IMPROVEMENTS IN SCREW PROPELLERS, AND IN SHIPS OR VESSELS.
Year: 1854

page_text: LETTERS PATENT to Edmund Hunt, of Glasgow, in the County of Lanark,
North Britain, Gentleman, for the Invention of "IMPROVEMENTS IN SCREW
PROPELLERS, AND IN SHIPS OR VESSELS.'
PROVISIONAL SPECIFICATION left by the said Edmund Hunt at the
Office of the Commissioners of Patents, with his Petition, on the
21st November 1854.
I, EDMUND HUNT, of Glasgow, in the County of Lanark, North Britain,
Gentleman, do hereby declare the nature of my said Invention of "IMPROVE-
MENTS IN SCREW PROPELLERS, AND IN SHIP3 OR VESSELS," to be as follows, that
is to say:-
This Invention relates to various modifications of screws or oblique-bladed
propellers to be used in the propulsion of ships or vessels in water, and to a
mode or modes of constructing ships or vessels, so as to render, them more
suitable for screw propulsion; a portion of these improvements being also
applicable to paddle steamers, sailing ships, and other vessels.
The first head of the Invention relates to the shape and configuration of the
blades of screw propellers, and consists_in_the_using-such-portions-of-helical
propelling surfaces as that the outer portions of the blades will be in advance
of the central portions thereof; in other words, the new form of blade is of such
A

page_text: a shape, that if a plane at right angles to the axis is made to intersect the
longitudinal centre of the central part, 'a larger portion of the outer part of
the blade will lie in front of such intersecting plane. Thus, for example, the
blade may be made to consist of such a portion of a helical surface as will lie
between two conical or spherical surfaces, placed with their apices or con-
vexities towards the after part of the propellor, and with their axes coincident
with that of the propellor; any kind of helical surface may be adopted for the
propellor, but it is preferred to use such a form that the intersection of a
plane passing through the axis with the blade will be curved or inclined
backwards. In some cases, as, for example, where the space allotted to the
propellor does not admit of the outer portions being in advance of the central
parts, the objects of the Invention may to some extent be carried out. by
employing blades consisting of portions of helical surfaces, of which the radial
generatrices are curved backwards, the blades being so shaped, that if a plane
passing through the axis is made to intersect the blade through the longi-
tudinal centre at the central part, the greater portion of the blade will lie to
that side of the intersecting plane which corresponds to the entering edge of
the blade, although the outer portion of the blade may not be more advanced
than the central part, and in some cases, indeed, not so far advanced. In all
cases, however, it is preferred to have the outer portions as far advanced as
possible within reasonable limits. It is also preferred to employ helical
surfaces produced by a curved or partly curved radial generatrix of such a
kind that no part of the acting surface of the blades shall be inclined outwards
to a greater extent than that of a right helical surface.
The second head of this Invention relates to the construction of flexible-
bladed screw propellers, and is applicable to the common form of screw, to
the improved form, described under the first head of this Invention, and to
other forms. This description of propeller blade consists of metal ribs com-
Lined with caoutchouc or other suitable-flexible material, such material filling
up the spaces between the ribs, and forming the acting surfaces. The ribs are
wrought-iron rods, each set of two or more (according to the number of blades
of which the propeller is made to consist) being made in one piece, with a
'central boss, formed with an eye, and carried by the propeller shaft. Two or
more such bosses with their radiating ribs make up the propeller, and a
portion of the present improvements consists in separating the bosses, and inter-
posing caoutchouc rings or any other suitable description of springs between
each boss. In addition, the rib bosses may be fitted-on-the shaft. with inclined
feathers and grooves, or screw threads. The objects of these contrivances is to
relieve the outer portions of the blades from strain or excessive stretching; for,
:

page_text: according to this improved plan, when the blades assume a finer pitch, the rib
bosses approach each other, thereby contracting the length of the blade as
measured on the shaft; and it is obvious, that on the pitch becoming finer,
the same amount of material will not require to stretch so much when the
length of the blade is reduced as when this length remains the same in all
pitches.
The third head of this Invention relates to various modifications of con-
trivances for effecting the swivelling of oblique-bladed propellers. The blades
of such propellers may either be solid, and formed with shanks, fitting into.
sockets in the boss; or they may themselves be formed with socket holes, so as
to be carried upon spindles projecting from the boss, and the boss may either
be formed or fixed upon the. shaft, or it may be capable of turning upon it.
The blades have bevil wheels formed or fixed upon their necks, and these
bevil wheels gear with a bevil wheel carried on the shaft or otherwise. The
driving bevil. wheel, or that by which, the. blades are swivelled, is, according to
one modification, formed or fixed-on the end of a tubular shaft enveloping the
main shaft, upon which, according to this modification, the propeller boss is
fixed, and this tubular shaft passes to the interior of the vessel. The central
propeller shaft is in a line with that driven by the engine; it is not, however,
fixed, but is connected to it by a coupling. This coupling is made capable of
sliding longitudinally upon the engine shaft, but is fitted on it with a feather
or otherwise, so as to be turned by it; whilst its 'other end is formed with a
screw thread, a corresponding screw thread being cut upon the central pro-
peller shaft at a short distance from the coupling, and upon the propeller shaft
is fixed a ring, serving as a back stop to a spring interposed between it and
the coupling, the spring being composed of any suitable material, as, for
example, a cylinder of caoutchouc encompassed by metal rings; precisely the
same effect will be obtained if the coupling is inserted, so as to put the screwed
part and the spring upon the engine shaft, the shafts being formed to corre-
spond. The tubular shaft is connected to the engine shaft, so as to be turned
by it. On the engine shaft revolving, the motion will not be immediately
communicated to the central propeller shaft, on account of the resistance of
the water to the rotation of the propeller, and the spring will yield and be
compressed, until its resistance balances that of the water, after which the
whole will revolve as a solid mass. The action of the spring coupling thus
occasions, a slight rotation of the tubular shaft about the central shaft, this
causing the blades to swivel by means of the bevil gear; and it is obvious, that
if the spring and-the-other-details-are-suitably-proportioned, the blades will
assume tlie-most efficient inclination. When the engine stops, the spring will
©)

