IMPROVEMENTS IN INSULATORS FOR TELEGRAPH WIRES
Year: 1879

page_text: LETTERS PATENT to George Frederick Redfern, of the General Patent Office,
4, South Street, Finsbury, in the County of Middlesex, Patent Agent, for
the Invention of "IMPROVEMENTS IN INSULATORS FOR TELEGRAPH WIRES."
A communication from abroad by John Henry Bloomfield, of Concordia,
Entre Rios. in the Argentine Republic.
PROVISIONAL SPECIFICATION left by the said George Frederick Redfern
at the Office of the Commissioners of Patents on the 13th September
1879.
GEORGE FREDERICK REDFERN, of the General Patent Office, 4, South Street,
"IMPROVEMENTS
Finsbury, in the County of Middlesex, Patent Agent.
IN INSULATORS FOR TELEGRAPH WIRES." [A communication from abroad
by John Henry Bloomfield, of Concordia, Entre Rios, in the Argentine
Republic.]
The object of this Invention is to furnish improved insulators for telegraph wires,
which shall be simple in construction, easily applied and replaced, which will not
be liable to be broken by the breaking of the wire, which will not allow the wire
to run down or slacken for several poles when the wire breaks, and which will not
be liable to have the insulation of the wire destroyed by birds building nests of mud
around them, and the Invention consists in an insulator for telegraph wires, formed
of the insulator made of glass, porcelain, or glazed brown ware, perforated longitudi-
nally and countersunk at the lower end of the perforation, the screw made with a
round head having a square hole formed in it, the rubber bands, and the rubber
rings, as hereinafter described.
The insulator is designed to be made of glass, porcelain, or glazed brown ware,
with a convexed upper end, a concaved lower end, and a downwardly-projecting
cup-flange around its upper part, covering the part around which the wire
is to be fastened. The insulator is perforated longitudinally to receive a screw by
which it is secured to the lower side of the cross-bar attached to a pole.
The perforation is made a little larger than the body of the screw, so that the
insulator cannot be broken by the expansion of the said screw.
The lower end of the perforation through the insulator is countersunk to receive
the head of the screw, and the said head has a square hole or cavity formed in it,

