IMPROVEMENTS IN INSULATORS FOR TELEGRAPHIC WIRES
Year: 1867

page_text: LETTERS PATENT to George, Davies, of No. 1, Serle Street, Lincoln's Inn,
in the County of Middlesex, and No. 87, St. Vincent Street, in the
City of Glasgow, Civil Engineer and Patent Agent, for the Invention
of "IMPROVEMENTS IN INSULATORS FOR TELEGRAPHIC WIRES."-A com-
munication from abroad by David Brooks, of Philadelphia, Pennsylvania,
in the United States of America.
Sealed the 29th October 1867, and dated the 29th July 1867.
PROVISIONAL SPECIFICATION left by the said George Davies at the
Office of the Commissioners of Patents, with his Petition, on the
29th July 1867.
I, GEORGE DAVIES, of No. 1, Serle Street, Lincoln's Inn, in the County
of Middlesex, and No. 87, St. Vincent Street, in the City of Glasgow,
Civil Engineer and Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN INSULATORS FOR TELEGRAPHIC WIRES," (a
communication to me from abroad by David Brooks, of Philadelphia,
Pennsylvania, in the United States of America,) to be as follows:-
This Invention consists, firstly, in the use of paraffine in the manner
described hereafter as an insulating medium in the construction of insulators
for telegraph wires.

page_text: Secondly, in the use of blown glass as an insulating medium in the con-
struction of such insulators.
Thirdly, in an improved construction of insulator, as fully described
hereafter, which is more efficient and durable than those of the usual
construction.
And, fourthly, in a means (described hereafter) of preventing the damaging
effects of lightning upon telegraphic insulators.
The first part of the Invention, which relates to the use of paraffine as an
insulating medium, is applicable to the ordinary or most familiar form of
insulator, which consists of an earthenware or porcelain block having two
annular flanges or cups, with a socket in the interior for the reception of the
upper end of the post; this earthenware or porcelain insulator, while still fresh
from the kiln and retaining some degree of heat, is immersed in molten
paraffine and allowed to remain so until its pores have been completely filled
with that substance. When the insulator thus prepared is to be applied to a
wooden post or bracket, that end of the latter to which the insulator is to be
attached is first heated to expel as much as possible of its moisture, and then
while still warm is dipped into molten paraffine, with which it thus becomes
thoroughly saturated. By this means the various parts of the insulator, as
well as that portion of the post or bracket immediately in contact therewith,
are rendered thoroughly impervious to moisture and non-electric.
It has been ascertained that paraffine in its natural hard state is such an
excellent non-conducting medium that the thin layer intervening between the
post and the insulator will effectually prevent the transmission of any electric
current, while the coating of paraffine on the exposed surfaces of the insulator
possesses so little affinity for moisture that such water as adheres to the
surface collects in the form of detached globules, the deposit of a con-
tinuous film of water, which frequently occurs on the surfaces of glass, rubber,
or other insulating materials, and which affords a medium for the escape of
electric currents being thus prevented. In applying this part of the Invention
to such insulators as are provided with a shield or outer casing of cast iron
the said shield is heated and immersed in molten paraffine which has the
effect of saturating the cast iron and preventing the moisture from penetrating
to the insulating material, and also preserves the iron from oxidation.
In carrying out the second part of the Invention, which relates to the
substitution of blown glass in place of cast or pressed glass, earthenware, or
other material in the construction of insulators, the improved material may be
used in a variety of ways, but it is preferred to employ it in the manner
described hereafter with reference to the third part of the Invention.

page_text: The Inventor has discovered, after lengthened and repeated experiments,
that blown glass is a much more perfect insulating medium than glass pressed.
into a mould, for the reason that the surface of pressed glass contains minute
fissures and roughnesses in which moisture and dust collect and permit the
escape of the electric currents, and that the inner surface of a blown glass
vessel being far smoother is much less liable to collect and retain moisture
than the outer surface of the same. By the substitution, therefore, of a blown
glass vessel for the pressed or moulded cup or cylinder beretofore employed
the wireholder is much more perfectly insulated, while the amount of glass
and consequently the weight of the insulator is reduced.
In carrying out the third part of the Invention, a wire holder of the usual
form (consisting of a rod flattened at one end and having two bent arms or
prongs at the other) is embedded in a vessel of blown glass, either by means
of sulphur or any other suitable cement. This vessel (which may be either
cylindrical or shaped like a flask or bottle) is then embedded in a shield or
casing or iron or earthenware by suspending it therein, and then pouring in
melted sulphur until the casing is nearly half full. While the whole is still
warm molten paraffine is poured into both the casing and the vessel and
after a short time poured out again, leaving a coating over the whole of the
interior. If it is found after the insulator has become cool that the sulphur
has absorbed the whole or greater portion of the paraffine, a sufficient quantity
of paraffine is again poured in to cover the surface of the sulphur and form a
ring or belt round the stein of the wire holder.
The fourth part of the Invention consists in preventing the damaging
effects of lightning upon telegraphic insulators by placing the points of the
arms or prongs of the wire holder nearer to the lower edge of the metallic
outer casing or shield than any other part of the holder is to any other part
of the said casing or shield.
It is well known that when the telegraph wires become surcharged with
the electric fluid, as during a storm, the latter will pass to the metallic casing
and thence to the earth by the shortest route, and if this route lies through
the glass or insulating medium (as in ordinary cases it does) the latter becomes
broken and the insulation destroyed, but by making the nearest route direct
from the points of the prongs to the outer casing the electric fluid passes.
that way, without forcing its way through the insulating material, and hence
no damage ensues.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Davies in the Great Seal Patent Office on the
29th January 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
DAVIES, of No. 1, Serle Street, Lincoln's Inn, in the County of Middlesex,
and No. 87, St. Vincent Street, in the City of Glasgow, Civil Engineer and
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of July, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirty-first year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
George Davies, Her special licence that I, the said George Davies, my
executors, administrators, and assigns, or such others as I, the said George
Davies, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
INSULATORS FOR TELEGRAPHIC WIRES," (a conmunication to me from abroad
by David Brooks, of Philadelphia, Pennsylvania, in the United States of
America, upon the condition (amongst others) that I, the said George Davies,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said George Davies, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, and on reference to the accompanying Drawing, that is
to say:-
This Invention consists, firstly, in the use of paraffine in the manner
described hereafter as an insulating medium in the construction of insulators
for telegraph wires.
Secondly, in the use of blown glass as an insulating medium in the
construction of such insulators.