page_text: expand and act on the coupling, so as to turn either the tubular or the central
shaft, thereby bringing back the blades into their normal position fore and
aft the vessel. In case the action of the screw coupling proves defective, on
account of internal friction, anti-friction balls may be interposed between the
rubbing surfaces, or anti-friction pulleys may be carried by the shafts for
the coupling to bear against. A contrivance similar to that which is used
for shifting ordinary clutch boxes may be adapted to the screw coupling for
shifting it by hand, so as thereby to set the propeller blades to any angle inde-.
pendently of the spring, and the spring may be dispensed with if it is thought,
desirable to set the blades by hand on all occasions;, or the spring may be.
"applied in a different manner, as, for example, by attaching it to some, fixed.
part of the vessel, and causing it to act on the coupling through the shifting.
lever or other detail. According to a slight modification of the arrangements'
just described, the shaft of the driving bevil wheel for swivelling the blades
may be made to pass through the centre of the main propeller shaft on which,
the boss is formed, and in this case the bevil wheels on the blades may be,
arranged either in the centre of the boss, hollowed for the purpose, or outside
the boss, (being covered nevertheless by an external casing.) In the latter.
case the driving bevil wheel will necessarily be behind, the propeller, and
intermediate bevil wheels will be required to transmit the motion to the blades
in the proper direction. According to another modification, the boss is made
capable of turning upon the shaft to a certain extent, limited by stops, and the,
bevil wheels on the necks of the blades are in gear with a bevil wheel fast
upon the shaft. In their normal position, the blades lie fore and aft the
vessel, but when the propeller is put in motion it turns upon its shaft up to
-the stop, thereby swivelling the blades to the angle regulated by the position of
the stop. If the propeller is drawn through the water when the engines are
stopped, it will turn upou its shaft, thereby returning the blades to their normal
position; or, instead of the stops on the shaft, the boss may be connected by
means of a tubular shaft, or otherwise-with-a-spring-or-with-adjusting gear,
either before or abaft the propeller; or, again, the boss may be fitted upon the
shaft with inclined grooves and feathers or stops, so as when turning upon it to
have at the same time a slight longitudinal movement, whereby it compresses
a spring. According to a further modification, the longitudinal movement may
be arranged to take place in opposition to the longitudinal thrust of the pro-
peller, thus taking advantage of the thrust as a species of spring power for
regulating the the inclination of the blades. In cases where the propeller
moves longitudinally-upon the shaft, the driving bevil wheel must be so con-
nectedto it as to traverse with it, being, however, all the while so connected to

page_text: the shaft as not to turn about it. The pressure on the blades may also be
taken advantage of in the following manner for regulating the obliquity of
their position:-The boss may be arranged to turn on the shaft (without moving
longitudinally, however,) the blades being turned by the action of a bevil
wheel fixed on the shaft. The blades must be constructed with their swivelling
axis dividing them unequally, so as to make the pressure of the water pre-
ponderate on one side. This preponderance of the pressure will tend to swivel
the blades, and it must be made to act in the opposite direction to the force
which tends to swivel them by means of the bevil wheels on the propellers
turning round its shaft; the blades will then assume the position in which
they are equally acted upon in both directions; and it is obvious, that if the
details are suitably proportioned, this position will coincide with that of the
greatest efficiency. In some of the modifications of swivelling-bladed pro-
pellers described under this head of the Invention, the swivelling gear may be
applied abaft the propeller instead of before it. In all cases the driving bevil
bevil wheel may be connected to the engine shaft, or other detail by which it is
actuated, by a spring of such a strength as to yield to a force greater than that
which will just overcome the friction of the parts, so that any sudden jerk will
not take effect upon the teeth of the bevil wheels; or the bevil wheels may
be superseded by chains or cords of wire, or other suitable material, and
grooved collars or pulleys. It is proposed to cover the bosses of the swivelling
bladed propellers with casings, the spaces in which are to be filled with
Jubricating matter of such a substance as not to ooze out, and which may be
mixed with some suitable ingredient rendering its specific gravity as great as
that of sea water, so that it may have no tendency to rise to the surface.
The fourth head of this Invention relates to such of the modifications of
propeller, described under the second and third heads of the Invention, as are
capable of assuming different pitches, in obedience to the variations in the
resisting action of the water; and consists in connecting such propellers with
the throttle or expansion valve of the driving engines, so that when greater
resistance is met with, and the pitch of the propeller becomes finer, more
steam may be admitted to the engines to enable them to maintain their rate;
whilst, on the other hand, if the resistance is reduced, in consequence, for
example, of the propeller being out of the water, the supply of steam may be
instantly diminished, the engines being thereby prevented from running

page_text: bow of the vessel. This rudder may be hung in any convenient manner, but
it is preferred to arrange it with its axis of vibration at or near its front edge:
The rudder may either be carried by a rudder post, which will. answer as a
front guard, or a guard frame may be fitted up in advance of its front edge:
It is obvious that the rudders of screw vessels with single sterns may be
arranged in the same way;
The sixth head of this Invention relates to the general shape of sea-going
vessels, more particularly screw steamers, the main object being the obtain-
ment of a cleaner run or stern than is at present given to such vessels. In
proceeding to design a vessel according to this plan, the length and depth
being determined, the parallelogram of like dimensions is taken, and an arc of
a circle or other suitable curve is drawn tangentially to the lower side thereof,
commencing from a point as far forward as may be, and running up quite
above the water level at the stern. This curve defines the depth of the body
of the vessel along the longitudinal centre line. Next, the plan or outline of
greatest width as projected upon a horizontal plane is chosen, it being pre-
ferred to, design this, outline so that the centre of the immersed bulk of the
vessel may lie in or near the longitudinal centre of the vessel at the water line.
The corresponding line; defining the heights of the greatest widths measured
on transverse. vertical planes at different points in the vessel's length, is deli-
neated on the vertical longitudinal plane, and a series of vertical lines are
drawn, corresponding to the ship's frames, or to transverse vertical sections,
corresponding transverse lines being also drawn on the plan. "The greatest
transverse vertical section is then designed, and the parallelogram circum-
scribing it is divided by any convenient number of horizontal & vertical
lines set at regular distances apart. In proceeding to design the.after portion
of the vessel, each transverse sectional outline is obtained by dividing the
respective circumscribing parallelograms by the same number of horizontal.
and vertical lines as in the main section, all--the horizontal lines being set
regularly apart, and all the vertical lines also, without reference to the varying
proportions between the horizontal and vertical dimensions of the parallel-
ograms. The sectional outlines are then traced on the various sections so as in
each case to intersect the divisional lines, in precisely the same manner as
the main outline intersects the divisional lines upon its circumscribing parallel-
ograms. By these means a flat or convex run will be obtained, which will
gradually rise, until at. the-stern-it-will run-up-above the water line, and this
description of run is preferred, às it admits of the freer access of the water to
the propeller. This form is also deemed advantageous for paddle steamers. and
sailing vessels... If, the greatest transverse section-is a semicircle, the other

