IMPROVEMENTS IN SCREW STEAM SHIPS AND PROPELLERS
Year: 1871

page_text: LETTERS PATENT to Robert Griffiths, of Rhual Issa, Mold, in the
County of Flint, Engineer, for the Invention of "IMPROVEMENTS IN
SCREW STEAM SHIPS AND PROPELLERS."
Sealed the 19th January 1872, and dated the 7th November 1871.
PROVISIONAL SPECIFICATION left by the said Robert Griffiths at the
Office of the Commissioners of Patents, with his Petition, on the
7th November 1871.
I, ROBERT GRIFFITHS, of Rhual Issa, Mold, in the County of Flint,
Engineer, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN SCREW STEAM SHIPS AND PROPELLERS," to be as follows:-
This Invention relates, first, to improvements in the construction of
steam ships for the purpose of applying the screw propeller at the bow
of the ship as well as at the stern, which improvements I effect in the
following manner :—
Firstly, at a suitable distance above the keel, and below the load water
line, I make openings in the bows of the ship on each side of the stem

page_text: post of sufficient size and continued far enough within the body to allow
the placing of a propeller of suitable construction. Behind this pro-
peller a second stem post is placed to carry the driving or screw shaft
and propeller, from this second stem post a second bow is formed of
suitable shape, joining the outer side of the ship, and forming with the
top, bottom, and other plates an opening on each side of the ship for the
discharge of the water from the propeller. At the bows of the ship I fix
two doors or plates for the purpose of closing the openings when the
propeller is not in use, and for the further purpose of steering the ship
when required by opening either door or flap, and leaving the other one
closed.
Another method of arranging the bows of the ship consists in cutting
away the bows under the water line and above the keel of a height a
little more than the diameter of the screw, carrying the bows to the
second stem post, and shaping them as required, leaving the space above
described open between the first and second stem post to allow the free
passage of the water to and from the propeller. The screw aperture in
the bow may be made straight or in a line with the keel to the after end
of screw, and leading down to the keel so as to discharge the water on
each side of the keel under the vessel.
The improvements in the construction of screw propellers according to
my Invention consists,―
First. In making two of the blades of a four-bladed screw propeller
smaller than the others, the difference of size depending on the require-
ments of the ship and engines.
Secondly. In applying a second screw propeller placed behind the
This screw is
propelling screw, and which I term a reactionary screw.
driven by the water forced backwards from the propelling screw, which
causes it to revolve, and the power obtained by the revolutions of this
screw is employed to aid the engine power (to which it is connected by
usual and well-known mechanical means) in propelling the vessel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Griffiths in the Great Seal Patent Office on
the 7th May 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
GRIFFITHS, of Rhual Issa, Mold, in the County of Flint, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of November, in the year
of our Lord One thousand eight hundred and seventy-one, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Griffiths, Her special licence that I,
the said Robert Griffiths, my executors, dministrators, and assigns, or
such others as I, the said Robert Griffiths, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN SCREW STEAM SHIPS AND PRO-
PELLERS," upon the condition (amongst others) that I, the said Robert
Griffiths, 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 imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Robert Griffiths, 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 :-
This Invention relates, first, to improvements in the construction of
steam ships for the purpose of applying the screw propellor at the bow
of the ship as well as at the stern, which improvements I effect in the
following manner, reference being had to the Drawing hereunto annexed,
in which Figure 1 represents a plan partly in section, and Figure 2 a
side view of the bow of a screw steam ship arranged and constructed in
accordance with the first part of my improvements.

page_text: At a suitable distance above the keel and below the low water line I
make openings a, a, in the bows of the ship on each side of the stem
post a¹ to admit the water to the propeller. The openings a, a, are of
sufficient size and are continued far enough within the body of the ship
to allow of the placing of a propeller of suitable construction. Behind
the propeller ba second stem post a³ is fixed so as to carry or support
the end of the driving or screw shaft b' and propeller b. From this
second stem post a second bow. c is formed of suitable shape joining the
outer side of the ship, and forming with the top, bottom, and other
plates an opening a³ on each side of the ship for the discharge of the
water from the propeller b. At the bows of the ship I mount two doors
or plates d, d, (as shown in the sectional plan view at Figure 3) on axes
for the purpose of closing the openings a, a. When the propeller is not
in use and for the further purpose of steering the ship when required a
bolt or other fastening d being employed to keep the doors closed when
required.
.
In Figures 1 and 2 only one door or flap d is shewn for acting as a
rudder for steering the vessel.
Another method of arranging the bows of the ship consists in cutting
away the bows under the water line and above the keel of a height a
little more than the diameter of the screw b, carrying the bows to the
second stem post a², and shaping them as required, leaving the space
above described open between the first and second stem post to allow the
free passage of the water to and from the propeller. The screw aperture
in the bow may be made straight or in a line with the keel to the after
end of the screw, and bending down to the keel so as to discharge the
water on each side of the keel under the vessel, as shown in Figures 4.
and ŏ of the Drawings hereunto annexed.
The improvements in the construction of screw propellers according to
my Invention consists,-
First. In making two of the blades of a four-bladed screw propeller
smaller than the others, the difference of size depending on the require-
ments of the ship and engines. The smaller or narrower blade I prefer
to make about half (more or less) of the propelling surface of the larger
blades. The larger bladess may be made to incline towards the vessel.
Secondly. My improvements in screw propellers consist in applying a
second screw propeller placed behind the propelling screw.
This screw

page_text: is driven by the water forced backwards from the propelling screw
which causes it to revolve; and the power obtained by the revolutions of
this additional screw is employed to aid the engine power, (to which it is
connected by usual and well-known mechanical means.
Having thus described the nature of my Invention, and the manner of
carrying the same into practice, I would have it understood that I do
not confine myself to the exact details herein described so long as the
novel features of my improvements are retained; but what I claim is,―
First. The improved arrangement and construction of the bows of
screw steam ships, and the application of the screw propeller thereto,
substantially in the manner and for the purpose herein-before described
and shewn in the Drawings hereunto annexed.
Secondly. I claim the arrangement and application of the doors or
plates d, d, for closing the openings a, a, or for steering the vessel,
substantially as herein-before described and shown in the accompanying
Drawings.
Thirdly. I claim the improved construction of screw propellers by
making some of the blades thereof smaller than the others, as herein-
before described.
Fourthly. I claim the application of a second screw propeller in
combination with the screw tunnel or channels a, a³, placed behind the
propelling screw, substantially in the manner herein-before described.
.
In witness whereof, I, the said Robert Griffiths, have hereunto set
my hand and seal, this Third day of May, in the year of our Lord
One thousand eight hundred and seventy-two.