AN IMPROVED METHOD OF MANUFACTURING CABLES, HAWSERS, OR SHROUD-LAID ROPES, AND OTHER CORDAGE ON A SCIENTIFIC PRINCIPLE
Year: 1799

page_text: TO ALL TO WHOM THESE. PRESENTS SHALL COME, I, JAMES
MITCHELL, of the Hamlet of Poplar and Black wall, in the County of Middlesex,
Rope Maker, send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Royal Letters Patent under the Great Seal of Great Britain, bearing
date at Westminster, on the Twenty-second day of July, in the thirty-ninth
year of His reign, give and grant unto me, the said James Mitchell, His
especial licence, full power, sole privilege, and authority, that I, the said
James Mitchell, during the term of fourteen years, therein expressed, should
and lawfully, might use, exercise, and vend, within that part of the King-
dom of Great Britain called England, the Dominion of Wales, and the
Town of Berwick-upon-Tweed, my Invention of "AN IMPROVED METHOD OF
MANUFACTURING CABLES, HAWSERS, OR SHROUD-LAID ROPES, AND OTHER CORDAGE ON
A SCIENTIFIC PRINCIPLE;" in which said Letters Patent there is contained a
proviso, obliging me, the said James Mitchell, by an instrument in writing
under my hand and seal, particularly to describe and ascertain the nature of
my said Invention, and in what manner the same is to be performed, and
cause the same to be inrolled in His Majesty's High Court of Chancery
within one calendar month next and immediately after the date of the said
Letters Patent, as by the said Letters Patent relation being thereunto had,
may more fully and at large appear.
And whereas it is well known that. cables, hawsers, and other cordage of.
magnitude, have been manufactured on erroneous principles; that in the

page_text: twist of a cable or the strand of a rope the external yarns circumscribing
large circles, and the internal small circles were productive of unequal bearings,
and consequently that a cable or large rope had many yarns that did not act
with the others. Nothing can exhibit this error more than crane ropes,
especially those used at stone wharfs where ponderous weights are to be
raised; that will try the strength, and also its property of resisting friction; that
these ropes, it is well known, always become ragged, the outside yarns break,
and exhibit a porcupine appearance. It is also well known that cables and
other large ropes for nautical uses have their external yarns broke and their
internal ones fresh and unstrained. How it has happened for ages past that
this error in a manufactory of so much consequence has continued, is not my
present enquiry; but this error will, I trust, be remedied in future by the present
discovery. It lays in the root or commencement of the process for manu-
facturing cordage, that is, in the cylindrical twist, or one-ninth part of a cable,
the cylindrical twist or one-third part of a hawser-laid rope, and the error
encreases as the girt of the rope increases, or as the component parts become
more numerous. To remedy this error is the object aimed at. Having
paid great attention to this subject, I have discovered to demonstration the
superiority of a different process, by subdividing the twists or cylindrical parts
of cables, hawsers, and ropes of large dimensions, and giving them a peculiar
turn so as to make them blend and unite, and also operating in such a
manner that the component parts act in spiral directions nearly approaching
to parrallels; and the rope when thus made acquires an increased tension from
the yarns all bearing together, and also combines every other property
required, such as resistance of fluids and friction, and that it acquires also
a more uniform elasticity. Such discovery being acted upon will become not
only of national utility, but universally so. Inducements have prompted me to
apply for Letters Patent that I may have such benefit as may be reasonably
expected to accrue from a discovery of so much importance. And that it
may be hereafter manifest to whomsoever may require information for that
purpose, the following directions, with an annexed plan, will exhibit the
process:-
NOW KNOW YE, that in compliance with said recited proviso, I, the
said James Mitchell, do hereby declare that the nature of.
my
said Invention,
and the manner in which the same is to be performed, is particularly
-described and ascertained as follows (that is to say):—
The yarns are to be spun and laid horizontally in parallels as usual, the full
length intended; then let the number required for the cylindrical twist or one-ninth
part of a cable, the cylindrical twist or one-third part of a hawser, or twist of any
'