page_text: sections will, by the geometrical construction, be semi-ellipses, and may be
drawn directly on determining the two axis, in each case no further construc-
tion being required. The process described, however, is applicable to any kind
of transverse sectional outline. Vessels with the ordinary form of run may be
designed in the same way, it being merely necessary to add to each transverse
section a couple of concave curves, tangential to the vertical centre line and to
the outline previously obtained, in the manner herein-before; described. A
modification of the same geometrical process may also be employed in design-
ing the forward part of the vessel. The parallelograms circumscribing the
several transverse sections are divided vertically and horizontally by the same
number of lines as on the greatest or main transverse section, but instead of
being divided equally, the ratios. between the horizontal divisions are gradually
and regularly varied towards the stern of the vessel, the vertical divisions being
equal, or the vertical divisions may be varied, the horizontal ones being equal;
or, again, both the vertical and horizontal divisions may be varied. The
degrees of variation in the divisional ratios will depend on the description of
bow to be given to the vessel; whether it is to have concave or convex lines,
for example, the divisional ratios requiring to be more rapidly varied in the
latter case.
The circumscribing parallelograms of the several sections being
thus divided, points intersection are marked in the spaces corresponding to the
spaces on the main section through which the main outline passes, and a curve
is drawn through these points of intersection in each case, such curve being
the outline of the vessel at the respective section. This geometrical process,
as also that described for designing the after. portion of the vessel, will neces+
sarily give a series of outlines, so related to each other, as to produce a form of
vessel of which all sectional outlines, both vertical and horizontal, will blend
harmoniously together, whilst at the same time the general proportions of the
vessel may be selected at the pleasure of the designer
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edmund Hunt in the Great Seal Patent Office on the
21st May 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDMUND
HUNT, of Glasgow, in the County of Lanark, North Britain, Gentleman, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of November, in the year of our Lord

page_text: One thousand eiglit hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Edmund Hunt, Her special license that I, the said Edmund Hunt,
my executors, administrators, and assigns, or such others as I; the said Edmund
Hunt, my executors, administrators, or 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, usc, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, 'the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN SCREW PRO-
PELLERS, AND IN SHIPS OR VESSELS," upon the condition (amongst others) that I,
the said Edmund Hunt, 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 : Edmund Hunt, do hereby declare the
nature of my 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 in writing, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say:-
My said. Invention relates to various improved modifications of screw or
oblique-bladed propellers to be used in the propulsion of ships or vessels in
water, so as to obtain a better propelling effect than has hitherto been secured
by means of propellers' of this class; and to a mode or modes of constructing
ships or vessels, so as to render them more suitable for screw propulsion; a
portion of these improvements being also applicable to paddle steamers, sailing
ships, and other vessels.
And in order that my said Invention may be properly understood, I have
appended hereunto four Sheets of explanatory Drawings, to which I shall
herein-after refer, by means of figures and letters of reference, as I proceed
with the description of my said Invention; and furthermore, in order that the
portion of my said Invention which relates to screw or oblique-bladed pro-
pellers may be distinctly intelligible, I shall first proceed to indicate the
precise meanings which I attach to certain of the technical terms herein-after
used by me.
Thus, I consider that a helix is a line generated by, or the path of, a point,
which has had imparted to it a longitudinal motion combined with a rotatory
motion about an axis. A helical or screw surface is a surface generated by,
or the path of, a line, which has had imparted to it a longitudinal motion com-

page_text: bined with a rotatory motion about an axis. True helices and helical or screw
surfaces are such as are generated by uniform longitudinal and rotatory
motion, and in them the pitch or longitudinal distance traversed by the genera-
ting point or line during each revolution or portion of a revolution is uniform
throughout. In differential helices and screws, the pitch or longitudinal
motion either increases or diininishes in rate, as compared with the rotatory
motion. False screws, sometimes called expanding or contracting pitch screws,
are those in which the inclinations of portions of their surfaces, taken at
different distances from the axis, correspond to different pitches. Every true
helical surface may be considered as generated by any one of a variety of lines,
for if any section whatever is taken of a helical surface so as to extend from
the axis to the circumference, the line of intersection will always be such as
will generate the same surface if the same generating motion is imparted to
it. When not otherwise expressed, however, I shall use the terms "generating
line or "generatrix" to signify the line corresponding to the intersection
with the helical surface in question of a plane radiating from or passing
through the axis: A screw has a right belical surface when its radial gene-
ratrix is a straight line at right angles to the axis, as in the common screw.
When the length of a screw blade or of any part of a screw blade is men-
tioned, it is to be understood as measured or projected on a line or surface
parallel with the axis, unless otherwise specially expressed.
The first head of my Invention relates to the shape and configuration of the
blades of screw propellers, and consists in using such portions of helical pro-
pelling surfaces as that the outer portions of the blades will be in advance of
the central portions thereof, as viewed laterally. This new form of blade is of
such a shape, that if a plane at right angles to the axis of the propeller is made
to intersect the longitudinal centre of the central part or parts of the blade,
meeting or joining the boss, a larger portion of the outer part of the blade will
lie in front of such intersecting plane. Thus, for example, the blade may be
made to consist of such a portion of a helical surface as will lie between two
conical, spherical, or curved surfaces, placed with their apices or convexities
towards the after part of the propeller, and with their common axis coincident
with that of the propeller. The propelling surface of the blade may be a right
helical surface of the ordinary kind, but I prefer to use such a form that the
radial generatrix thereof, or the intersection therewith of a plane passing
through the axis of the propeller, will be curved or inclined backwards, and
in-all-cases_I_use_a_helical_propelling_surface_of_such_a_kind_that_no_
part of such surface-is-inclined-outwards- to a-greater-extent than a right
surface is in other words
Tuse
holical neonelling surface she

page_text: ‚radial generatrix of which makes an acute angle with the axis on the
acting" side.
Figure 1, on Sheet of the explanatory Drawings hereunto attached,
représents, in side and back elevation; the latter as looking on the acting face;
one modification of my improved screw propeller. The dotted lines a, a, are
continuations of the helical outlines of the circumferential edges of the blades
the propelling surfaces of which are such as would be generated by the dotted
lines b, b, at right angles to the axis or shaft, that is to say, the propelling
surfaces are right lielical surfaces, like those of the cominon screw; but instead
of, as in the common screw, having their radial or entering and back edges cut
down straight to the shaft, as it were, these edges are such às are obtained or
defined by the intersections with the helical surfaces of two cones, indicated by
the dotted lines b, d, b, and e, f, e; the former defining the front or entering
edges of the blades, and the latter the back edges. In this manner a form of
blade is obtained which has its outer portion A thrown in advance of the
central part B, whilst at the same time the acting surface is such as is derived
from the same generatrix as that of the common screw, and the blade is of
uniform axial length at all distances from the axis, as in the common screw. I
do not propose, however, to make the axial length of the blade thus uniform in
all cases, but it may be 'increased towards the axis, as in the modifications
represented in Figures 3, 4, 5, and 6, on Sheet 1 of the Drawings; nor do I in
all cases employ precisely similar cones or convex surfaces for defining both the
front and back radial edges of the blade, so long as the outer portion is thrown
in advance, and the front or entering edge is inclined forward. The object of
throwing the outer portion of the blade in advance, in the manner described,
is to place it out of the range of the disturbing or centrifugal action of the
central part, that is to say, so that the outer part, which I consider to be
the most effective portion of the blade, may act on water in advance of that
which I consider to be disturbed by the centrifugal action of the central part.
Figure 2, on Sheet 1 of the Drawings, represents, in side and back elevation,
the latter as looking on the acting face, another modification of my improved
screw propeller. I may here remark that on Sheet 1 of the Drawings,
corresponding parts are in all the Figures indicated by the same letters of
reference. In the modification, represented in Figure 2 on the said Sheet, the
outer portions. A of the blades are thrown forward in advance of the central
part B to about the same extent as in the modification represented in Figure 1
on the same Sheet; but instead of the helical propelling surface being similar
to that of the common screw, it is such as may be said to be generated by
the inclined dotted line of radial generatrix c, b. "This construction gives the

