AN IMPROVED SCREW PROPELLER AND AN IMPROVED APPLICATION OF THE MOTIVE POWER TO THE PROPELLING OF BOATS AND STEAM SHIPS. APPLICABLE ALSO TO OTHER PURPOSES
Year: 1865

page_text: LETTERS PATENT to John George Hughes, of 158, Strand, in the County
of Middlesex, for the Invention of "AN IMPROVED SCREW PROPELLER AND
AN IMPROVED APPLICATION OF THE MOTIVE POWER TO THE PROPELLING OF BOATS
AND STEAM SHIPS. APPLICABLE ALSO TO OTHER PURPOSES."-A communication
from abroad by Christopher Edward Dampier, residing at Northlands, in
PROVISIONAL SPECIFICATION left by the said John George flughes
at the Office of the Commissioners of Patents, with his Petition, on the
23rd February 1865.
I, JOHN GEORGE HUGHES, of 158, Strand, in the County of Middlesex, do
hereby declare the nature of the said Invention for "AN IMPROVED SCEEW
PROPELLER AND AN IMPROVED APPLICATION OF THE MOTIVE POWER TO THE
PROPELLING OF BOATS AND STEAM SHIPS, APPLICABLE ALSO TO OTHER PURPOSES," to
be as follows:
This Invention consists of a material modification and arrangement of the
wings or screw blades which in rotation assume a spherical or semi-spherical
form, and constitute a series of revolving concentric curved or inclined planes
with a conical tendency for acquiring a greater hold upon the water and
extent of culminating and deflecting surfaces, and obtaining an endwise and
Price 8d.1

page_text: more gradual entrance of the screw blades, for avoiding backwater retention
and acquiring a more general and effective pressure on the resisting medium,
and rendering the backwater pressure effectively available in aid of the
mechanical force applied in order to give increased rotation to the propeller,
and in the adaptation to such propeller in combination therewith of a fixed or
revolving cylindrical exterior, for laterally confining to an endwise direction
or column of water deflected from the propeller so as to create greater
resistance to the motive power applied.
I now proceed to describe this improved propeller, first, in its simple or half-
spherical form, and afterwards in its duplex or entire spherical form. In order
to construct the blades of the half-spherical propeller I take two half-circular
metal plates of the substance and dimensions required, for example, say 4 feet
in diameter or 2 feet on the radii for constructing the two required blades of
a steamer requiring a 4 feet propeller. From these plates I remove a
sufficient portion at their centre to fit them to the shaft or to a cylindrical
tube, which then forms a collar or boss on which the blades are to be fixed
when it is intended to construct the propeller detached from the driving shaft.
I also remove another portion of the plates to permit a free sideways escape-
ment of water in order to relieve the concavities of the blades and interior of
the propeller from backwater retention or any unequal construction of the
blades. The plates, drilled to bolt or rivet to the boss and cross shaft, may
then be bent into their proper shape as presently described, care being taken
in such operation not to disturb the plane lines of radius throughout the disc.
The simple mode in which at present these plates are bent into form is upon a
prepared block or over a conical roller or anvil, with its apex directed to the
centre of the plate, that the plane lines of its radius may be preserved and the
concentric curve spread over the whole periphery in such manner as to produce
at the blade's periphery a curvilinear outline when vertically viewed, the shaft
being set perpendicularly in the ground, by which bending operation the two
sides of the half disc will be brought to form a right angle with each other,
and the periphery of the blade will thus be gradually made to approach the
centre line of the boss throughout the circle. I may now observe that in the
process of bending the plates of the semi-spherical screw into form, a right-
hand blade may be constructed simply by bending the plate down upon the
conical roller in one direction, and a left-hand blade by turning it up over the
roller in the other, but in forming the blades of the entire spherical propeller,
one end of the half-divided disc is to be bent up and the other end down, or
vice versa, in order to form the right and left hand blades. I then make a
cross shaft in length equal to the intended propeller's diameter, with a collar in