page_text: Thirdly, in an improved construction of insulator, as fully described here-
after, which is more efficient and durable than those of the usual construction.
And, fourthly, in a means (described hereafter) of preventing the damaging
effects of lightning upon telegraph insulators.
The first part of the Invention, which relates to the use of paraffine as an
insulating medium, is applicable to the ordinary or most familiar form of
insulator, which consists of an earthenware or porcelain block having two
annular flanges or cups, with a socket in the interior for the reception of the
upper end of the post. This earthenware or porcelain insulator, while still
fresh from the kiln and retaining some degree of heat, is immersed in molten
paraffine and allowed to remain so until its pores have been completely filled
with that substance. When the insulator thus prepared is to be applied to a
wooden post or bracket that end of the latter to which the insulator is to be
attached is first heated to expel as much as possible of its moisture, and then
while still warm is dipped into molten paraffine with which it thus becomes
thoroughly saturated. By this means the various parts of the insulator, as
well as that portion of the post or bracket immediately in contact therewith,
are rendered thoroughly impervious to moisture and non-conductors of the
electric current.
It has been ascertained that paraffine in its natural hard state is such an
excellent non-conducting medium that the thin layers intervening between the
post and the insulator will effectually prevent the transmission of any electric
current, while the coating of paraffine on the exposed surfaces of the insulator
possesses so little affinity for moisture that such water as adheres to the
surface collects in the form of detached globules, the deposit of a continuous
film of water, which frequently occurs on the surfaces of glass, rubber, or
other insulating materials, and which affords a medium for the escape
of electric currents, being thus prevented. In applying this part of the
Invention to such insulators as are provided with a shield or outer casing
of cast iron the said shield is heated and immersed in molten paraffine,
which has the effect of saturating the cast iron and preventing the moisture
from penetrating to the insulating material, and also preserves the iron
from oxidation.
In carrying out the second part of the Invention, which relates to the
substitution of blown glass in place of cast or pressed glass, earthenware, or
other material in the construction of insulators, the improved material may
be used in a variety of ways, but it is preferred to employ it in the manner
described hereafter with reference to the third part of the Invention. The
Inventor has discovered, after lengthened and repeated experiments, that blown

page_text: glass is a much more perfect insulating medium than glass pressed into a
mould, for the reason that the surface of pressed glass contains minute fissures
and roughnesses in which moisture and dust collect and permit the escape of
the electric currents, and that the inner surface of a blown glass vessel being
far smoother is much less liable to collect and retain moisture than the outer
surface of the same. By the substitution, therefore, of a blown glass vessel for
the pressed or moulded cup or cylinder heretofore employed the wire holder is
much more perfectly insulated, while the amount of glass and consequently the
weight of the insulator is reduced.
In carrying out the third part of the Invention a wire holder of the usual
form (consisting of a rod flattened at one end and having two bent arms or
prongs at the other) is embedded in a vessel of blown glass, either by means
of sulphur or any other suitable cement. This vessel (which may be either
cylindrical or shaped like a flask or bottle) is then embedded in a shield or
casing of iron or earthenware by suspending it therein and then pouring in
melted sulphur until the casing is nearly half full. While the whole is still
warm molten paraffine is poured into both the casing and the vessel, and after
a short time poured out again, leaving a coating over the whole of the interior.
If it is found after the insulator has become cool that the sulphur has absorbed
the whole or greater portion of the paraffine a sufficient quantity of paraffine
is again poured in to cover the surface of the sulphur and form a ring or belt
round the stem of the wire holder.
The fourth part of the Invention consists in preventing the damaging effects
of lightning upon telegraph insulators by placing the points of the arms or
prongs of the wire holder nearer to the lower edge of the metallic outer
casing or shield than any other part of the holder is to any other part of the
said casing or shield. It is well known that when the telegraph wires
become surcharged with the electric fluid, as during a storm, the latter will pass
to the metallic casing and thence to the earth by the shortest route, and if
this route lies through the glass or insulating medium (as in ordinary cases it
does) the latter becomes broken or perforated and the insulation destroyed;
but by making the nearest route direct from the points of the prongs to the
outer casing the electric fluid passes that way, without forcing its way through
the insulating material and hence no damage ensues.
Such being the nature and object of the said Invention for "Improvements
in Insulators for Telegraphic Wires," I will now proceed to describe more in
detail the manner in which the same is to be or may be performed or carried
into practical effect, and in order that the same may be distinctly understood
I have annexed hereunto a Sheet of Drawings illustrative thereof, aud have