page_text: acting surface of the blade a more concave or hollowed form, which is adopted
in order to counteract the centrifugal or divergent action of the blade on the
water. I'may here remark, that screw propellers, the acting surfaces of which
have been such as would be generated by an inclined line, such as c, b, have
already been tried; but the blades of such propellers have, as I understand,
had their front and back radial edges so formed as to lie in planes passing
through the shaft, or they have been of such a shape that the central parts
were in advance of the outer portions. Now, I consider that this arrangement
would throw the outer portions of the blades still more into the path or range
of the disturbed water thrown out by the central part, and that in consequence
any improved action that might be expected from the backward inclination-of
the propelling surface would be neutralised by the increased disturbing " action
of the central part of the blade; whereas, according to my improved "com-
bination, the advantages to be expected from the backward inclination of the
propelling surface cannot be lessened by the counteracting centrifugal action.
Figure 3, on Sheet 1 of the Drawings, represents, in 'side and bäck elevation;
the latter as looking on the acting face, a-modification of my improved "screw
propeller, which differs from that represented in Figure 2 on the same Sheet:
first, in having a slightly increasing axial length of blade towards the centre';
secondly, in having three blades instead of two, regarding which I may remark
that I do not confine myself to any particular number of blades; and, thirdly,
in having propelling surfaces, such as may be said to be generated by the
curved radial generatrix c, b, which is concave on the side corresponding to
the acting face. Figure 4, on Sheet 1 of the Drawings, represents, in side and
back elevation, the latter as looking on the acting face, a further modification
of iny improved screw propeller. In this modification the propelling surface is
such as corresponds to the curved generatrix c, b, which, whilst it is convex on
the side corresponding to the acting face, has no part which does not on that
side make an acute angle with the axis. The outer portion of this propelling
surface approaches a right helical surface, like that of the common screw, but
it is more and more inclined backwards as it nears the axis. I prefer this
kind of propelling surface for full or high powered steamers, whilst I prefer
such a propelling surface as I have described in reference to Figure 3, on
Sheet 1 of the Drawings, for vessels in which auxiliary or small power is used.
The front and back radial edges of the blades of the modification of propeller
represented in Figure 4 on Sheet 1 of the Drawings are such as would lie on
the curved conoidal surfaces, indicated by the dotted curved lines b, d, b, and
efe; but, as already mentioned, the precise outline of the front and back
radial edges of the blades may be varied in many ways, it being essential,

page_text: however, that they are in all cases inclined forward. In some cases, as for
example, where the space allotted to the propeller does not admit of the outer
portions of the blades being forward of the central parts, as viewed laterally,
the objects of my Invention may to some extent be carried out by employing
blades consisting of portions of helical propelling surfaces, of which the radial
generatrices are curved considerably backwards, the blades being so shaped
that a plane passing through the axis and through the longitudinal centre of
the central part, or part meeting or joining the boss, will divide the blade
unequally, the greater portion lying on the side of the intersecting plane,
.corresponding to the entering edge of the blade; in other words, the front and
back edges of the blades are to be defined by surfaces, the intersections of which,
with planes passing through the axis, make less acute angles with the axis than
the generatrix. These conditions may be fulfilled in some cases without having
the outer portions of the blade in advance, as viewed laterally, whilst in other
cases again they may be fulfilled without having the outer portions of the blade
so far advanced, viewed laterally, as the central part. An example of the
former class of cases is given in Figure 5, on Sheet 1 of the Drawings, whilst
an example of the latter class of cases is given in Figure 6 on the same Sheet.
In both these examples the generatrix of the propeller surface is similar to that
of the modification represented in Figure 4 on the same Sheet, that is to say,
its backward inclination gradually increases as it approaches the axis, and it
is only the combination of this particular kind of generatrix with the dispo-
sition of the front and back edges, as described in reference to Figures 5 and 6
on Sheet 1 of the Drawings, that I claim as the part of my Invention which
has reference to such disposition of the front and back edges. I prefer in all
cases to have the outer portions of the propeller blades as much in advance as
possible within reasonable limits, and this part of my Invention applies either
to propellers with fixed or with moveable blades, or with proportionately small
or large bosses; though I prefer small bosses; but I disclaim the application of
-my-advance-blade-system to any screw or oblique-bladed propeller, in which the
intersection of the propelling surface with a plane passing through the axis is
a-line forming an obtuse angle with the axis on the acting side, unless the degree
of obtuseness is so slight as to have no practical effect. The screws repre-
sented on Sheet 1 of the Drawings are each supposed to be of uniform pitch;
but it will be obvious to the practical man that the portion of my Invention
described under this, the first head thereof, is equally applicable to increasing
pitch screws, and to screws combining both_an_increasing and an expanding
pitch. (See paragraph at the end of the second head).
The second head of my Invention relates to the construction of flexible-

page_text: bladed screw or oblique propellers, and is applicable to the, common form of.
screw, to the improved form described under the first head of my Invention,
and to other forms. This kind of propeller is represented, on Sheet 2. of' the
explanatory Drawings hereunto attached, as divested of the external flexible
covering, to which covering my present Invention has no reference. Figuró 7.
on the said Sheet is an end view, and Figures 8 and 9 are side views, of a
modification; corresponding to the common form of screw propeller; whilst
Figure 10 is a side view, Figure 11 an end view, and Figure 12 another side
view, of a modification, corresponding to one of the improved forms of screw
propellers, described under the first head of my Invention. The kind of pro-
peller blade to which this portion. of my Invention refers consists of metal
ribs A, combined with caoutchouc .or other suitable flexible material, such
material filling up the spaces between the ribs, and forming the external
covering and acting surface. The ribs A are wrought-iron rods, each set of.
two or more (according to the number of blades of which the propeller is.
made to consist) being made in one piece, with a central boss B; formed withi
an eye, and carried by, the propeller shaft C. Two or more such bosses
with their radiating or curved ribs make up the propeller, and a portion of my.
present Invention consists in separating the bosses and interposing caoutchouc
rings D, or any other suitable kind of springs, between each boss B.. In
addition, the rib bosses may be fitted on the shaft with inclined feathers and
grooves or screw threads, as at E; in Figure 10. The object of these con-
trivances is to relieve the outer portions of the, blades from strain or excessive.
stretching; for, according to this improved plan, when the blades assume a'
finer pitch, which their flexibility enables them to do on certain occasions, the.
rib bosses approach each other, as represented in Figures 9 and 12, thereby.
contracting the axial length of the blade; and it is obvious, that on the pitch:
becoming finer, a certain amount of material will not require to stretch so
much if the axial length of the blade is reduced, as it would were the axial
length to remain the same, notwithstanding the alteration in the pitch. When
a propeller of this kind is at rest, the ribs assume positions in a-line with the
shaft, as represented in Figures 8 and 10; but when the propeller is caused to
revolve, the after portions of the blades become twisted round the shaft, and
the ribs assume positions such as are indicated in Figures 9, 11 and 12, on
Sheet 2 of the Drawings hereunto attached. (The dotted lines g, in Figures
2, 3, and 4, on Sheet 1 of the Drawings indicate the intersections with the
propelling surfaces of planes at right angles to the shafts, and correspond to
-the-outlines-of-the-sections_or_thicknesses of wood, of which the patterns used