page_text: its centre, to be fitted and secured to the boss and shrunk on it. The end of
each blade of the semi-spherical screw is then to be fixed to this cross shaft at
exactly opposite sides of the boss, that end of the blade then standing off the
boss perpendicularly, the ends of the two blades then forming the cutting or
deflecting edges of the propeller in advancing or retiring, and when so
exhibited or fixed to the cross shaft the sides are to be longitudinally placed
and securely fixed along the boss, each exactly opposite the other from end to
end, whereby each blade will partially, circumscribe the boss in a slightly spiral
line, and the same bolts may then serve for securing the two opposite blades
to the boss at one and the same time. The two blades thus fixed compensate
each other and act as one continuous blade, and greatly decreases the vibration
ordinarily occasioned by paddles or detached fans. In this manner the
propeller is constructed and made ready for being attached to the driving or
rotating shaft. I may observe that the longitudinal arrangement of the blades
along the boss and cross shaft is a material feature, inasmuch as the blades
thereby derive the angle of their deflecting surfaces, which may be varied by
the direction given to the cross shaft, and they thereby obtain a direct endwise
and feather-edge entrance into the resisting medium, and in advancing they
receive more active endwise pressure from the backwater, which gives more
speedy rotation to the propeller, and the blades retiring more speedily before
the backwater resistance render the backwater more effectually available for
giving increased rapidity of rotation to the propelling blades in aid of the
mechanical force applied. By these means the backwater resistance is
materially if not wholly avoided, and the mechanical force relieved from the
exhaustion of its power which would otherwise be required and consumed in
overcoming the backwater resistance, which in the case of ordinary screw
propellers arises when the velocity overreaches the stride obtained by the
regular and equal pitch of the ordinary screw blades, but which is remedied by
the peculiar construction and arrangement of the blades of this propeller for
increasing the speed of rotation without an equivalent expenditure of steam for
obtaining that object. To this semi-spherical propeller also apply at the
deflecting edges a shifting angular plate or additional blade, which may be
attached or detached at pleasure by means of the bolts, in order simply to vary,
increase, or diminish the angle of deflection from time to time so as to apply
greater force of propulsion without increasing the speed of the engines.
I now proceed to describe the improved propeller when the blades are
extended so as to compass an entire sphere in rotation. The construction of
this extended propeller is based entirely upon the same principles which are
developed in the semi-spherical propeller described, premising that the exten-

page_text: sion of the blades in rotation makes it assume an entire spherical appearance
and adds greatly, to the force it may communicate; that the shaft. or boss
must be proportionally extended in length, and that when it is purposed to
use the same half-circular plates or blades in their bent form, four half-circular
plates. or blades will be required to form the two propelling blades of the
spherical screw instead of two viz., one right-hand and one left-hand blade
which must be conjoined to form each blade and rivetted together at the sides,
the two plates thus joined are then to be fixed to the cross, shaft and to the
boss longitudinally, and secured along the boss on opposite sides of the shaft
as before stated, which will complete the spherical propeller for fixing on the
rotating shaft. If preferable, each blade of this duplex propeller may be made
of an entire circular plate of metal and bent into shape for better fitting them
to and round the boss.
The second part of the Invention comprises and refers to the application of
an exterior cylinder round about the propeller described, either fixed or
rotating, for laterally confining to an endwise direction the column of water
deflected or ejected by the interior propeller, in order to increase the direct
endwise force of resistance, and to oppose cross action when desired to the
column of water within the cylinder by means of spiral or other blades attached
to such cylinder for giving it spiral rotation.
SPECIFICATION filed in pursuance of the conditions of the Letters Patent,
and of an Order of the Lord Chancellor, by the said John George Hughes
in the Great Seal Patent Office on the 2nd September 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN GEORGE
HUGHES, of 158; Strand, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of February, in the year. of our
Lord One thousand eight hundred and sixty-five, in the twenty-eighth year of
Her reign, did, for Herself, Her heirs and successors, give and. grant unto
me, the said John George Hughes, Her special licence that I, the said John
George Hughes, my executors, administrators, and assigns, or such others as
I, the said John George Hughes, 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

page_text: IMPROVED SCREW PROPELLER AND AN IMPROVED APPLICATION OF THE MOTIVE POWER
FOR PROPELLING BOATS AND STEAM SHIPS. APPLICABLE ALSO TO OTHER PURPOSES," a
communication to me from abroad by Christopher Edward Dampier, a person
residing at Northlands, in the Province of Canterbury, New Zealand; upon the
condition (amongst others) that I, the said John George Hughes, 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 Jolin George Hughes, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:
This Invention consists of a material modification and arrangement of the
wings or screw blades, which in rotation assume a spherical or semi-spherical
forni and constitute a series of revolving concentric curved or inclined planes
with a conical tendency, for acquiring a greater hold upon the water and
extent of culminating and deflecting surfaces, and obtaining an endwise and
more gradual entrance of the screw blades, for avoiding backwater retention
and acquiring a more general and effective pressure on the resisting medium,
and rendering the backwater pressure effectively available in aid of the
mechanical force applied in order to give increased rotation to the propeller,
and in the adaptation to such propeller in combination therewith of a fixed or
revolving cylindrical exterior, for laterally confining to an endwise direction
the column of water deflected from the propeller so as to create greater
resistance to the motive power applied.
.
I now proceed to describe this improved propeller, first, in its simple or
half-spherical form, and afterwards in its duplex or entire spherical form,
referring to the Drawings annexed for better explication thereof.
Figure is a half-circular disc or metal plate of the substance required, of
which the blades are to be formed, as shown in Figure 2; Figure 2 gives a
side view of a blade curved or bent into shape for fixing on the driving shaft;
Figure 3 is an end view of one of these blades, shewing the outline of the
blade's periphery, to which Figure a scale is attached by which the curvilinear
outline of the blade may be set; the scale being made to obtain an equal and
gradual contraction of the blade's exterior outline towards the centre of the
shaft on which it rotates, by which means the concentric operation of the
blades is obtained. Figure 4 is a vertical view of one of these half-spherical