page_text: marked the same with Figures and letters of reference corresponding with
those in the following explanation thereof, that is to say :-
Figure 1 in the annexed Drawing represents a vertical section of the
ordinary or most familiar form of earthenware insulator, which consists of a
block a, a, having at the lower side two annular flanges or inverted cups b, b³,
the latter containing a socket c, c, for the reception of the upper end of a
post d, d. As previously described this earthenware insulator and the upper
end of the post are both saturated with paraffine whilst they are in a heated
state, so that all moisture is expelled and the paraffine penetrates into the
pores of both the earthenware and the wood. The earthenware should be
made as porous as practicable consistent with greatest strength, in order that
it may absorb as much paraffine as possible, and herein consists one of the
essential features of this Invention, as the practice in this country has hitherto
been to make the earthenware as perfect and impermeable as possible by
vitrifying or hard baking, and then to stop up any defects which may percbance
exist, whilst the object of the present Inventor on the contrary is to make
them in the first instance porous, in order that the paraffine may penetrate to
the greatest possible extent into the body of the material, and by thoroughly
filling all the pores prevent the possibility of the admission of any moisture
which is the greatest enemy to insulation. In the case of fracture in an
insulator thus prepared there is sufficient paraffine in the body to repel
moisture from entering the fracture, and in the event of the earthenware
being perforated by atmospheric charges the heat thereby evolved will melt
the paraffine, which will run into and fill up the hole and thus prevent any
moisture from entering the perforation.
Figures 2 and 3 in the annexed Drawing are vertical sections (taken at
right angles to each other) of an insulator, illustrating the second, third, and
fourth parts of this Invention. a, a, is the outer case or shield of metal (or
earthenware), the non-conducting properties of which will be greatly improved
by immersion whilst heated into molten paraffine, as previously described;
b, b, is a vessel of blown glass, and c, c, is the wire holder, which is provided
at one end with prongs or arnis d, d, for supporting the wires. The blown
glass vessel b, b, being placed mouth upwards the end of the wire holder c, c,
is inserted therein and embedded by pouring in molten sulphur or other
suitable cement e, e; this vessel is then embedded into the casing a, a, in a
similar manner and whilst the whole is still warm; the remaining space is
then filled with melted paraffine, and the insulator is then allowed to cool and
remain in that condition until the sulphur has shrunken and crystallized, when
the same is heated again to about 200 degrees Fahrenheit and kept at that

page_text: temperature (or such degree of heat as will keep the paraffine melted and not
melt the sulphur or cement) until the sulphur has absorbed its full capacity
of paraffine, when the surplus of paraffine is poured out leaving a sufficient
quantity to coat or cover the sulphur cement as at f, f. It will be observed
that the wire holder c, c, is inserted into the blown glass vessel b, b, to such
a depth that the ends of the prongs or arms d, d, are nearer to the lower
edge of the metallic casing a, a, than any other part of the wire holder is to
any other part of the said casing, the effect of which will be (as above
described) that in the event of the wires becoming surcharged with electric
fluid the excess will pass off direct to the outer casing without perforating the
insulating material.
Having now described the nature and object of the said Invention for
"Improvements in Insulators for Telegraphic Wires," together with the
manner in which the same is to be or may be performed or carried into
practical effect, I would remark in conclusion that I claim as the Invention
communicated to me by the aforesaid David Brooks,―
Firstly, the use or employment of paraffine as an insulating medium in
the construction of telegraphic insulators by immersing the parts therein
whilst in a heated state, substantially as and for the purposes herein-before
set forth.
Secondly, the use of blown glass as an insulating medium in the construc-
tion of such insulators.
Thirdly, the improved construction of telegraphic insulator herein-before
particularly described and shown at Figures 2 and 3 in the Drawings, or any
mere imitation or modification thereof.
And, fourthly, placing the points of the arms or prongs of the wire holder
of telegraphic insulators nearer to the lower edge of the metallic outer
casing or shield than any other part of the holder is to any other part of the
said casing or shield, for the purpose of preventing the deleterious effects of
lightning thereupon, substantially as before described.
In witness whereof I, the said George Davies, have hereunto set my
hand and seal, this Twenty-ninth day of January, in the year of our
Lord One thousand eight hundred and sixty-eight.
GEORGE DAVIES. (L.S.)