page_text: in casting the propellers are built up. This last remark refers to the first head
of the Invention.)
:
The third head of my Invention relates to various modifications of con
trivances for effecting the swivelling of the blades of oblique-bladed propellers,
and certain of these modifications and details connected with them are
represented in Figures 13 to 17, on Sheet 2, and Figures 18 to 31, on Sheet 3,
of the explanatory Drawings hereunto attached. Figure 13 is a transverse
vertical partial section. Figure 14 is a longitudinal partial section, and
Figure 16 is a side elevation; of one modification of swivelling bladed oblique
propeller; the latter Figure representing the blades in their acting positions,
and the former two Figures representing them as at rest. Figure 15 is.a
longitudinal.section..of one modification of my contrivances for swivelling the
propeller blades; and Figure 17 is a longitudinal partial section of another
modification of such.. contrivances. Figures 18 and. 19 are respectively
transverse and longitudinal vertical partial sections of another modification of
my swivelling bladed propeller. Figure 20 is a longitudinal section of a
further modification of my swivelling contrivances; and Figures 21, 22,
and 23 are views explanatory of certain modifications of the minor details
of my swivelling contrivances... Figures 24 to 31 are sections of various
modifications of my swivelling-bladed, propellers, and will be hercin-after. more
particularly referred to: The several arrows indicate the direction in which
the several propellers are to be turned for propelling ahead, and the bow
of the vessel is supposed to be towards the right-hand side of each Figure.
The blades A of my improved swivelling-bladed propellers may either be
solid, and formed with. shanks B, fitting. into sockets in the boss C, as in the
modifications, represented in Figures 24 and 25, or they may themselves - be
formed with socket holes, so as to be carried upon spindles or arms -D,
projecting from the boss C, as in the modifications represented in Figures
13, 14, 18, 19, 26, 27, 28, and 30, and the boss C may either be formed or
fixed upon the propeller shaft E, as in the modifications-represented-in-Figures
13, 14, 18, 19, 24, 25, 30, and. 31, or it may be capable of turning upon
it, as in the modifications represented in Figures 26, 27, 28, and 29. The
blades A have bevil wheels F formed or fixed upon their necks or shanks,
and these bevil wheels gear, with a bevil wheel G, carried on the shaft E, or
otherwise. The driving bevil wheel G, or that by which the blades are
swivelled, is, according to one modification, formed or fixed on the end of a
tubular shaft H, enveloping the propeller shaft E, upon which, according to
this modification, the-propeller-boss C is fixed, and this. tubular shaft H passes

page_text: to the interior of the vessel. The propeller shaft E'is in a line with the
shaft I, driven by the engine; it is not, however, fixed to it; but is connected
to it by a coupling J. This coupling is made capable of sliding longitudinally
upon the engine shaft. I, but it is fitted on it with a feather K, as represented in
Figure 15, or otherwise, so as to be turned by it, whilst its other end.is-formed
with a 'screw thread, a corresponding screw thread L (Figure 15)- being cut
upon the propeller shaft E. At a short distance from the coupling J, and upon
the propeller shaft E, is fixed a ring M, serving as a back stop to a spring 'N,
interposed between it and the coupling J, the spring being composed of any
suitable material, as, for example, a cylinder of caoutchouc N, encompassed-by
metal rings. Precisely the same effect will be obtained if the coupling J. is
inverted, so as to put the screwed part and the spring upon the engine shaft.I,
the shafts being of course suitably modified to. correspond; or, the feather or
groove on the engine shaft I, or on the corresponding end of the coupling J;
may be more or less inclined in the opposite direction to the screw thread,
or its equivalent, on the propeller shaft E. The tubular shaft H. is connected
to the engine shaft I, so as to be turned by the latter.. This connection may
be effected in various ways, as, for example, by means of a cylindrical box or
frame O. (Figure 15), fixed to the tubular shaft H, and formed with grooves, in
which projections Pupon the coupling J can slide, and as this coupling..turns
with the engine shaft I, as already described, it will communicate the rotatory
motion of the latter to the shaft H, by means of the box or frame O. On the
engine shaft I being made. to revalve; the.. motion. will not be immediately
communicated to the propeller shaft. E, on account. of the resistance of, the
water to the rotation of the propeller, and the spring N will yield and be
compressed by the coupling. J; which will screw itself upon the shaft. E, against
the spring N, until the resistance of this: spring balances that. of.the.water;
after which the whole will revolve as a solid mass. The tubular shaft H,
being connected to the engine shaft I, the action of the spring coupling.J
will obviously occasion a slight rotation of the former. about the propeller
shaft E,.and this will, cause the propeller blades A to swivel, by means of the
bevil gear F, G; and it is further obvious, that if the spring, N and the other.
details are suitably proportioned; the blades A will assume the most efficient
inclination, or the position in which they act, most, efficiently. When the
engine stops, the spring N will expand and act on the coupling J, so as to
turn either the tubular shaft H or the propeller shaft E, thereby bringing
back the blades A into their normal position fore and aft the vessel.
case the action of the screw.coupling J. proves defective, on account of internal
friction anti-friction balls may be'interposed between the rubbing surfaces; in
In

