AN IMPROVED REVOLVING PROPELLER FOR STEAM-VESSELS."
Year: 1882

page_text: LETTERS PATENT to Charles Corneby, of Poplar, in the County of Middlesex,
Nail Makor, for an Invention of "AN IMPROVED REVOLVING PROPELLER FOR
STEAM-VESSELS."
PROVISIONAL SPECIFICATION left by the said Charles Corneby at the Office
of the Commissioners of Patents on the 20th January 1882.
CHARLES CORNEBY of Poplar in the County of Middlesex, Nail Maker.
IMPROVED REVOLVING PROPELLER FOR STEAM VESSELS."
<< AN
The object of this Invention is to increase the speed of steam vessels without
augmenting the engine power of such vessels.
On the usual boss of a vessel's propeller, I fit and fix two or more propeller
blades, by preference three; which blades are formed as follows:-
I divide the length of the blade into twelve equal parts; four of such parts are
taken for the measure of the width of the blade at the root thereof; three-and-a-
half such parts are taken for the width of the blade, from the centre line to the
trailing edge thereof, at about the distance of two such parts from the extreme end
of the blade; the leading edge of the blade is a semicircle or thereabouts. The
working face of the blade, when the vessel is going a-head, I make concave at a
radius equal to the diameter of a circle bounding the whole propeller; the circum-
ferential curve, or the curve in the width of the blade, I make at a radius varying
from the said diameter to about half such diameter, to suit the pitch of the blade;
these two operations make the face of the blade concave or dished, and the back
thereof convex; thus enabling it, when working, to take greater hold of the water,
and also to lessen the vibration caused by the ordinary propeller.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Corneby in the Great Seal Patent Office on the 26th July
1882.
CHARLES CORNEBY of Poplar in the County of Middlesex, Nail Maker.
IMPROVED REVOLVING PROPELLER FOR STEAM VESSELS."
"AN
The object of this Invention is to increase the speed of steam vessels without
augmenting the engine power of such vessels, and to reduce the vibration or
tremulous motion thereof, so fruitful a cause of sea-sickness.
In order that iny said Invention may be more thoroughly understood and be
more readily performed, I will explain the same with the aid of the accompanying
Drawing, which forms part of this Specification; reference being made thereto by
the numerals and letters marked thereon; the same index letter refers to similar
parts in cach Figure of the said Drawing.
Fig. 1 is a front view of my improved propeller, as mounted on the operating
shaft of the vessel.
Fig. 2 is a horizontal side view of the said propeller.
Fig. 3 is a vertical side view thereof.
Fig. is a vertical section through the centre of each blade of the propeller.
Fig. 5 is horizontal section through the widest part of the blade.
Fig. 6 is a full face view of one of the said blades, to enable me the better to
explain my method of shaping them.
Figs. 4 and 5 are drawn to a larger scale, so that the curve of the blades, each
way, may be more distinctly seen,
My-improved-propeller-is constructed-on the principle of tho revolving. cutter,
as used in cutting or boring holes through wood and other solid materials. The
principle of the usual screw propeller (a helical thread around a cylinder) being
entirely superceded thereby.
In constructing my said propeller, I proceed as follows:-
Having settled the length of the propeller blades a, which varies according to
the form and tonnage of the vessel to be propelled; I divide the said length into 12:
equal parts; four of such parts, two on each side of the centre line of the blade,
constitute the width of each blade at the root a¹, Fig. 1, thereof.
At two such parts from the extreme end of the blade, on the centro line, at b,
I set off 3 of the said parts, at right-angles thereto, to the trailing edge of the
blade, or from 6 to c, which gives the widest part of the trailing portion of the
blade. With a radius equal to the diameter of the propeller, X Y, say from the
point, the curved trailing edge of the blade is struck from c to a². Then from
the point d, 14 parts froin b, on the line bc, with a radius of two parts, the curve
from c to e is struck, which completes the trailing edge of the blade.
For the leading edge, I draw the line fe, the latter point e being 14 parts from
the centre line, e es, the same as the point d; half the length of this line is the
radius for the leading edge of the blade, which is semicircular; the point g, from
which this semicircle is struck, is determined by describing two arcs, with a radius
of half the length of the line e f; from the points fand e³, which intersect each
other at the said point g. With the same radius, from the point g, the leading
edge of the blade is struck from e² to f. The points e and e³ are connected by a
straight line or by a very slight curve; which completes the outline of the blade.
The said leading edge, when revolving, forms a true cutting edge. See Fig. 6.
The faces of the blades are curved or hollowed both longitudinally and trans-
versely, see Figs. 4 and 5. The longitudinal curve, on the face of the blade, from
h to i Fig. 4, is struck with a radius equal to the propeller's diameter, X Y Fig. 6,
the same as the curve, a³c Fig. 6. of the trailing edge of the blade.

page_text: The transverse curve, on the face of the blade, from j to k Fig. 5, is struck with
a radius of three-fourths of the said diameter X Y, or thereabouts.
My improved blades are set at any angle, with the centre line lm of the boss n
and of the driving shaft, varying from 45° to 70°; the present illustration being
set at 60°.
Neither the blades nor my improved propeller in its entirety, have any twist
nor the principle of the screw in them.
From the diameter of the propeller all the other dimensions and the radii of
the curves thereof are determined; thus keeping all the parts of the propeller, of
whatever size, in the same ratio.
This improved propeller is so arranged that the blades thereof cut their way
into the water, instead of screwing themselves therein, and have consequently a less
sudden resistance or shock from the water, which increases the power and rapidity
of motion of the propeller, and considerably reduces the vibration usually imparted
to vessels by the ordinary screw propeller.
Having thus fully described and ascertained the nature of my said Invention
and the method of performing the same, I claim as my Invention, and desire to
secure by the hereinbefore mentioned in part recited Letters Patent, the con
struction of a propeller, with two or more blades, for propelling vessels, on the
principle of a revolving cutter, substantially as herein described and shown in the
Drawing.
In witness whereof I, the said Charles Corneby, have hereunto set my hand
and seal this Twentieth day of July in the year of our Lord One thousand
eight hundred and eighty two.
CHARLES CORNEBY. (L.S.)