AN IMPROVED SCREW PROPELLER FOR SHIPS
Year: 1869

page_text: LETTERS PATENT to Charles. Moore, of Sketty, near Swansea, in the
County of Glamorgan, Commission Agent, for the Invention of "AN
IMPROVED SCREW PROPELLER FOR SHIPS."
Sealed the 2nd November 1869, and dated the 5th May 1869.
PROVISIONAL SPECIFICATION left by the said Charles Moore, at the
Office of the Commissioners of Patents, with his Petition, on
the 5th May 1869.
I, CHARLES MOORE, of Sketty, near Swansea, in the County of
Glamorgan, Commission Agent, do hereby declare the nature of the
said Invention for "AN IMPROVED SCREW PROPELLER POR SHIPS," to be as
follows:-
The propeller consists of a double threaded screw of half a convolution,
which is brought to a body at the shaft in the centre of the dead wood.
The leading edges of both threads or blades are formed in such a way
that they join in the centre at both ends of the screw shaft, and form
a curved line curling in opposite directions. The threads or blades
themselves are concave and convex on each surface, balance each
other, and are shaped in such a manner that the chief propelling

page_text: surface of each falls towards the line of junction, and that the streams
of water thrown off by the propeller diverge, thereby preventing
churning of the water near the centre of motion, and always leaving
the rudder in quiet water. Experience has taught that the leading
edge of a screw is that which most affects the steerage of a ship and causes
the vibration. I have proved that by the peculiar shape of the threads
or blades of my propeller, leaving the rudder always in quiet water,
it not only assists the steerage, but, as the leading edges of the threads
are constructed so that they enter the water more quietly, and as the
chief propelling surfaces of the blades fall towards the centre, it will
lessen or take away entirely the vibration of the shaft, (and as the
leading edges form one closed, curved, and curled line it will not be
subject to breakage, and fouling materials, and will render its force
or propelling power equal in going by ahead or astern.
The pro-
portion between the diameter and the pitch of the screw in my pro-
peller is such that I consider it will economise the power applied to
the driving of the propeller.) The direction of the blades obviates as
much as possible the resistance offered to the water when a ship is
under canvass, and it is therefore not required to disconnect the pro-
peller or raise it out of the water when it is not used to facilitate a
ship's progress.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Moore in the Great Seal Patent Office
on the 4th November 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
MOORE, of Sketty, near Swansea, in the County of Glamorgan, Commis-
sion Agent, &c., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the fifth day of May, 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 successors, give and
grant unto me, the said Charles Moore, Her special licence that I,
the said Charles Moore, my executors, administrators, and assigns,
or such others as I, the said Charles Moore, my executors, adminis-
trators, and assigns, should at any time agree with, and no others,

page_text: 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 "PROPELLING SHIPS
OR VESSELS," upon the condition (amongst others) that I, the said
Charles Moore, 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 Charles Moore, 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 :-
My Invention consists in the peculiar formation and action of a
double threaded screw propeller for ships of half a convolution, which
is brought to a body at the propelling shaft between the foreward and
aft sternpost. The leading edges of both threads or blades are formed
to join in the centre at both ends of the said shaft, and form a closed
curved line curling in opposite directions. The threads or blades them-
selves are concave and convex on each surface, balance each other, and
are shaped in such a manner that the chief propelling surface of each
falls towards the lines of junction, and that the streams of water thrown
off by the propeller diverge, thereby preventing churning of the water
near the centre of motion, and always leaving the rudder in compara-
tively quiet water. Experience has taught that the leading edge of a
screw is that which most affects the steerage of a ship or vessel and
causes vibration. I have found that by the peculiar shape or form of
the threads or blades of my propeller, leaving the rudder in nearly
quiet water, it not only assists the steerage, but, as the leading edges
of the threads or blades are so constructed that they enter and leave the
water more quietly than those of most screw propellers, and as the
chief propelling surfaces of the threads or blades fall towards the
centre, and are considerably greater than those of single screw propellers
generally, its pressure is more equalized, and having from its peculiar
shape a continuous pressure on the water, my propeller may consequently

page_text: be expected to lessen or nearly take away the vibration at the shaft.
The direction of the blades obviates as much as possible the resistance
offered to the water when a ship is under canvass, it is therefore not]
required to disconnect or raise my propeller out of the water (when
it is not in motion) to facilitate a ship's progress. It is less liable to
breakage and to fouling materials. than other propellers, as the leading
edges form one closed curved and curled line, and its propelling power
is equal in going ahead or astern. The proportion between the diameter
and the pitch of the screw of my propeller is such that I. consider it
This
will economise power applied to the driving of the propeller.
peculiar shape of the blades or threads which is to be seen in the
attached Drawings No. 1 and No. 2., No. 1 being an end view and No.
2 a side view, I claim as my Invention, including any other improve-
ments which the propeller contains not herein described, or which I
may find necessary to make.
My propeller is a solid body without part or parts.
Having now described the particular nature of my said Invention,
and the manner in which the same may be used or carried into effect,.
I would have it understood, that I do not confine or restrict myself to
the several details or arrangements herein described, as variations may
be made therefrom without deviating or departing from the principle or
main features of my said Invention.
In witness whereof, I, the said Charles Moore, have hereunto set
my hand and seal, this Second day of November, in the year of
our Lord One thousand eight hundred and sixty-nine.
CHARLES MOORE (L.S.)
CHARLES MOORE
(L.S.)