page_text: propellers with two blades, the shaft lying in a horizontal position as applied
Funder the counter of a steamer, and the propeller as one of two twin screws.
As shown in this Figure the propeller is applied as a deflecting screw deriving
rotation from the backwater pressure within the semi-conical blades, as the
ship advances in aid of the mechanical force applied by the ship's engine.
This propeller, which I call semi-spherical, may be reversed on the shaft and
then used as a culminating screw, with greater advantage than an ordinary
screw blade, by the greater hold which it attains on the resisting medium.
Figure 5 is a back end view of the propeller when advancing as a culminating
screw, and a front view of the same propeller when advancing as a deflective
screw; in the latter case the main lines of deflection are off the radius
lines a, c. Figure 6 is a front view of the half-spherical propeller advancing
as a culminating screw. The blades of this propeller are to be constructed of
a true concentric and partially conical form with convex and concave surfaces.
In order to construct the blades of the half-spherical propeller I take two
half-circular metal plates, as shewn in Figure 1, of the substance and dimen-
sions required; for example, say 4 feet in diameter, or 2 feet on the radii, for
constructing the two required blades of a steamer requiring a 4 feet propeller.
From these plates I remove a sufficient portion at their centre, as shown in
Figure 1, to fit them to the shaft or to a cylindrical tube, which then forms a
collar or boss on which the blades are to be fixed when it is intended to
construct the propeller detached from the driving shaft. I also remove another
portion of the plates, as shown at e, to permit a free sideways escapement of
water, in order to relieve the concavities of the blades and interior of the
propeller from backwater retention or any unequal construction of the blades.
The plates, drilled as shewn in the Drawing Figure 4, to bolt or rivet to the boss
and cross shaft, may then be bent into their proper shape as presently described,
care being taken in such operation not to disturb the plane lines of radius
throughout the disc. The simple mode in which at present these plates are
bent into form is upon a prepared block or over a conical roller or anvil,
with its apex directed to the centre a of the plate, that the plane lines of its
radius may be preserved, and the concentric curve shewn in Figure 3 spread
over the whole periphery, in such manner as to produce at the blade's periphery
the curvilinear outline shown in Figure 3 when vertically viewed, the shaft a
being set perpendicularly in the ground, as shown in that Figure, by which
binding operation the side a, b, of the half disc will be brought to form a right
angle with the side a, c, and the periphery of the blade will thus be gradually
made to approach the centre line of the boss throughout the circle, as shewn
in that Figure 3. The true construction of the curved blade may then be

page_text: tested by application thereto of the scale of parts shown in that Figure. The
scale referred to is thus formed:-I divide the radius a, c. into a given number
of, say 16 equal parts, and I divide the whole circle within which the blade is
to revolve (shown by the dotted lines) into the same number of equal parts,
say 16. From the centre a to each of the divisions on the periphery of the
circle I draw lines as shown, minus the successively increasing number of
parts on the radius, so as to form the given curve, which will then indicate the
gradual nearer approach of the blade's periphery to the central line of the
boss, the distances from the centre to the blade's periphery at the several
desired points being taken on the horizontal line.
I may now observe that in the process of bending the plates of the semi-
spherical screw into form, a right-hand blade may be constructed simply by
bending the plate down upon the conical roller in one direction, and left-
hand blade by turning it up over the roller in the other but in forming the
blades of the entire spherical propeller, one end of the half-divided disc shewn
in Figure 10 is to be bent up and the other end down, or vice versa, in order
to form the right and left hand blades. I then make a cross shaft in length
equal to the intended propeller's diameter, with a collar in its centre, to be
fitted and secured to the boss and shrunk on it. The end or side a, c, of eacli
blade of the semi-spherical screw is then to be fixed to this cross shaft, at
exactly opposite sides of the boss, as shown in Figure 4; that end of the blade
then standing off the boss perpendicularly, the sides a, c, of the two blades
then forming the cutting or deflecting edges of the propeller in advancing or
retiring, and when so exhibited or fixed to the cross shaft the sides a, b, are
to be longitudinally placed and securely fixed along the boss, each exactly
opposite the other from end to end, whereby each blade will partially circum-
scribe the boss in a slightly spiral line, and the same bolts may then serve for
securing the two opposite blades to the boss at one and the same time. The
two blades thus fixed compensate each other and act as one continuous blade.
and greatly decreases the vibration ordinarily occasioned by paddles or de-
tached fans. In this manner the propeller is constructed and made ready for
being attached to the driving or rotating shaft.
1 may observe that the longitudinal arrangement of the blades along the
boss and cross shaft is a material feature, inasmuch as the blades thereby
derive the angle of their deflecting surfaces, which may be varied by the
direction given to the cross shaft, and they thereby obtain a direct endwise
and feather-edge entrance into the resisting medium, and in advancing they
receive more active endwise pressure from the backwater, which gives more
speedy rotation to the propeller, and the blades retiring more speedily before

