IMPROVEMENTS IN PROPELLING
Year: 1852

page_text: LETTERS PATENT to James Spotswood Wilson, of Tavistock
Place, in the County of Middlesex, Civil Engineer, for the
Invention of "IMPROVEMENTS IN PROPELLING."
Scaled the 8th June 1853, and dated the 8th December 1852.
PROVISIONAL SPECIFICATION left by the said James Spotswood
Wilson at the Office of the Commissioners of Patents, with his
Petition, on the 8th December 1852.
I, JAMES SPOTSWOOD WILSON, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN PROPELLING " to be as follows:-
My Invention is based on two philosophical principles.
First, that water increases in force in an equal ratio with the
square of its depth, which proportions correspond with that of an
angle of 45 degrees.
Secondly, that gravity, acting on an inclined plane, produces
locomotion in an equal degree with the increase of the angle of in-
clination, the means of which is also found at an inclination of 45
degrees from the horizon.
These angles correspond with a line drawn intermediate to the
radius and tangent lines, which I therefore name the inter-tangent

page_text: force, which, as applied to steain or other ships, is an entirely novel
principle in machinery.
I therefore propose to place propellers at each side of a vessel
(say a screw on a shaft). The main shaft passing through a vessel
where paddle-wheels are used is fixed in a horizontal position, and
so rotates.
I intend, by certain gearing of wheels (which it is considered un-
necessary to describe here), to cause this rotation to act upon the
upper end of a shaft, which is placed outside a vessel, having, at its
lower extremity (which is always immersed in the ocean or other
waters), a screw of the usual description of propeller. The portion
of this shaft is inclined towards the stern, say at an angle of 45
degrees from the horizon. And as the main shaft rotates in the
usual manner, it causes this shaft (which I term a wing shaft or
propeller) to rotate, and the propeller to work.
If two of my propellers be used, they should be placed at or
somewhat forward of midships, so as to take the bearing at or neur
the centre of gravity; if 4 or any other number be used, I would
dispose them so as to take the bearing of the ship equally. The
principle upon which these propellers will act is somewhat similar
to that in which a man or number of men with poles pressing an-
gularly against the bottom of a river force a boat onward. The
man bearing angularly against the boat produces that motion. In
this instance the angular position of the poles represents that of the
propellers, and the effect produced by the men in the angular
attitude represents the effect that would be produced by the gravi-
tating influence of the ship.

page_text: SPECIFICATION in pursuance of the conditions of the Letters
Patent, filed by the said James Spotswood Wilson in the Great
Seal Patent Office on the 8th June 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
JAMES SPOTSWOOD WILSON, of Tavistock Place, in the County of
Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of December, in the
year of our Lord One thousand eight hundred and fifty-two,
in the sixteenth year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said James Spotswood
Wilson, Her special licence that I, the said James Spotswood
Wilson, my executors, administrators, and assigns, or such others
as I, the said James Spotswood Wilson, my executors, adminis-
trators, 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 "IMPROVE-
MENTS IN PROPELLING," upon the condition (amongst others) that I,
the said James Spotswood Wilson, 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 James Spotswood Wilson, 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, reference being
also had to the sheet of Drawings hereunto annexed (that is to say):
The nature of my improvements are the application of a propel-
ling force to a steam ship or other vessel. The proper place for the
application of such force, in order to promote horizontal motion, I

page_text: conceive to be at the centre of gravity, and this (in other cases) is
generally found true in practice, because at that point the gravi-
tating disposition of the body (as, for instance, in the paddle wheel
of the steam ship and the driving wheel of the locomotive steam
engine) is the proper position in which to apply the force in order
to produce the largest amount of horizontal motion in proportion to
the power employed. I learn from many examples, both in nature
and art, that such position is at an angle of inclination forty-five
degrees from the horizon. But my principal reason for adopting
that angle with regard to marine propellers is in consideration of the
fact that water increases in force in an equal ratio with the depth
from which arises its mean resistance at that inclination, and that
the mean velocity of a falling body is obtained in that inclination
also. By causing the power to act in the line of the former at that
angle upwards, gravity will be brought into action at a correspond-
ing angle downward, but at right angles to the former, the resultant
of which will be horizontal motion. In natural examples we find
that the fastest swimmers among fishes have their tails divided into
long tapering lobes, instead of one broad sheet, and the swiftest
among birds have long tapering wings. In imitation of these
models afforded by nature I form my propeller, and therefore term
it the wing propeller, not only on account of its situation and form,
but likewise to distinguish it from the screw propeller, as it does
not retain any portion of the spiral character.
The vibration experienced in screw propelled ships arises from
the unequal density of the water in which the propeller acts; the
force opposed increases in proportion to the depth, the violence of
the vibration is in proportion to the velocity.
By the application of the wing propeller in the angular position,
as represented in the Drawings Figure 1, the vibration would be
completely removed, in consequence, first, of their acting in the line
of mean resistance, by which means the difference arising from
density would be one half equalized; and, second, their blades being
made tapering towards their outward extremities, the forces and
velocities would be more equally proportioned to the different