page_text: in line with the axis of the screw, to receive a key for screwing it into and out of
the cross-bar.
Upon the body of the screw within the upper and lower parts of the perforation
through the insulator, are placed two rubber bands to fill up the space between the
screw and insulator, and keep the said insulator firm and steady.
Upon the body of the screw at its head is placed a rubber ring, which is made
a little smaller than the said head, and which when the screw is turned up into
place, is pressed into the countersink in the insulator and around the outer edge of
the screw-head, so as to cushion the said screw-head and keep it from coming in
contact with the said insulator.
Upon the screw at the upper end of the insulator is placed a rubber ring, which
when the said screw is turned up into place, is pressed into the upper end of the
space between the screw and insulator, and between the insulator and the cross-bar
so as to cushion the said insulator to the said cross-bar.
By this, construction the insulator is kept from contact with the screw and the
cross-bar, and the said screw is allowed to expand without breaking the insulator,
and to contract without loosening it.
The underside of the cross-bar is concaved to receive the upper end of the
insulator, to protect it from the weather.
With this construction, shonld an insulator be broken, a new one can be secured
in place with the same rubbers and screw that secured the old one, so that the line-
repairer will only have to carry a small key and a number of insulators, no nails,
hammer, screw-driver, screws, or the like being necessary.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Frederick Redfern in the Great Seal Patent Office on the 13th
March 1880.
GEORGE FREDERICK REDFERN, of the General Patent Office, 4, South Street,
Finsbury, in the County of Middlesex, Patent Agent. "IMPROVEMENTS IN
INSULATORS FOR TELEGRAPH WIRES." A communication from abroad by John
Henry Bloomfield, of Concordia, Entre Rios, in the Argentine Republic.
The object of this Invention is to furnish improved insulators for telegraph wires,
which shall be simple in construction, easily applied and replaced, which will not
be liable to be broken by the breaking of the wire, which will not allow the wire
to run down or slacken for several poles when the wire breaks, and which will
not be liable to have the insulation of the wire destroyed by birds building nests of
mud around them, and the Invention consists in an insulator for telegraph wires,
formed of the insulator made of glass, porcelain, or glazed brown, ware, perforated
longitudinally and countersunk at the lower end of the perforation; the screw made
with a round head having a square hole formed in it, the rubber bands, and the
rubber rings, as hereinafter fully described.
But to make the Invention communicated to me better understood, I will
proceed to describe the same by reference to the accompanying Drawing, in which
Figure 1 is a side view of one of the improved insulators, and Figure 2 a vertical
section of the same; Figures 3, 4 and 5, sections of slightly modified constructions
of insulators. Similar letters in all the Figures represent similar parts.
I will first describe the insulator shewn in Figures 1 and 2.
A represents the insulator which is designed to be made of glass, porcelain, or
glazed brown ware, with a convexed upper end, a concaved lower end, and two
downwardly projecting cup-flanges around its upper part, covering the part around
which the wire is to be fastened. The insulator A is perforated longitudinally to
receive the screw B, by which it is secured to the lower side of the cross-bar C
attached to a pole.
The perforation is made a little larger than the body of the screw B so that the
insulator cannot be broken by the expansion of the said screw.
The lower end of the perforation through the insulator is countersunk to receive
the head of the screw B, and the said head has a square hole or cavity a, formed in
it, in line with the axis of the screw, to receive a key b for screwing it into and
out of the cross-bar C.
Upon the body of the screw B, within the upper and lower parts of the
perforation through the insulator are placed two rubber bands D, to fill up the
space between the screw and insulator, and keep the said insulator firm and
steady.
Upon the body of the screw B, at its head is placed a rubber ring E, which is
made a little smaller than the said head, and which, when the screw is turned up
into place, is pressed into the countersink in the insulator A, and around the outer
edge of the said screw-head, so as to cushion the said screw-head and keep it from
coming in contact with the said insulator; H is a washer placed between the
head of the screw and the rubber E, to prevent the metal coming in contact with
the rubber.
Upon the screw B at the upper end of the insulator A, is placed a rubber ring F,
which when the said screw is turned up into place, is pressed into the upper end of
the space between the screw and insulator, and between the insulator and the cross-
bar C, so as to cushion the said insulator to the said cross-bar.
By this construction the insulator A is kept from contact with the screw B, and
the cross-bar C, and the said screw is allowed to expand without breaking the
insulator A, and to contract without loosening it.

page_text: The under side of the cross-bar C may be concaved to receive the upper end of
the insulator A, to protect it from the weather as shewn.
With this construction, should an insulator be broken, a new one can be secured
in place with the same rubbers and screw that secured the old one, so that the line
repairer will only have to carry a small key and a number of insulators, no nails,
hammers, screw-driver or screws being necessary.
In some cases the rubbers marked D, D, may be dispensed with with altogether,
using only the rubbers marked E, F, or the rubbers might be replaced with grommets
or rings of hemp, or leather saturated with paraffin, or rings of cork, or other suitable
elastic material, or the screw might be threaded down to the head with a slight
groove, and a strand of paraffined yarn wound in this groove, a little longer than
the insulator; then as the screw is driven home in the cross-arm, the strand of hemp
is forced back in the insulator, and prevents the insulator from coming in contact
with the screw.
Figure 3 shews an insulator similar to that shewn in Figures 1 and 2, as
herein before described, except that it is formed with only one downwardly projecting
cup flange.
In Figure 4 the upper ring F is replaced by a hemp grommet.
Figure 5 shews an insulator adapted to be fixed by means of a screw nut G, to
the spike I, the upper end of the screw B passing through the eye J of the
spike, a washer being placed between the upper rubber F and the spike; in this
arrangement the square hole in the head of the screw is not required.
Having thus described the Invention communicated to me, and the best means I
am acquainted with for carrying the same into effect, I wish it to be understood
that I do not confine myself to the precise details herein laid down and shewn in
the Drawing, as the same may be varied without departing from the peculiar
character of the Invention, but what is claimed and intended to be protected by
the herein in part recited Letters Patent is,-
The improvements in telegraph-insulators, substantially as herein before
described and represented in the accompanying Drawing, or any mere modification
thereof.
In witness whereof, I, the said George Frederick Redfern, have hereto set
my hand and seal, this Thirteenth day of March, in the year of our
Lord One thousand eight hundred and eightv.