page_text: the backwater resistance render the backwater more effectually available for
giving increased rapidity of rotation to the propelling blades in aid of the
mechanical force applied. By these means the backwater resistance is mate-
rially if not wholly avoided, and the mechanical force relieved from the
exhaustion of its power, which would otherwise be required and consumed in
overcoming the backwater resistance, which in the case of ordinary screw
propellers arises when the velocity overreaches the stride obtained by the
regular and equal pitch of the ordinary screw blades, but which is remedied
by the peculiar construction and arrangement of the blades of this propeller
for increasing the speed of rotation without an equivalent expenditure of
steam for obtaining that object. To this semi-spherical propeller I also apply
at the deflecting edges a, c, a shifting angular plate or additional blade, which
may be attached or detached at pleasure by means of the bolts shewn, in order
simply to vary, increase, or diminish the angle of deflection from time to time
so as to apply greater force of propulsion without increasing the speed of the
engines.
I now proceed to describe the improved propeller when the blades are
extended so as to compass an entire sphere in rotation.
Figure 10 is an entire circular plate intended to form one of the two blades
of this propeller; Figure 11 a side view of one of the blades when bent into
its double concentric form; Figures 12, 13, & 14, are three side views of
different positions which it takes in one rotation of the propeller; Figure 15
is a three-quarter perspective view of the propeller; and Figure 16 a side
view of the propeller and the exterior cylinder when applied in combination
as after mentioned.
The construction of this extended propeller is based entirely upon the same
principles which are developed in the semi-spherical propeller described,
premising that the extension of the blades in rotation makes it assume an
entire spherical appearance and adds greatly to the force it may communicate;
that the shaft or boss must be proportionally extended in length, and that
when it is purposed to use the same half-circular plates or blades in their
bent form. four half-circular plates or blades will be required to form the two
propelling blades of the spherical screw, instead of two, viz., one right-hand
and one left-hand blade. which must be conjoined, as shewn in Figure 11, to
form each blade, and rivetted together at the sides a, c. The two plates thus
joined are then to be fixed to the cross shaft and to the boss longitudinally,
and secured along the boss on opposite sides of the shaft as before stated,
which will complete the spherical propeller for fixing on the rotating shaft.
If preferable, each blade of this duplex propeller may be. made of an entire

page_text: circular plate of metal, as shewn in Figure 10, and bent into shape, as in
Figure 11, the parts being removed as shewn in those Figures for better"
fitting them to and round the boss.
The second part of the Invention comprises and refers to the application of
an exterior cylinder, as shewn in Figure 16, round about the propeller de-
scribed, either fixed or rotating, for laterally confining to an endwise direction
the column of water deflected or ejected by the interior propeller, in order to
increase the direct endwise force of resistance, and to oppose cross action when
desired to the column of water within the cylinder by means of spiral or other
blades attached to such cylinder for giving it spiral rotation.
I claim therefore as the Invention the improved propeller described, and
the improved modification and arrangement of the blades, and application of
the cross shaft, and shifting angular blades for regulating the operation of the
propeller, and as an improved means of rendering the backwater available
for acquiring increased rapidity of rotation to the propeller, in aid of the
mechanical force applied, and as a better means of applying the mechanical
force for obtaining increased speed from a given propelling power.
In witness whereof, I, the said John George Hughes, have hereunto set
my hand and seal, this Twentieth day of July, in the year of our
Lord One thousand eight hundred and sixty-five.
JNO. GEO. HUGHES. (L.S.)