page_text: sections of the diameter. Figure 2, is a Drawing of the propeller
which represents a pair of revolving wings. At Figures 3, and 4,
it will be seen that the descending wings D, D, act, like those of a
bird, nearly horizontal, but ascending in the line of mean resistance;
while the descending blades E, E, rise in a nearly vertical position,
and press backward at the same time in a manner similar to the
action of an oar in rowing.
The manner in which I propose to make the wing propeller
suitable as an auxiliary power is according to the following
description: Figure 2, represents on a large scale the propeller and
shaft; the latter is traversed spirally by a broad screw thread, on
which the propeller fits, and while it is kept at work the action
will keep it firmly down to the collar A; but when the engine
is stopped, and the ship continues in motion, the resistance of the
water will cause the propeller to turn on the shaft, and in so doing
it will travel up the screw, so that all that is necessary to be done,
in order to draw the propeller out of the water, is to stop the
engine or reverse the motion. In ocean steamers, the necessity for
being able to back water is not great, and is likely to occur only
when coming into or leaving port, and would therefore prefer
to avoid providing for that evolution, rather than incumber my
apparatus with a complicated mechanical arrangment. Yet, that
my auxiliary shaft and propeller may be as perfect as possible,
I contrive to key the propeller to its place in such simple a manner
that it may be secured or liberated in a moment. To effect this, I
propose making the screw thread on the shaft considerably broader
than the space beween its spiral revolution, than by having a key
way running the full length of the screw on the shaft, and sunk
about half an inch deeper than the spiral thread, and a correspond-
ing way inside the propeller also; the lower end of the key should
be formed so as to make good the deficiency of the screw thread,
when the propeller is at liberty to ascend, but having space
enough at its lower end to allow of its being driven down, so as to
permit the portions of the thread on the key to pass across the
space as shown at c, c, c, Figure 2, by which means the propeller

page_text: would be prevented from turning on the shaft. The upper end of
the key should be furnished with the nut B, fitted in such a
manner that when being run on it would drive the key down, and
on being drawn off it would draw the key with it and liberate the
propeller. In applying the power, I propose using only one steam
engine for one pair of propellers by placing the cylinder thereof
horizontally across the ship, level with, and in a line with the
centres of the two cranks B, B, Figures 3, and 4, and furnishing it
with one piston and two piston rods, or rather one piston rod
passing through the piston and out of each end of the cylinder, so
as to act like a double engine, by having each end connected with a
crank rod. Figures 3, and 4, represent the mode of application,
by comparing which with the modes in use may be observed
the amount of machinery that would be dispensed with and the
smallness of the space that need be occupied by the engine. To
increase the velocity of the ship under this arrangement the
propeller wings should be lengthened, the stroke of the engine
shortened, and the diameter of the cylinder increased to compensate
for loss of leverage in the cranks. But as regards engines such as
are constructed in the paddle wheel steam ships they may be
applied by using bevil gear, to connect the propeller and engine
shafts, and to multiply the velocity to the required amount.
Having now described the whole of my Invention of "Improve-
ments in Propelling," in compliance with the proviso before
mentioned, and the manner in which the same is to be carried into
practical effect, I desire it to be understood that wherever I have
described a combination of parts, that I lay no claim to the parts
taken seperately, or to the material or materials of which such part
is or may be composed, except in such case as I may have reserved
and claimed the same; and I would observe, that where sizes,
proportions, or positions are given, I have endeavoured to give
nearly as possible those most correct; but I do not confine myself to
them as set down or mentioned, as it is evident that, under various
circumstances, such proportions, sizes or positions, may be varied to
suit or apply to such circumstances as the different description of
shipping to which my Invention is applicable may require.

page_text: But what I do claim as of my Invention, and as protected by the
Letters Patent aforesaid, is,-
Firstly, I claim the peculiar form of the propeller blades herein-
before described and illustrated in the annexed Drawing.
Secondly, I claim the exclusive right of fixing a shaft or rod at
or on the sides of a ship or other marine vessel in an angular
position, as herein-before described.
Thirdly, I claim the connecting of these shafts or rods by cranks
to the pistons of a steam engine, the cylinder of which engine shall
be laid horizontally athwart the ship, and have a piston rod
working through each end.
Fourthly, I claim the mode of lifting the propeller by means of a
spiral thread or screw encircling the shaft as described.
In witness whereof, I, the said James Spotswood Wilson,
have heretofore affixed my hand and seal, this Eighth
day of June, One thousand eight hundred and fifty-
three.
Witness,
JOHN GEDGE,
JOHN SPOTSWOOD WILSON. (L.s.)
Patent Agent,
4 Wellington Street,
Strand.