IMPROVE- MENTS IN THE MANUFACTURE OF TELEGRAPH CABLES, AND IN COVERING TELE- T CAVDRAMADA TY COMPANYS THEREFOR "
Year: 1873

page_text: LETTERS PATENT to William Hooper, of 31, Lombard Street, in the
City of London, and John Macmillan Dunlop, of Windermere,
in the County of Westmoreland, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OF TELEGRAPH CABLES, AND IN COVERING TELE-
T
CAVDRAMADA
TY COMPANYS THEREFOR
"
PROVISIONAL SPECIFICATION left by the said William Hooper and
John Macmillan Dunlop at the Office of the Commissioners of
Patents, with their Petition, on the 4th December 1873.
We, WILLIAM HOOPER, of 31, Lombard Street, in the City of
London, and JOHN MACMILLAN DUNLOP, of Windermere, in the County
of Westmoreland, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF TELEGRAPH CABLES, AND
COVERING TELEGRAPH CONDUCTORS, AND IN COMPOUNDS THEREFOR," to be as
follows:-
:-
IN
The main object of this Invention is the preparation of a compound
suitable for covering the conductors of telegraph cables to be applied

page_text: as an insular either directly to the conductor or over another insulator
which we prefer to be of india-rubber, and such compound is suitable
also for imbedding the fibrous yarns, and for covering the wires with
which the cable core is surrounded, and it is also suitable to be applied
together with tape or with yarns or otherwise to telegraph wires to be
used on land, in tunnels, and many other places in which a covered
wire is required.
The materials which we employ are inexpensive, and the new com-
pound which we produce is a good insulator; it is unchanged by water,
it is tough, and does not readily crack when bent, and (which is a point ]
of great importance) it is free from naphtha or other such like volatile
material likely to affect prejudically the high insulating properties of
india-rubber, as wood tar or pitch always does when used with an
insulator of india-rubber in telegraph cables.
We employ the soft tar obtained from the distillation of cotton seed 1
oil, or it may be the "foots" of this or other vegetable drying oil;
this soft tar or oil we oxidise by treating it whilst hot with nitric
acid. The product we mix with the hard pitch obtained from the
distillation of cotton seed oil or other vegetable drying oil we so
obtain the compound which we require. It becomes sufficiently fluid
for use at a temperature somewhat exceeding 300 degrees Fahrenheit;
we also saturate the fibrous yarns employed in telegraph cables with
the soft pitch obtained by the distillation of cotton seed oil or other
vegetable drying oil; this treatment renders the yarns non-absorbent.
SPECIFICATION in pursuance of the conditions of the Letters Patent, 25
filed by the said William Hooper and John Macmillan Dunlop in
the Great Seal Patent Office on the 4th June 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
HOOPER, of 31, Lombard Street, in the City of London, and JOHN
MACMILLAN DUNLOP, of Windermere, in the County of Westmoreland, 30
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her

page_text: 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 us, the said William Hooper and John
Macmillan Dunlop, Her special license that we, the said William
Hooper and John Macmillan Dunlop, our executors, administrators,
and assigns, or such others as we, the said William Hooper and John
Macmillan Dunlop, our 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 THE MANUFACTURE OF TELEGRAPH CABLES,
AND IN COVERING TELEGRAPH CONDUCTORS, AND IN COMPOUNDS THEREFOR," upon
the condition (amongst others) that we, the said William Hooper and
John Macmillan Dunlop, our executors or administrators, by an instru-
ment in writing under our or their hands and seals, or under the hand
and seal of one of us or them, 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 we, the said William Hooper and John Mac-
millan Dunlop, do hereby declare the nature of the said Invention, and
in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement thereof, that is to
say:-
The main object of the Invention is the preparation of a compound
suitable for covering the conductors of telegraph cables. to be applied
as an insulator either directly to the conductor or over another insulator.
which we prefer to be of india-rubber, and such compound is suitable
also for imbedding the fibrous yarns and for covering the wires with
which the cable corc is surrounded, and it is also suitable to be applied
together with tape or with yarns or otherwise to telegraph wires to be
used on land, in tunnels, and many other places in which a covered
wire is required.
The materials which we employ are inexpensive, and the new com-
pound which we produce is a good insulator; it is unchanged by water,
it may be made tough and so as not readily to crack when bent, and

page_text: (which is a point of great importance) it is free from napotna or on
such like volatile material likely to effect prejudicially the high in-
sulating properties of india-rubber, as wood tar or pitch always do when
used with an insulator of india-rubber in telegraph cables.
We employ the soft tar or pitch obtained from the distillation of
cotton seed oil, or it may be the "foots" of this or other vegetable
drying oil; this soft tar, or pitch, or oil we oxidise by treating it
whilst hot with nitric acid; this we do by heating the material to a
temperature of about 350° Fahrenheit, and then stirring into it gradually
strong nitric acid until it thickens, about 10 or 12 pounds of acid to
the hundredweight of the material will usually be found sufficient,
but the thickening of the mixture indicates when sufficient acid has
been added. The product somewhat resembles india-rubber in its general
appearance; it is black and elastic, but it is decidedly softer than
india-rubber. Soft pitch of cotton seed oil of the consistency of treacle
is the material we prefer to treat as above stated. The product we
mix with the hard pitch obtained from the distillation of cotton seed
oil we so obtain the compound which we require; we first melt the
material which has been treated with acid in an iron pot by fire
heat with about one-seventh of its weight of soft pitch, and when
melted we add twice its weight of hard pitch, preferring that from
the distillation of cotton seed oil; this hard pitch is of a brittle nature
and breaks with a vitreous fracture.
The compound may be made harder or softer by varying the pro-
portions. It becomes sufficiently fluid for use at a temperature somewhat
exceeding 300 degrees Fahrenheit.
ek
The way in which to employ this compound is as an outer covering
around a Hooper" core, that is to say, a conductor already insulated
with india-rubber and vulcanised india-rubber. The core is run through
the melted compound, and so are the strands or yarns of fibrous material
which are laid around the core to form the cable, either with or without
protecting wires.
In making the compound we sometimes substitute for the soft pitch
which has been changed by means of nitric acid, a material which
closely resembles this product, and which we obtain in the English
market under the name of "oudroic." This substance is obtained as
a byc product from the distillation of matters containing stearine, and

page_text: it chiefly comes to this country from Holland. This "oudroic" if not
identical with the product of the action of nitric acid on soft pitch
of cotton seed oil resembles it so closely that we are able to employ it
in all respects in a similar manner.
Having thus described the nature of our said Invention, and the
manner of performing the same, we would have it understood that
we claim, the manufacture and use in the construction of telegraph
cables, and in covering telegraph conductors, of the compounds sub-
stantially as described.
In witness whereof, we, the said William Hooper and John Mac-
millan Dunlop, have hereunto set our hands and scals, this Third
day of June, in the year of our Lord One thousand eight hundred
and seventy-four.
WILLIAM HOOPER. (L.S.)
JOHN M. DUNLOP.
(L.S.)