page_text: the manner, for example, represented in Figure 21, which is a transverse section
of the coupling J and shaft E, as modified in shape' to suit the application of
the anti-friction balls R'between their rubbing surfaces; or anti-friction
pulleys may be carried by the shafts E and I for the coupling to bear, against;
as in the modification represented in Figure 17. Here the anti-friction pulleys
S are carried upon pins T, projecting from the shafts I and, E in 'such a manner
as to respectively suit the longitudinál grooves or slots U, at one end of, the
coupling J, and the helical or screw grooves: or slots .V, at the 'other end
thereof. The spring may be applied to this coupling in any of the ways
herein described, but in Figure 17 another mode of applying it is also shewn.
The pins T on the propeller shaft E are made to project considerably through
the screw grooves V in the coupling J, and are entered into the short external
cylinder W, which serves as the back stop for the spring N, and corresponds
to the ring M,' in the modification represented in Figure 15. The other end
of the spring N acts on a ring or collar X upon the coupling J, and the
spring being thus outside the coupling J, this coupling can be connected directly
to the tubular shaft H, for the purpose herein-before explained, this connection
being effected in this instance by means of projections Y on the shaft H, and
working in grooves in the inside of the coupling J, thus allowing for the longi
tudinal traverse of the latter. In this modification, the spring N acts in a
different direction to that of the modification represented in Figure 15; but this
is unimportant, provided the screw grooves and other details are modified to suit
the direction in which the propeller blades A are to swivel. In Figure 20 is
represented another modification of my screw coupling, in which the anti-friction
pulleys S are carried I upon pins T, fixed or formed in the inside of the coupling
Jyand these pulleys work in grooves in the shafts I and E. In this instance,
the spring N is applied in the same manner as in the modification represented
in Figure 15; or, instead of either of the plans indicated in Figures 17 and 20,
the pulleys S may be detached from both the coupling J and the shafts I and E;
and may be applied instead, in the same manner as the balls, as herein-before
described in reference to Figure 21. For example, they may be applied as
represented in Figure 22, which is a transverse section of the coupling J and
shaft E, as suitably modified in shape, the pulleys S so applied being kept in
their proper positions by being carried in light frames Z, as represented in
elevation and plan in Figure 23. A contrivance similar to that which is used
for shifting ordinary clutch boxes, and consisting, for example, of a forked
lever (Figure 15), connected to a ring b, carried in a groove on the outside.
of the coupling J; the lever being actuated in any convenient manner, may be
employed for shifting tlie coupling by hand, so as thereby to set the propeller

page_text: blades Á to any angle independently of the spring N, and this spring may
be dispensed with if it is thought desirable to set the blades by hand on
all occasions; or the spring may be applied in a different manner; as, for
example, by attaching it to some fixed part of the vessel, and causing it to act
on the coupling through the shifting lever a, or any other suitable connection.
Plates or annular discs c'are applied between one end of the spring N'and
either of the rings or plates between which the spring acts; and this plate can
be adjusted by means of screws d, so as to regulate or modify the action of the
spring: According to a slight modification of the arrangements just described,
tlie shaft H of the driving bevil wheel G for swivelling the blades A. may be
made to pass through the centre of the propeller shaft E; as represented in
Figures 18, 19, 20, and 24, the inner, end of the shaft H being squared and
fitted into a square recess in the end of the engine shaft I, so as to turn withi
this shaft. In this case the bevil wheels F on the blades A may be arranged
either in the centre of the boss C, hollowed for the purpose, as in the modi-
fication represented in Figure 24, or on the outside of the boss, as in the
modification represented in Figures 18; 19, and 20, (being covered, nevertheless,
in this latter case with an external shell or casing m.). In the latter case, the
driving bevil wheel G will necessarily be behind the propeller, and interme-
diate bevil wheels e will be required to transmit the motion of the blades in
the proper direction, these bevil wheels e being carried loosely on studs f pro-
jecting from the sides of the boss C, and being of such a size as to gear with
both the bevil wheels F and G, which are just clear of each other. I may
here remark, that when the propeller is turned, so as to back the vessel, the
spring N does not act, but the coupling J leaves it, and traverses on the shafts.
E and I, until it reaches a collar or stop g, according to the modifications' re-
presented in Figures 15 and 20, or until it brings up against-the projections Y,
on the shaft H, the inner ends of the grooves in which these projections work.
This traverse of 'the coupling of course causes the blades to swivel, and the
length of traverse allowed for is such as corresponds to the amount of swivelling"
action required to bring the blades 'into the proper positions for backing the
vessel. According to another modification of my swivelling-bladed propeller,
represented in transverse and longitudinal section in Figures 26 and 27, the
boss C is made capable of turning upon the shaft E to a certain extent,
limited by stops h, and the bevil wheels F'on the necks of the blades A are
in gear with a bevil wheel G, fast upon the shaft, the coupling in the interior
of the vessel being in this instance dispensed with. In their normal positions
the-blades_A_lie_fore and aft the vessel, but when the propeller is put in
motion-the-hoss C.turns upon the shaft E. up to the ston h. thereby swivelling

page_text: the blades to the propelling angle, which being once attained is not variable,
as in my former modifications, being determined by the position of the stop
upon the shaft. If the propeller is drawn through the water when the engines
are stopped, it will turn upon its shaft, in consequence of the action of the
water upon the blades, thereby returning the blades to their normal positions;
or, instead of the stops on the shaft, the boss may be connected by means of
a tubular shaft or otherwise, with a spring or with adjusting gear, either
before or abaft the propeller; or, again, as in the modification represented in
longitudinal section in Figure 28, the boss C, or a prolongation i thereof, may be
fitted upon the shaft E, with inclined grooves and feathers, or stops, as at j, so
as when turning upon the shaft to have at the same time a slight longitudinal
movement, whereby it acts upon a spring. This spring may either be arranged
in a similar manner to those represented in Figures 15, 17, and 20, or it may
consist of a compound blade spring k, as represented in Figure 28, fixed, for
example, to some part of the vessel abaft the propeller, and connected to the
shaft or boss of the latter by means of a ring and groove, as at l. According to
a further modification, the longitudinal movement may be arranged to take place
in opposition to the longitudinal thrust of the propeller, thus taking advantage
of the thrust as a species of spring power for regulating the inclination of the
blades. Figure 28 may be taken to represent this modification, the spring k
being supposed to be removed, and the blades being supposed to be so set that
the shaft E will require to be turned in the contrary direction to that indicated
by the arrow when the vessel is to be propelled ahead. In cases where the
propeller boss C moves longitudinally upon the shaft, the driving bevil wheel
G must be so connected to it as to traverse with it, being, however, all the
while so connected to the shaft as not to turn about this last. Thus, for
example, whilst the bevil wheel G (Figure 28) is encompassed by the outer
shell or casing m of the boss, so as to be carried along longitudinally with the
boss, and be constantly in gear with the bevil wheels F; it is also connected to
the shaft E by a feather and groove, as at n, so as not to partake of the motion-
of the boss round about the shaft. In case the action of the thrust is not
sufficiently powerful to prevent the blades from being set round to too fine an
angle, or from being turned even beyond the position in which they are at right
angles to the shaft, a spring may be applied to act in concert with the thrust,
this spring, however, being much weaker than it would require to be if the
action of the thrust were not taken advantage of in the manner just described.
A mode of applying this auxiliary spring is indicated in red lines at p in
Figure 28. Referring back to the modification, the description of which-imme-
diately precedes that of the one last mentioned, I may here remark, that in

