IMPROVEMENTS IN THE CONSTRUCTION OF SHIPS TO ADAPT THEM FOR AUXILIARY SCREW PROPELLERS
Year: 1869

page_text: LETTERS PATENT to James Jack, of Liverpool, in the County of
Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF SHIPS TO ADAPT THEM FOR AUXILIARY SCREW PROPELLERS."
Sealed the 18th September 1869, and dated the 19th March 1869.
PROVISIONAL SPECIFICATION left by the said James Jack at the
Office of the Commissioners of Patents, with his Petition, on the
19th March 1869.
I, JAMES JACK, of Liverpool, in the County of Lancaster, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN.
THE CONSTRUCTION OF SHIPS TO ADAPT THEM FOR AUXILIARY SCREW PROPELLERS,"
to be as follows:-
It has been found that auxiliary screw propellers as at present applied
to sailing ships do not act effectively in consequence of the water
being impeded in its entrance to the screw, and also because the ship

page_text: drags water in her wake about and near the boss of the said propeller.
To remedy this defect, and to provide means by which when a ship is
under canvas an unbroken skin and ordinary lines can be secured is
the object of my present improvements. For this purpose I construct
that part of the ship immediately forward of the screw propeller of a form
tapering towards the screw; by so doing a free entrance for water is
provided; and to close in the said tapered portion of the ship and the
opening in which the propeller works I employ a single or double slide
or shutter operated from the deck. When the ship is under steam the
said slide or shutter is raised.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Jack in the Great Scal Patent Office on
the 18th September 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
JACK, of Liverpool, in the County of Lancaster, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of March, in the
year of our Lord One thousand eight hundred and sixty-nine, in the
thirty-second year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said James Jack, Her special
license that I, the said James Jack, my executors, administrators,
and assigns, or such others as I, the said James Jack, 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 THE CONSTRUCTION OF SHIPS, TO ADAPT THEM FOR AUXILIARY SCREW PRO-
PELLERS," upon the condition (amongst others) that I, the said James
Jack, 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

page_text: 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 James Jack, do hereby declaro
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, reference being had to the accompanying
Sheet of illustrative Drawings, and to the figures and letters thereon,
that is to say:-
It has been found that auxiliary screw propellers as at present applied
to sailing ships do not act efficiently in consequence of the water being
impeded in its entrance to the screw, and also because the ship drags
water in her wake about and near the boss of the said propeller. To
remedy these defects, and to provide means by which when a ship is
under canvas an unbroken skin and ordinary lines can be secured is
the object of my present improvements. For this purpose I construct
that part of the ship immediately forward of the screw propeller of a
form tapering towards the screw; by so doing a free entrance for water
is provided; and to close in the said tapered portion of the ship and
the opening in which the propeller works I employ a single or double
slide or shutter operated from the deck. When the ship is under
steam the said slide or shutter is raised, and when under sail, it is

page_text: Figs. 6, 7, 8, and 9; i, opening wherein the screw propeller works; j,
strong slide or shutter let down from the deck, in and through the opening
k (shewn on Fig. 5) into the position shewn on Fig. 4 when the propeller
is not at work, and raised into the position shewn on Fig. 1 when the
propeller is at work. The object in lowering the said slide or shutter j
when the propeller is not at work is to close the opening i and pro-
vide a ship with a so-called unbroken skin, such ship having ordinary
lines and no more than ordinary width near the stern post in the run.
The advantages resulting from closing the said opening securely are
well known to mariners, but I would have it distinctly known that
according to my improvements it is absolutely requisite that the outer
plates or skin of the said slide or shutter, whether such slide or shutter
is made in one or more pieces, should be strongly supported at the back:
I prefer the arrangement and combination of parts of wrought iron with
angular guide surfaces at k and rudder post guide pieces at 7, shown in
and by Figs. 1 to 9 inclusive.
Fig. 10, Sheet B, is a modification, showing how the skin plates
a of the ship are made to overlap the strong slide or shutter ;
6', bulkhead; c', inner stern post; d, outer or rudder post; e³, pro-
peller shaft; f, auxiliary screw propeller; g', tapering part of the
ship.
Figs. 11 and 12, Sheet B, are also horizontal sections of the stern
portion of an iron ship, the tapering portion of which is made of cast
iron. a³, skin plates; b, bulkhead; c², innor stern post; d, outer or
rudder post; es, propeller shaft; f, propeller; g³, tapering part
constructed as above mentioned of cast iron. The said cast iron is
secured by bolts m³ to the bulkhead &; enclosing slide or shutter.
Having now described the nature of my said Invention and par-
ticularized the same, I would have it distinctly understood that my
said improvements are not confined to iron ships now being or hereafter
to be constructed, as they can be applied as well to wooden and other
ships as to iron ships already in use, neither do I confine myself to the
exact details of parts shewn on the Drawings; what I claim is,
constructing ships or navigable vessels at that part immediately forward
of the propeller of a form tapering aft for the purpose set forth, and
providing such ships or navigable vessels with a strong supported slide
or shutter, for the purpose set forth, all substantially by the practicable

page_text: means illustrated on the accompanying Sheets of Drawings, and described
herein.
In witness whereof, I, the said James Jack, have hereunto set my
hand and seal, this Sixteenth day of September, in the year
of our Lord One thousand eight hundred and sixty-nine.
In the presence of
JOHN T. KING,
Patent Agent,
Liverpool.
JAMES JACK. (L.S.)