AN IMPROVED METHOD OF INSULATING AND MAINTAINING THE INSULATION OF UNDERGROUND TELEGRAPHIC WIRES
Year: 1873

page_text: LETTERS. PATENT to Matthew Gray, of Blackheath, in the County of
Kent, Engineer, for the Invention of "AN IMPROVED METHOD OF
INSULATING AND MAINTAINING THE INSULATION OF UNDERGROUND TELEGRAPHIC
WIRES."
Sealed the 2nd April 1874, and dated the 26th November 1873.
PROVISIONAL SPECIFICATION left by the said Matthew Gray at the
Office of the Commissioners of Patents, with his. Petition, on the
26th November 1873.
;
I, MATTHEW. GRAY, of Blackheath, in the County, of Kent, Engineer,
do hereby declare the nature of the said Invention for. "AN IMPROVED
METHOD OF INSULATING AND MAINTAINING THE INSULATION OF UNDERGROUND
TELEGRAPHIC WIRES," to be as follows:
The object of this Invention is to render naked or uncovered wires ·
available for conducting currents of electricity under roads and
ways.
j

page_text: For this purpose I support the wires at tension by leading them through
perforated blocks or discs of any suitable insulating material such as
ebonite or glazed porcelain, and these blocks or discs I fix at suitable
intervals in a continuous length of pipes or their equivalent which I
make as far as practicable air-tight. To prevent the wires thus encased
becoming damp or to remove moisture therefrom, the presence of which
would serve to destroy their insulation, I propose to pass dry air through
the enclosing pipes which will carry off any moisture contained therein
and restore the insulation.
.
Before the air is admitted to the pipes it should be made to part with
its moisture. This may be effected by passing it over quicklime or
submitting it to the action of sulphuric acid and pumice stone, or any
other equivalent absorbent of water.
.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Matthew Gray in the Great. Seal Patent Office
on the 26th May 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MATTHEW
GRAY, of Blackheath, in the County of Kent, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of November, in the
year of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Matthew Gray, Her special
licence that I, the said Matthew Gray, my executors, administrators,
and assigns, or such others as I, the said Matthew Gray, 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 "AN IMPROVED

page_text: METHOD OF INSULATING AND MAINTAINING THE INSULATION OF UNDERGROUND
TELEGRAPHIC WIRES," upon the condition (amongst others) that I, the
said Matthew Gray, 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 Matthew Gray, do hereby declare
the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawing hereunto
annexed, and to the letters and figures marked thereon (that is to
say):
The object of this Invention is to render naked or uncovered wires
available for conducting currents of electricity under roads and ways.,
For this purpose I support the wires at tension by leading them through
perforated blocks or discs of any suitable insulating material, such as.
ebonite or glazed porcelain, and these blocks or discs I fix at suitable
intervals in a continuous length of pipes or their equivalent, which I
make as far as practicable air-tight. To prevent the wires thus encased
becoming damp or to remove moisture therefrom, the presence of which
would serve to destroy their insulation, I propose to pass dry air through
the enclosing pipes which will carry off any moisture contained therein
and restore the insulation.
The manner in which I propose to carry out my Invention is
illustrated in several views in the accompanying Drawing.
Fig. 1 represents in longitudinal vertical section a portion of an
underground line of telegraphic communication composed of naked-
wires; Fig. 2 is a sectional plan of the same taken in the line 1, 2, of
Fig. 1 and Fig. 3 is a transverse section taken in the line 3.4 of

page_text: adjacent pipe. Interposed between these coupled pipes at any con-
venient points along the line of telegraphic communication are broad
shallow chambers B, in which the wires are joined up. These chambers
are made of a breadth say of three diameters of the pipe with which
they are connected, and are conveniently cast with sockets C to receive
the ends of the pipes A, and with internal ribs or flanges to support
diaphragms D, D, of india-rubber or porcelain for the purpose to be
presently explained. The chambers B are closed by a cover B', which
is secured in place by bolts and nuts. Fitting into the necks of the
sockets C are circular flanged discs of ebonite, glazed porcelain, or other
suitable non-conductor E formed, with tubular lateral extensions on
opposite sides thereof. These discs are pierced with holes to allow of a
free circulation of air through the pipes. The tubular extensions form
insulating supports for the several wires F, and thus when drawn to
tension the lengths of wires contained in the pipes will be effectually
insulated. For joining up the lengths of wires they are led through the
pierced diaphragms D, D, which serve as guide plates, disposing the
wires laterally so as to render them easily accessible to the workman.
The ends of the wires thus presented to each other may be coupled up
in the usual manner, or any one or more of the wires may be led out
from the chamber B. and brought into. connection with the local tele-
graphic instrument as indicated by the red lines in Fig. 2. . Suitable.
precautions must be used to ensure the insulation of the naked wire or
wires led off to the instrument.
I may remark that the air circulating in the pipes may, if thought
desirable before its admission to the pipes, be made to part with its
moisture. This may be effected by passing it over quicklime or sub-
mitting it to the action of sulphuric acid and pumice stone, or any other
equivalent absorbent of water.
By the above described means a great economy will be effected in the
laying down of underground lines of telegraphic wires.
Having now set forth the nature of my Invention of "An Improved
Method of Insulating and Maintaining the Insulation of Underground
Telegraphic Wires," and explained the manner of carrying the same
into effect, I wish it to be understood that under the above in part
nocited Lottona Patent I claim insulating undonaround taleomanbis mines

page_text: and maintaining their insulation in the manner and for the purpose
above described.
In witness whereof, I, the said Matthew Gray, have hereunto set
my hand and seal, the Twenty-third day of May, in the year of
our Lord One thousand eight hundred and seventy-four.
MATTHEW GRAY. (L.S.)