page_text: Any
turning the propeller, with the view of producing a backing effect, the primary
tendency will be to produce a thrust opposed to the longitudinal motion of
the boss on the shaft. If the action of this thrust is sufficient to prevent the
blades from reaching their backing position, they having to turn through rather
more than a quarter of a .circle for this purpose, it will be necessary to
lock the blades in the proper position when the vessel is to be backed.
suitable contrivance may be adopted for this purpose, but I have not delineated
any such contrivance in my Drawings, as I think it will not be required, or
that the details of the arrangement are susceptible of being proportioned in
such a manner that it will not be required. According to another modification,
represented in partial longitudinal section in Figure 29, the resisting or
reactionary pressure of the water upon the blades A of the propeller may be
taken advantage of for regulating their inclination by arranging the boss to
turn about the shaft E, (without moving longitudinally, however,) the blades
being turned by the action of a bevil wheel G, fixed or held upon the shaft.
The blades are constructed with their swivelling axis q dividing them un-
equally, so as to make the pressure of the water preponderate on one side,
the forward side in this instance. This preponderance of the pressure tends
to swivel the blades, and it acts in the opposite direction to the force which
tends to swivel them by means of the bevil wheels F, G. When the shaft is
turned, the resistance of the water holds back the propeller from turning
immediately with the shaft, and the bevil wheel G is consequently turned in
advance of the boss, and, acting on the bevil wheels F, swivels the blades.
Now, the direction in which this swivelling takes place is opposite to the
direction in which the preponderance on the forward parts of the blades tends
to swivel them, and the blades will assume the positions in which they are
equally acted upon in both directions; and it is obvious that, if the details are
suitably proportioned, the positions thus taken up will coincide with those of
most efficiency. When the kind of propeller represented in Figure 29 is.
turned for backing, a projection on the boss comes up to a stop s on the
shaft E, and the bevil wheel G, being free to move away from a stop t on the
shaft E, by which stop it is carried round when propelling ahead, the blades
swivel on their arms, by the action of the water pressure preponderating on
one side.
In some of the modifications of swivelling-bladed propellers, described under
this the third head of the Invention, the swivelling gear may be applied abaft
the propeller instead of before it. In all cases the driving bevil wheel G may
be connected to the engine shaft, or other detail by which it is actuated by a
spring, of such a strength as to yield to a force at all greater than that which

page_text: บ
will just overcome the friction of the parts, so that any sudden jerk or strain,
will not take effect upon the teeth of the bevil wheels; or the bevil wheels
F, G, may be superseded by chains or cords, or belts of wire, or other suitable
material, and grooved collars or pulleys, as represented in Figures 30 and 31.
In the modification represented in Figure 30% grooved pulleys F, G, are substi-
tuted for toothed bevil wheels, and an endless cord u is passed round the back
of the pulley G, thence 'round the front' of the pulley F on the neck of the
blade A; the cord next passes round the back of a carrier pulley v, loose upon
the shaft E, behind the propeller boss, after which it passes round the front,
of the pulley F on the neck of the lower blade; and finally reaches its starting
point at the back of the pulley G. The cord is pinned to the several pulleys,
as at iv, so that it cannot slip, and' it transmits the swivelling motion to the
blades with the same ease as the bevil wheels. A chain may obviously be sub-
stituted for the cord u with a similar effect. In the modification represented
in Figure 31, the pulleys F, G, and are made with plain-conical surfaces;
and two endless belts u, x, of rectangular section, are passed 'round them in a
similar manner to the cord in Figure 30. The belts 'u, x, are of such a shape
as to lie upon the surfaces of the conical pulleys, to each of which each belt
is pinned to prevent it from slipping. The two belts cross" each other at the
points where they go over from one' pulley to the other, the route of the outer
belt u u being exactly the same as that of the cord w'in Figure 30, whilst the inner
belt a passes round the half of each pulley opposite to the half round which
the belt u passes. The bosses of the several modifications of swivelling-bladed
propellers, described under this, the third head of the Invention, are covered by
an external shell or casing 'm, and it is proposed to fill the internal spaces with
lubricating matter of such a substance as" will not ooze out or admit the
entrance of water. Such lubricating matter may be mixed with some suitable
ingredient, rendering its specific gravity as great as that of sea water, so that
it may have no tendency to rise to the surface. Various contrivances may be
adopted for keeping the blades A upon their arms' D, but I prefer the one repre-
sented in Sheets 2 and 3 of the Drawings. In this contrivance a groove is
-turned-out-of-the arm D, and into this groove is fitted-a-loose- ring--which-is-
externally flush with the outer surface of the arm. This loose ring is put into
groove in two halves, and after the arm is inserted in the socket of the blade
A, screw pins are passed from the outside of the blade into the loose ring, so as
to fix this ring to the blade, and prevent the blades being drawn off the arm.
A similar contrivance is adopted in the modification represented in Figure 25
for connecting the two blades together, so that they cannot be drawn asunder.
Here the shank B of one of the blades A
les A is made tubular, and the shank of
the

page_text: the other blade fits into it, and has a loose ring fitted upon it at, this ring
being fixed to the shank of, the other, blade by pins, which are introduced
through a small hole in the boss, the blade. being turned round to bring the
pin holes in succession opposite to the hole in the boss. In the modification
represented in Figure 24, the blades are held to the boss by means of the bevil.
wheels F, which are in the hollowed centre of the boss, and these bevil wheels
are fixed upon the shanks B of the blades by cotters, z, or otherwise..
The fourth head of the Invention relates to such of the modifications of
propellers described under the second and third heads of the Invention as are
capable of assuming, different pitches in obedience to the variations in the.
resisting action of the water, and consists in connecting such propellers with
the throttle or expansion valve of the driving engines, so that when greater.
resistance, is met with, and the pitch or inclination of the propeller blades
becomes finer, more steam may be admitted to the engines to enable them to
maintain their rate; whilst, on the other hand, if the resistance is reduced, in
consequence, for example, of the propeller being out of the water, the supply
of steam may be instantly diminished, the engines being thereby prevented
from "running away." One mode of carrying out this part of my Invention
is represented in Figure 15, on Sheet 2 of the Drawings hereunto attached,,
and consists in connecting, a rod y to the coupling J, or to any detail partaking,
of the movements of the coupling, as, for example, the lever a, which rod y is
connected to the throttle or.expansion valve of the driving engines.
The fifth bead of the Invention relates to the rudders of screw. steamers,
being more particularly applicable to vessels with double sterns and two pro-.
pellers. The improvement consists in employing a single rudder placed at the
bow of the vessel, as represented in Figure 32, on Sheet, 4 of the Drawings
hereunto attached, this Figure being a side elevation of a vessel fitted with.
two keels A towards the stern, one of which keels is seen in the half plan;
Figure 33, and both of which.are seen in end elevation in Figure 35, also on
Sheet 4 of the Drawings. The vessel is represented as fitted with two screw
propellers. B,,C, one at each stern keel, which propellers being of comparatively
small diameter are placed as far forward as possible, and will give out all
the advantages; derivable from their position free from the counteracting and
impeding effect of a stern, rudder and rudder.. post. The rudder D may be.
hung in any convenient manner, but it is preferred to arrange it with its axis
of vibration at or near its front edge. The rudder may either be carried by a
rudder post, as at E, which post may answer as a front guard for it, or a guard
frame may be fitted up. in advance of its front edge. It is, obvious that the
rudders of screw vessels with single. stern keels may be arranged in the same.