page_text: other kind of rope, be divided into two, three, four, or more equal parts; turn the
subdivided twists at the extremities with the sun by means of a table wheel and
back frame, or otherwise, by means of the tackle board and sledge, until the
turn shall meet in the centre, then abate the turn at the ends, and render the
whole as nearly alike as possible, taking care that each one shall be a separate
and distinct column or twist; repeat the same in all the numbers of subdivided
twists required, which for distinction I name selvagee twists (selvagee twists
are of two sorts; the proper one consists of several rope yarns turned into a
circular form, and marled together, Fig. 3. The hand selvagee is the twist
or strand of a rope with the turn abated, and then knotted, Fig. 4); bring
together two, three, four, or more of these several selvagee twists (as may be
required for the strand of a rope or twist of a cable) at the extremities by
putting them on a forelock or neb hook at each end, turn these hooks with
the sun as before, and unite all the parts into a cylindrical form, acting with
press as usual, and reduce or contract this cylindrical twist or strand by
turning the hooks or cranks until it is shortened from one-eighth to one-sixth,
as the compression will be found to vary form rope made in the usual way,
and then the twist required will be obtained proceed with the remainder of the
process in the usual mode or way. When finished, it will be perceptible that
the yarns in the twists of large ropes, instead of circumscribing circles of
irrregular and various 'diameters, which is the cause of unequal bearings, will
by these subdivisions circumscribe small circles of more equality, that the
component parts or threads act together in lengthened spirals nearly ap
proaching parallels, and it will be visible and convincing that the rope
acquires sufficient hard or compression to resist fluids and friction, and on
trial will be found with encreased tension or strength, and a more uniform
elasticity, and this process applys to white as well as tarred ropes, as all
descriptions of cordage is to be made in this manner, with or without tar.
This manufacture is strikingly distinguished from every other mode yet made
use of or invented. Hitherto cable-laid cordage has been composed of nine
cylindrical twists, and hawser-laid cordage composed of three cylindrical
twists (four strand ropes excepted, which can also be made on this principle);
by the present Invention cable laid cordage is composed of eighteen, twenty-
seven, thirty-six, forty-five, fifty-four, sixty-three, seventy-two cylindrical parts
or twists, which, for distinction, I name selvagee twists (from their resem-
blance to a hand selvagee), or any number of them multiplied be nine; and
hawser-laid cordage is composed of six, nine, twelve, fifteen, eighteen; twenty-
one cylindrical parts or twists, called also selvagee twists, or any number
multiplied by three. The turn in the selvagee twists is peculiar to this

page_text: manufacture, acting with each other instead of reversing, so as to 'make
them bed and unite; whilst the customi hath thitherto been 1to reverse the
turn in every part of the process. These cylindrical twists' are not procured
by the act of winding, or so placed as to deprive them' 'of their full reactive
power, without which rope of every description must be defective; but they
retain their full reaction, unite and blend the parts so as to resist fluids,istánd
friction, acquires a more uniform elasticity, and makes the whole of its
component parts have equal bearings, or very nearly so, and it.can be demon-
strated that any one of less girt or circumference is equal in strength to orie
made in the common way of an encreased girt or circumference. The..equal
bearings may be shewn by 'the selvagee twists, which cannot be disturbed, by
any subsequent part of the process throughout the whole operation, as may
be made to appear by taking three, four, or more parts (that compose the
whole twist) in the hand, and making therewith a circular movement; or by
restoring the twist to parallels, as when the operation first commenced. On
the whole, the present improvement is manifest, on view, both to the scientific
world and every beholder. The annexed Drawing will illustrate the process;
and exhibit the cable in all its parts. Fig. 1, the selvagee twists b, b, b, b, b, b;
are represented as taken from the table wheel and back frame,. and stretched
in parallels with a temporary fastening between the posts a, a.. Fig. 2, A, the
cable. B, B, B, the cable strands; 'c, c, c, the twist which..compose the
strand; D, D, D; the selvagee twists' or subdivisions which are united in that
twist. Fig. 3 represents a marled selvagee, used for setting up rigging, &c. &c.
Fig. 4 represents a hand selvagee, which is the strand of a rope with the turn
abated and then knotted, and used for the same purpose as the marled selvagee:
These selvagees are remarkable for their great strength, which is the reason
why rope made on the new principle is called selvagee cordage.
In witness whereof, I, the said. James Mitchell, have hereunto set my
hand and seal, this Ninth day of August, in the thirty-ninth year of the
reign of our Sovereign Lord George the Third, by the grace of God,
of Great Britain, France, and Ireland, King, Defender of the Faith;
and so forth, and in the year of our Lord One thousand seven hundred
and ninety-nine.
'

page_text: AND BE IT REMEMBERED, that on the same Ninth day of August, in
the year above mentioned, the aforesaid James Mitchell came before our Lord
the King in His Chancery, and acknowledged the Specification aforesaid, and
all and every thing therein contained, in form above written. And also the
Specification aforesaid was stamped according to the tenor of the Statute in
that case made and provided.
Inrolled the same Ninth day of August, in the year above written.