' has a
broad, conical head or cap , recessed on the inside, and having the annular lip b*
and the hollow shank 6 pointing inwardly. This shank, after being pressed
through the hole from the outside, is outwardly turned or clinched by a suitable
instrument and buries itself in the inner lining and material of the sole and heel,
the cup shaped inner side of the head 6' being drawn tightly against the outer side
of the sole or heel, and the annular lip 6 burying itself therein, thus effectually
preventing all danger of leakage around the rivet.
The heads of the rivets so made also serve the purpose of "creepers," preventing
the foot from slipping on the ice or snow.
If, in any case, the material of which the sole or heel is made, is not sufficiently
firm to enable the outwardly turned lip 6 of the hollow shank to retain the
rivet B in position, a washer can be inserted over the end of the shank before it is
turned over, thus giving a broader retaining surface on the material.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what mauner the same is to be performed, I declare that what I
claim is ;-
1. An electrically conducting sole for rubber or other nonconducting soled
footwear, comprising a base of electrically conducting material secured upon the
inside of the nonconducting sole or heel and one or more projections attached to or
forming part of the same and extending through the nonconducting sole or heel, to
the outer under surface thereof, as and for the purpose specified.
2. An electrically conducting sole for rubber or other nonconducting soled
footwear, comprising a base of wire mesh, secured upon the inside of the non-
conducting sole or heel, and projecting wires of the mesh extending outwardly
through the nonconducting sole or heel to the outer under surface thereof, as and
for the purpose specified.
3. An electrically conducting sole for rubber or other nonconducting soled
footwear, comprising an inner sectional base of wire mesh for the tread portion of
the sole and projections attached to or forming part of the mesh extending through
such tread portion of the sole to the outer under surface thereof, a sectional inner
base of wire mesh for the heel tread and projections attached to or forming part of
the mesh, extending through the heel tread to the outer under surface thereof, as
and for the purpose specified.
4. An electrically conducting sole for rubber or other nonconducting soled
footwear, comprising an inner sectional base of wire mesh for the tread portion of
the sole and projections attached to or forming part of the mesh extending through
such tread portion of the sole to the outer under surface thereof, a sectional inner
base of wire mesh for the heel tread and projections attached to or forming part of
the mesh, extending through the heel tread to the outer under surface thereof and
longitudinal wires connecting the two sections of wire mesh, as and for the purpose
specified.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.