AN IMPROVEMENT IN THE CONSTRUCTION OF SCREW PROPELLERS
Year: 1862

page_text: LETTERS PATENT to William Joseph Curtis, of Tufnell Park Road,
Holloway, in the County of Middlesex, Civil Engineer, for the Inven-
tion of "AN IMPROVEMENT IN THE CONSTRUCTION OF SCREW PROPELLERS."
Sealed the 9th December 1862, and dated the 16th June 1862...
PROVISIONAL SPECIFICATION left by the said William Joseph Curtis
at the Office of the Commissioners of Patents, with his Petition, on the
16th June 1862.
I, WILLIAM JOSEPH CURTIS, of Tufnell Park Road, Holloway, in the County
of Middlesex, Civil Engineer, do hereby declare the nature of the said
Invention for "AN IMPROVEMENT IN THE CONSTRUCTION OF SCREW PROPELLERS,"
to be as follows:-
The object of this Invention is to render the propelling screw of steam. ships
available in combination with the rudder for steering such vessels.. Hitherto
the difficulty of carrying out this object has been insuperable, from the
necessity for providing such a connection between the propeller and its driving.
shaft as would resist the great strain to which it must be exposed.. I now.
propose to mount the propeller on the extremity of the driving shaft in.such a
manner that it will be free to move with the rudder without its power of
rotation being in any way interfered with. The coupling employed may be
a ball-and-socket joint fitted with a key, or a universal joint. enclosed, or

page_text: surrounded by the boss of the screw propeller. Projecting rearwards from the
boss in a line with the axis of the driving shaft is a trunnion, which has its
bearing in a swing frame that forms a portion of the rudder. The weight of
the propeller, and the strain to which it will be subjected, is sustained entirely
by the driving shaft, and the position of the propeller is such that the axis of
the rudder is coincident with the central line of the propeller. When,
therefore, the rudder is moved by the steersman, the propeller will swing
round with it, and by acting at an angle to the propeller shaft it will materially
assist the steering of the vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Joseph Curtis in the Great Seal Patent Office
on the 16th December 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, WILLIAM
JOSEPH CURTIS, of Tufnell Park Road, Holloway, in the County of Middlesex,
Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixteenth day of June, in the year of our Lord One
thousand eight hundred and sixty-two, in the twenty-fifth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
William Joseph Curtis, Her special license that I, the said William Joseph
Curtis, my executors, administrators, and assigns, or such others as I,
the said William Joseph Curtis, 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
"AN IMPROVEMENT IN THE CONSTRUCTION OF SCREW PROPELLERS," upon the
condition (amongst others) that I, the said William Joseph Curtis, by an
instrument in writing under my hand and, seal, 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 William Joseph Curtis, 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

page_text: following statement, reference being had to the Drawing hereunto annexed,
and to the letters and figures marked thereon (that is to say):
The object of this Invention is to render the propelling screw of steam ships
available in combination with the rudder, or even without a rudder, for steer-
ing such vessels. Hitherto the difficulty of carrying out this object has been
insuperable, from the necessity for providing such a connection between the
propeller and its driving shaft as would resist the great strain to which it
must be exposed. I now propose to mount the propeller on the extremity of
the driving shaft, in such a manner that it will be free to move with the
rudder without its power of rotation being in any way interfered with.
In the accompanying, Drawing, Fig. 1 shews in sectional elevation a
Griffith's propeller mounted according to my Invention, whereby at the will
of 'the steersman it may be placed and temporarily retained at an angle to the
course of the ship, and thus by its propelling power cause the ship to swing
round to any given point of the compass; Fig. 2 is a front elevation of the
propeller, the propeller shaft being in section,; Fig. 3 is a sectional plan view,
taken in the line 1, 2, of Fig. 1; and Fig. 4 is a sectional plan view taken in
the line 3, 4, of Fig. 1.
The propeller is formed with a hollow boss A to receive a compound joint
coupling, which connects the boss with the driving shaft B of the screw
propeller. On the outer or coupling end of this shaft B is forged a block B',
which is bored to receive a short horizontal cross shaft B². The ends of this
cross shaft form trunnions, which enter sockets made to receive them in a
strong wrought-iron or other metal ring C. This ring is inserted in the hollow
propeller boss A, and it is retained in position therein by means of the stem D
of the propeller blades E. Holes are bored in the ring at right angles to the
trunnion sockets to receive the stem D. The propeller blades are made with
a broad flange, in order to bear against and bed upon a flat surface formed ou
the hollow boss. A coarse screw is cut on an enlargement of the propeller
stenis, and the boss is suitably tapped to receive the screws. When, therefore,
the blades are brought into position, their stems effectually secure the boss to
the propeller shaft, leaving, however, the propeller free to turn, as on a hinge
joint. Projecting rearwards from the boss A is a trunnion A', which has its
hearing in a swing frame F. This frame, when constructed as shewn in the
Drawing, and covered with plates of iron, forms a rudder for assisting in the
steering of the ship. To ensure the propeller turning freely on its compound
joint, it is requisite that the centres of the pintles of the rudder and of the
compound joint should be so arranged as to lie in the same vertical plane, as
indicated by the red line, Fig. 1. It will be seen that the weight of the

page_text: propeller and the strain to which it will be subjected is sustained entirely by
the driving shaft, the trunnion projecting. from the rear of the boss acting
simply as a guiding arm for changing the position of the propeller with respect
to the line of progress of the ship. From the above description it will be
understood that when the rudder is moved by the steersman the propeller will
swing round with it without its rotary motion being affected by the change of
position, and that by acting at an angle to the propeller shaft it will materially
expedite the operation of steering.. If it should be thought unnecessary to
employ a rudder in conjunction with the propeller thus mounted, the bearing
for receiving the trunnion of the boss may be carried by a pendent arm or
swinging frame attached like the rudder to the stern post.
Having now set forth the nature of my Invention of an improvement in
the construction of screw propellers, and explained the manner of carrying the
same into effect, I wish it to be understood that under the above in part
recited Letters Patent I claim, so constructing screw propellers that they will
admit of being mounted in such a position on their driving shafts that, the
centre of gravity of the screw propeller will always be in a line drawn through.
the centre of the pintles of the rudder, the screw propeller being at the same
time free to swing on its shaft at the option of the steersman, in the manner
and for the purpose above set forth.
In witness whereof, I, the said William Joseph Curtis, have hereunto
set my hand and seal, the Sixteenth day of December, in the year
of our Lord One thousand eight hundred and sixty-two.
Witness,
J. W. MOFFATT,"
66, Chancery Lane.
W. J. CURTIS. (1..s.)