CERTAIN IMPROVEMENTS IN THE CONSTRUCTION AND ADAPTATION OF A REVOLVING SPIRAL PADDLE FOR PROPELLING BOATS AND OTHER VESSELS ON WATER
Year: 1832

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENNET
WOODCROFT, of Manchester, in the County Palatine of Lancaster, Printer,
send greeting.
WHEREAS His most Excellent Majesty King William the Fourth did,
by His Letters Patent under the Seal of Great Britain, bearing date at West-
minster, the Twenty-second day of March, in the second year of His reign,
give and grant unto me, the said Bennet Woodcroft, my executors, adminis-
trators, and assigns, His especial licence that I, the said Bennet Woodcroft,
my executors, administrators, and assigns, should and lawfully might, during
the term of fourteen years therein mentioned, make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, my Invention
of "CERTAIN IMPROVEMENTS IN THE CONSTRUCTION AND ADAPTATION OF A REVOLVING
SPIRAL PADDLE FOR PROPELLING BOATS AND OTHER VESSELS ON WATER;" in
which said Letters Patent is contained a proviso, that if I, the said Bennet
Woodcroft, should not particularly describe and ascertain the nature of my
said Invention, and in what manner the same is to be performed, by an instru-
ment in writing under my hand and seal, and cause the same to be enrolled
in His Majesty's High Court of Chancery within six calendar months then
next and immediately after the date of the said Letters Patent now in
recital, that then the said Letters Patent, and all liberties and advantages
thereby granted, should utterly cease, determine, and become void, as in and
by the same, reference being thereunto had, may more fully and at large
appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Bennet Woodcroft, do hereby declare that my said Invention consists in a
spiral paddle made of wood, metal, or any other suitable material of the
following construction, by the revolution of which boats or other vessels may
be propelled on water, that is to say:―
A spiral worm, blade, or screw coiled round a shaft or cylinder of any con-
venient length and diameter, in such form that the angle of inclination which
the worm makes with the axis of the cylinder continually decreases, and the
pitch or distance between..the coils or revolutions of the spiral continually
increases throughout the whole length of the shaft or cylinder upon which the
spiral is formed, the effect of which construction is as follows:-The spiral
paddle being made to rotate in the water, when the commencement of the
spiral blade, or that part of it which-forms the- greatest angle with the shaft,
acts upon the water, it gives to it an impetus or motion towards the back end
of the paddle, thus creating a current in the direction of the spiral. If this
current were to reach the succeeding or following parts of the spiral paddle
before those parts take their action upon the water, such following parts would
move in or keep pace only with the current, and would therefore meet with
little or no resistance from the receding water, and a part or the whole of their
action would be lost, or without effect; but by progressively elongating the
pitch of the spiral, each successive part of the spiral begins to act before it is
overtaken by the current given to the water by the action of the preceding
part of the spiral, and consequently every part meets resistance from the water,
and thereby gains a portion of propelling power.
And in further compliance with the said proviso, I, the said Bennet Wood-
croft, do hereby declare that the manner in which my said Invention is to be
performed and put in operation is particularly ascertained and described by
the Figures contained in the annexed Sheet of Drawings, and the following
description, that is to say:-
Fig. 1, in the Sheet of Drawings hereunto annexed, is a side view of a
steam boat fit for canal and coasting navigation. To this steam boat are
applied two spiral paddles, one on each side, with their spirals cut in opposite
directions, one as a left and the other as a right hand screw; these paddles
are placed with their axles horizontally in the water, and parrallel to the direct
line of motion of the vessel, that end of each spiral which presents the shortest
pitch or quickest coil being next to the bow of the vessel. One of these
paddles only, marked A, is seen in this Figure. The said paddles are so
placed that the lower edges of the spiral are a few inches above the level of the
bottom of the keel of the vessel, and their diameters are such that the upper

