AN IMPROVED PROPELLER
Year: 1858

page_text: PROVISIONAL SPECIFICATION left by the said Thomas Piatti at the
Office of the Commissioners of Patents, with his Petition, on the
21st July 1858.
I, THOMAS PIATTI, of Paris, France, Gentleman, do hereby declare the
nature of the said Invention for "AN IMPROVED PROPELLER," to be as follows:-
This improved propeller is applicable to the propelling of all descriptions of
ships, and may receive its motion from any suitable prime mover.
The same
consists of a frame composed of two strong circles or wheels fixed parallel to
each other, and at a suitable distance apart as a main or central shaft, and pro-
vided round their periphery with 3 paddles or short oars at equal distance from
each other, which paddles while partaking of the revolving motion of the wheels
are allowed at the same time to turn each of them on a spindle passed through
their centre and fixed to the wheels; one end of each paddle having the form
of two wedges fixed together with their basis, is made heavier than the opposite
end, motion being imparted to the main shaft; this causes each of the paddles
at its turn to immerge in the water, and afterwards to emerge therefrom in
suitable angular position, and thus cause the vessel, provided with this pro-

page_text: peller, to move forward or backward according to the direction in which the
paddles are caused to act, the reversing motion of the paddles taking place by
shifting the position of suitable moveable stops fixed at equal distances apart on
a wheel turning round the main shaft in a concentric manner with the above-
mentioned wheels, other fixed stops serve also for regulating the motion of
the paddles.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Piatti in the Great Seal Patent Office on the 21st
January 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
PIATTI, of Paris, France, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of July, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Thomas Piatti, Her special licence that I, the said Thomas Piatti,
my exécutors, administrators, and assigns, or such others as I, the said
Thomas Piatti, 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 IMPROVED
PROPELLER," upon the condition (amongst others) that I, the said Thomas
Piatti, 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 Thomas Piatti, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
The object of this Invention is to effect a great saving in the power expended
in the propelling of vessels comparatively to the ordinary paddle-wheel or
the archimedian screw hitherto in use, which latter may be superseded with

page_text: great advantage by my improved propeller, which allows of being worked
either partly or entirely immersed in the water.
In the annexed Drawings, Fig. 1 shows my propeller applied to a vessel in
a manner similar to that of the ordinary paddle-wheels of a steamer; Fig. 2
shows a front view of the propeller; and Fig. 3, a cross sectional view of tho
same on a scale about the double of that of Fig. 1. In these three Figures
corresponding parts are indicated by the same letters of reference. The pro-
peller is composed of a frame formed by two strong iron flat rings or wheels
A and A', fixed on an arbor or driving shaft B, and kept parallel to each other
at the required distance apart by means of cross bars or ties C, C¹, C³, provided
with proper screw nuts C³; each of the rings A and A¹ is provided on its
periphery and at equal distances apart with three projecting brackets D, D', D',
forming bearings for the extremities of the spindles E, E, E², of three paddles
F, F, F, so as to allow these latter to turn freely in the said bearings. The
form of these paddles resembles that of two wedges with slightly curved
surfaces, applied against each other with their bases, and each paddle is com-
posed of several layers or thicknesses fffff, applied against each other and
held together towards the ends by screw bolts g, g, g, g, so as to allow of easily
removing, if desired, one or more of these layers f, in order either to diminish
or to increase the acting surface of the paddles, which latter may be made of
wood, metal, or other suitable material, and be made hollow if required. The
arbor or driving shaft B is further provided with a circular plate G resting
against the outside of the ring A', into which plate are solidly fixed, at equal
distances apart, three strong pins h, h', h, which are to act as stops for
regulating partly the position to be assumed by the paddles; these pins
h, h1, h2, glide over the periphery of the ring A', and are thus allowed to shift
position from one projecting bracket D to the other, two curved springs or
catches p¹ and p2, fixed to the inner surface of the ring A', serving for
alternately to take hold of one of the pins; thus, for instance, in Fig. 3 the
pin is shown as kept hold of by the notch n¹ of the spring p¹, whereas, on
turning the plate G from right to left, that is to say, in the direction indicated
by the arrow of this Fig. 3, the pin h¹ will be disengaged from the spring p¹
and the pin h will on the contrary rest in the notch n² of the spring p²; in the
first case the pins will assume the position in which the paddles must be
situated for allowing the vessel to be moved forward, whereas, in the second
case, the position of the pins will allow of the reverse to take place. It must
be remarked here that one of the corresponding ends of each paddle requires
to be made heavier than the opposite end, in order to cause the paddle to fall
down on the respective cross-bar in the required position after having performed

page_text: its action in the water; thus, if the motion is to take place in the direction of
the arrows of the Figs. 1 and 3, the ends P, P1, P2, require to be heavier than
the ends Q, Q, Q%.
The manner in which the propeller is made to act is similar to that of the
ordinary paddle-wheels of steamers, viz., motion being transmitted to the main
arbor or driving shaft B by any suitable prime mover, the propeller will be
obliged to revolve in the same direction as the shaft, viz., in the direction
indicated by the arrows of Figs. 1 and 3, for causing the vessel to advance,
and in the opposite direction for causing this latter to move backward; in the
first case the position of the pins h, h', h², being that indicated in the Fig. 3,
whereas, when the motion is to be reversed the position of these pins must be
shifted in the manner as has been explained here above, and which is easily.
executed by any suitable means, but which I prefer doing by means of a
sort of moveable lever R to one end of which is articulated a handle R',
whereas, the opposite end turns on a pin in the forked end of a ring bracket
R2, with which the driving shaft B is provided, and as the plate G on the
surface opposite to that on which the pins h, h1, h2, are fixed, is also provided
with three pins i, i, 2, projecting a little beyond that surface of the plate, it
will be sufficient to press with the lever R against one of those pins i, ¹, 22,
to cause the plate G to perform a part of a revolution till one of the pins h is
got hold of by the notch of the required spring p, and by which the three pins
h, h', h, will be sufficiently steadied for regulating the action of the paddles."
If now we suppose, for instance, the vessel Fig. 1 is to be moved forward,
then on imparting motion to the driving shaft B, the paddle F, which by the
excess in weight the extremity P¹ has over the opposite extremity Q', will be in
the position indicated in Fig. 1, viz. resting with this extremity P¹ on the cross
bar C, and this paddle will further, by the revolving of the shaft B, enter the
water nearly in the position the paddle F has in Fig. 1, and continue to assume
this position till the weight of the end P of the paddle will cause this end to
fall down, in which position the paddle will follow the action of the water, and
offer but a very small resistance to this latter for immerging in a diagonal
direction from the water, that is to say, nearly in the same manner as the
same has entered the water..
Having thus described the nature of my Invention and the manner in which
the same is or may be carried into effect, I would observe, in conclusion, that
I do not confine or restrict myself to the precise details or arrangements above
described, as many variations may be made therefrom without deviating from
the principles or main features of the said Invention, neither to any metal' or
material in particular from which my propeller or its various parts may be

page_text: made; but what I claim as my Invention is, the general arrangement and
manner of working of my improved propeller for steamers or other vessels, as
herein-before described.
In witness whereof, I, the said Thomas Piatti, have hereunto set my
hand and seal, this Fourteenth day of January, in the year of our Lord
One thousand eight hundred and fifty-nine.
Witness,
J. SOUTH.
THOMAS PIATTI. (L.S.)