Improvements in Warming Soles for Boots and Shoes.
Year: 1891

page_text: Date of Application, 2nd July, 1891-Accepted, 24th Oct., 1891
COMPLETE SPECIFICATION.
Improvements in Warming Soles for Boots and Shoes.
I, OTTO VOIGT of 41 Thacrsti. of Berlin, Germany, Master Butcher, 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 object of the present invention is to construct a sole which may be inserted
in boots or shoes, for keeping the feet warm, not merely by keeping in the
natural warmth of the foot but by generating heat in the said sole underneath
the foot.
I attain this object by means of the device hereinafter more particularly described
and illustrated in the accompanying drawing, in which similar letters denote
similar parts throughout the several views.
Fig. 1 is a view of the sole seen from underneath and
section along line az in Fig. 2 and
Fig. 2 shows a vertical section along line y y in Fig. 1.
representing a partial
As far as applicant is aware the soles for keeping the feet warm, in use up till
now, attain this object only in so far as they keep in the natural warmth of the
foot, by the sole being made to form a loose, badly conducting layer between the
foot and boot.
Such devices are, however in so far inadequate, in that, as soon as the foot loses
its natural warmth owing to the cold outside, the warming sole loses its effect and
the foot remains in a cold condition.
In the accompanying drawings a hollow sole is represented, formed of thin copper
plate and having its bottom flat but made deeper at the heel end of the boot. The
upper surface of the sole is formed to fit the sole of the foot whilst the interior
of the boot itself must be made to fit the under surface a of the metallic sole.
This hollow sole is divided into two parts by means of a horizontal partition e
which is, however provided with holes e and fat the front and back end, i.e. the toe
and heel ends of the boot, so that the two compartments A and B are not entirely
divided from each other.
In the heel compartment A of the hollow sole a socket d is arranged for the
reception of the source of heat. The interior of the sole is now completely
filled with warm water and a suitable heat generator arranged in the socket d.
In the arrangement shown in the accompanying drawing the heat generator
consists of a double coil of some material which is a bad conductor of electricity.
The ends of the coil are then attached to a so called pocket battery by means of
insulated wires such battery being easily concealed on the person of the wearer.
The coil will thus he brought almost to a glow heat, and communicate this heat
to the air in the socket d and thus to the water in the sole, continually heating the
latter.
The water thus heated in the compartment A rises along the slanting plate c
underneath the same, to the toe end of the boot through the opening e into the
upper compartment B. After having transmitted its heat or a part of the same to
the foot it returns to the lower chamber by way of the opening f, it is here again
warmed and continues to repeat the circuit.
In order to prevent the heat from escaping at the under side of the hollow
sole the same is provided with a layer of some material which does not conduct
heat.
Instead of heating by electricity, a slow burning vegetable carbon may be
arranged in the socket d or the water may be heated by introducing unslaked lime

page_text: or some chemical substance having the property of generating heat on combining
with water.
If it is only necessary to use the boots for a short time no heat generator is necessary
as it will be found sufficient to fill the sole with warm water.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1). A sole for maintaining a constant warm temperature under the foot, con-
sisting of a metallic casing containing water or other suitable liquid and a socket for
containing the heat generator, arranged in the heel end of the said sole as
described.
2). The combination of the flat lower plate a deepened at the heel end and the
upper plate having the form of the sole of the foot, said two plates forming
together a hollow sole which is divided into compartments by means of the
sloping horizontal plate e having holes ef as specified, said sole being provided
with socket d at the heel end for the purpose substantially as described.
Dated this 2nd day of July 1891.
RAYNER & CASSELL,
37, Chancery Lane, London, W.C., Agents for the Applicant.