page_text: edges of the said spiral shall be a few inches below the surface of the water when
the vessel is carrying its usual burden. Hence the draught of the vessel, or
the depth at which she floats when loaded, regulates the diameter of the spiral
paddle when intended to be employed under total immersion. The length of
the spiral paddles may be varied according to the power required. The shaft
of each paddle is supported upon a neck or pivot at each end, and works in
carriages or brackets, marked B, B, which are firmly bolted to the side of the
boat. A crank, marked C, is fixed to the back end of the shaft of each
paddle, from which a connecting rod, marked D, passes upwards through
the sides of the vessel, and communicates with the steam engine or other
prime mover in the vessel. When the vessel is to sail, the spiral paddles are
made to rotate in opposite directions by any of the ordinary means of con-
verting and transmitting the motion generated by the prime mover. The
spiral paddles being thus made to rotate in contact with the water, the
spiral paddles and the water act together on the principle of the nut and
screw, the water being the nut, and the spiral paddle the screw, and the vessel
thus receives a progressive motion through the water. The ratio of motion
thus obtained will depend upon the speed at which the spiral paddles are
made to rotate upon their axles, and the power of propelling upon the
diameter and length of the spiral paddle, together with the ratio or degree of
the increasing inclination of the spiral blades towards their axles of the
paddles.
Fig. 2 is an end view of the steam boat, as seen from its back or aft end.
A, A, represent the back ends of the spiral paddles, which are here represented
as recessed into the sides of the hull of the vessel. This mode of applying
the paddles affords a protection to them from injury, and causes the vessel to
which they are applied to occupy less room in width. But if this mode should
cause the vessel to draw more water than the navigation will admit, the paddles
may be partly let into the side, or not let in at all, as represented in Figure 4, in
which cases the paddles should be protected by a frame or over-hanging deck,
marked E, F, in the same Figure, and also represented by the dotted lines E, F,
in the plan of the vessel, Figure 3. The spiral paddles may also be placed
under the stern of the vessel instead of at the sides, as seen in Figure 5 and
Figure 6, where a part of the hull is removed, and the paddles (marked G, H, I, J,
in Figure 6,) are introduced into the space, and are firmly fixed to the boat
and connected with the steam engine by suitable intervening machinery. A
protection is also by these means afforded to the paddles without augmenting
the width of the vessel.
Fig. 5 represents two paddles H and J, being part of a combination of four

page_text: spiral paddles. If the draught of the vessel is great this combination may be
used with good effect, because when the paddles are turned in the direction of
the arrows, the surfaces of the spiral worms will act against a column of water
in a manner approximating to the action of the piston of a forcing pump.
Fig. 7 represents two sets of spiral paddles, each consisting of four paddles,
like the one last described, and which may be employed where great power is
required. Fig. 8 is another combination of two paddles K and L, adapted
for narrower vessels. Figs. 9 and 10 are combinations suitable for boats of
wider dimensions, the former having three spiral paddles M, N, O, and the
latter having four P, Q, R, S; both of which combinations, as well as that
shewn in Figure 8, may be adapted to vessels of any draught. Fig. 11
represents another modification, in which the paddle T works with not more
than half its diameter in water when the vessel is loaded to its greatest
draught. This paddle might be made much greater in diameter, and shorter
in length, than any of the paddles which are made to work totally immersed.
The manner in which I describe a spiral blade varying in its pitch or
inclination to the axis of the paddle, in such ratio or degree as I consider best
adapted for the said purpose of propelling vessels, is as follows, videlicet:-Let
I, J, be a right line, equal to the direct length of the spiral part of the paddle
required; and on I, J, describe the square I, J, K, L; draw a diagonal from
the angle I to the opposite angle L, which line will form an angle with the line
I, J, of forty-five degrees; then divide the side J, K, of the square into four
equal parts, as at 1, 2, 3, 4, and through the point I of these divisions draw
the line c, d, parallel to the line I, J; from the angle I of the square draw the
line I, e, at an angle of fifty-five degrees with the line I, J, and where the line
I, e, intersects the horizontal line c, d, at the point h, it gives a point through
which the segment of a circle f, g, must be drawn from the angle I to the
angle L of the square I, J, K, L. If, then, the paper or other medium upon
which this segment of a circle f, g, is drawn be transferred to or rolled on a
cylinder, the radius of which is equal to the radius of the spiral worm, the
segment of a circle f, g, will describe upon the surface of such cylinder the
outer circumference of the spiral worm required.
And I declare that although I consider a spiral blade so produced as afore-
said the best adapted for a paddle wheel for the said purpose of propelling
boats or other vessels on water, I do not confine myself to the aforesaid or to
any particular ratio or degree of increasing pitch or inclination in the spiral
blade of my said paddle
And I claim, as of my Invention, the construction and adaptation for the
purpose aforesaid of a spiral paddle, in which the pitch or inclination of the

page_text: spiral blade to the axis of the paddle continually increases, whatever be the
ratio or degree of such increase.
And I further declare that although I have herein-before described several
combinations of my said improved paddles in order to illustrate the use and
employment thereof for the said purpose of propelling boats or other vessels
on water, yet I do not confine myself to any particular arrangement or com-
bination of my said paddles in the employment thereof for the aforesaid
purpose, nor do I confine myself to any particular number of paddles to be
so employed, inasmuch as my said improved paddles may be employed for the
purpose aforesaid in various arrangements and combinations, and either singly
or in combinations of two or more.
In witness whereof, I, the said Bennet Woodcroft, have hereunto set
my hand and seal, this Twentieth day of September, in the year of our
Lord One thousand eight hundred and thirty-two
BENNEI (L.S.)
CROFT.
AND BE IT REMEMBERED, that on the Twentieth day of September, in
the third year of the reign of His present Majesty King William the Fourth,
the said Bennet Woodcroft came before our Lord the King in His Chancery,
and acknowledged the instrument aforesaid, and all and every thing therein
contained and specified, in form above written. And also the instrument afore-
said was stamped according to the tenor of the Statute made in the fifty-fifth
year of the reign of His late Majesty King George the Third.