page_text: way, that is to say, the rudders of such vessels may be placed at the the bow,
and may have the axis of vibration at or near the front edge.
The sixth head of the Invention relates to the general shape of sea-going
vessels, more particularly screw steamers, the main object being the obtain-
ment of a cleaner run or stern than has hitherto been given to such vessels.
This part of my Invention is illustrated by-Figures 32 to 43, on Sheet 4 of the
Drawings hereunto attached; Figure 32 being a side elevation, or sheer draft,
and Figure 33 a half-breadth plan; of a vessel designed according to my
improved system; whilst Figures 34 to 43 represent sundry transverse vertical:
sections, corresponding to Figures 32 and 33, a number of such transverse
vertical sections being combined in Figure 41 to shew the general effect. In
proceeding to design a vessel according to my improved system, the length and
depth being determined on, a parellelogram of like dimensions is taken, and an
arc of a circle or other suitable curve F, G, is drawn tangentially to the lower
side thereof, commencing as far forward as may be, and running up quite above
the water level W, L, at the stern. This curve F, G, defines the depth of the
body of the vessel along the longitudinal centre line. Next, the plan or outline
H, H, of greatest width of the body as projected on a horizontal plane, is
chosen; it being preferred to design this outline so that the centre of the
immersed bulk of the vessel may lie in or near the longitudinal centre of
the vessel at the water line W, L. The corresponding line h, h, defining the
heights of the greatest widths of the body as measured on transverse vertical
sections at different points in the vessel's length, is delineated on the side eleva-
tion Figure 32, and a series of vertical lines are drawn on this Figure 32, and
across the half-breadth plan Figure 33, corresponding to transverse vertical sec-
tions of the vessel. These vertical lines are in the diagrams (Figures 32 and 33)
distinguished by sundry-figures and letters, corresponding figures and letters
serving to indicate the respective diagrams (Figures 34 to 43) representing such
transverse vertical sections. The greatest or any other principal transverse
vertical section is then designed, as in Figure 36, for example, and the parallel-
ogram I, J, circumscribing the body portion of this section, is divided by any.
convenient number of horizontal and vertical lines set at regular distances apart..
In proceeding to design the after portion of the vessel, each transverse sectional
outline is obtained by constructing a parallelogram, as i, j, (Figures 34, 35, 37,
and 38,) of which the depth and width are respectively equal to the depth and
width marked on the corresponding section line in Figures 32 and 33, by the
lines G, F, and h, h, in the former, and the centre line and the line H, H, in
the latter Figure. The parallelogram i, j,-is next regularly divided by as many
horizontal and as many vertical lines as are employed in dividing the parallel-

page_text: ogram I, J. The sectional outline is then traced on the divided parallelogram,
so as to intersect the divisional lines in precisely the same manner as the out-
line Figure 36 intersects the divisional lines of the parallelogram I,.J. By
these means a flat or convex run is obtained, such run. rising up gradually
along the rearward portion of the vessel, and running up above the water line
at the stern. I adopt this description of run for the purpose of admitting the
water more freely to the propeller; it also admits of the propeller or propellers
being placed further forward than in vessels having the common kind of run.
I also consider my improved form of run to be advantageously applicable in all
cases without reference to the system of propulsion adopted, that is to say, it
is applicable to paddle steamers and sailing vessels as well as to screw steamers.
If the main transverse section of the vessel is a semicircle, the other sections
will be semi-ellipses, according to the geometrical construction herein-before
described, and they may be drawn directly on determining the two axes in
each case, no further geometrical construction being required. The geometrical
process described, however, is applicable to any kind of transverse sectional
outline. The sections of vessels with the ordinary form of run may be designed
or obtained in the same way, it being merely necessary to add to each section
a couple of concave curves, tangential to the vertical centre line and to the
outline previously obtained, in the manner herein-before described. A run of
this kind and obtained in this way is indicated by red lines in Figures 33 to 38
and 41. The degree of concavity of the red curve in each section is in this
instance determined by the red dotted lines K, K, and k, k, in Figures 32
and 33, these two lines representing projections on vertical and horizontal
planes of an imaginary line lying along the hollow of the run, and by means
of them points are determined in each section through which the concave
curves are drawn. A modification of the geometrical process herein-before
described may also be employed in designing the forward part of the vessel.
Parallelograms i, j, Figures 39, 40, 42, and 43, are drawn as for the rearward
sections, and are divided by as many horizontal and as many vertical lines as
in the main transverse section; but instead of being divided equally, the ratios
between the horizontal divisions are gradually and regularly varied towards,
the stern of the vessel, the vertical divisions being equal, as represented in the
Figures just referred to; or the vertical divisions may be varied, the horizontal
ones being equal; or, again, both the horizontal and vertical divisions may be
varied. The degrees of variation in the divisional ratios will depend on the
kind of bow to be given to the vessel, whether it is to have convex or concave
lines, for example, the divisional ratios requiring to be more rapidly varied
in the latter case. In the example given, on Sheet 4 of the Drawings, the

page_text: vertical line of section D is divided by harmonical lines, though any other
convenient mode of dividing the lines may be adopted, and the divisions on
the intermediate sections are obtained by drawing. the curves M, Figure 32,
through the divisions on the section line D, so as to merge into the regular
divisions at any convenient point, as, for example, at the main section: : :①::.
The paralellograms of the several sections being thus divided, points of inter-
section are marked to correspond to the points of intersection on the main
transverse section, and the outline is drawn through the points so obtained.
The geometrical processes herein-before described are obviously applicable
to the designing of all kinds of navigable vessels, and must necessarily give a
series of transverse sectional outlines so related to each other as to produce
a form of vessel of which the lines will blend harmoniously together, as
indicated by the horizontal sections in Figure 33, taken at the several levels
W, L, N, O, P, in Figures 32 and 41, it being unnecessary, as practically
instanced in the design for a vessel, given upon Sheet 4 of the Drawings, to
modify or redraw a single curve as obtained in the manner described after the
main dimensions are once determined on. The top portions of the ship's sides
may of course be designed in any manner to suit the views of the ship builder.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict myself
to the precise details or arrangements which I have had occasion to describe
or refer to, as many variations may be made therefrom without deviating
from the main characteristics of my. Invention; but what I consider to be
novel and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent, is,-
First, the application and use in the propulsion of ships or vessels in water
of screw or oblique-bladed propellers, the radial generatrices of the propelling
surfaces of which form right or acute angles with the axis of the propeller on
the acting side, and the blades of which are shaped with their outer portions
in advance of their central parts, as viewed laterally, for the purpose of placing
the outer and more effective portions of the blades out of the range of the
disturbing or centrifugal action of the central parts, as herein-before described
under the first head of the Invention. -
Second, the combination in a screw or oblique-bladed propeller for marine
purposes of a propelling surface, corresponding to a radial generatrix, inclined.
or curved backwards with an outline, such that the outer portions of the blades
are in advance of the central parts, as viewed laterally, as 'herein-before
described under the first head of the Invention."

page_text: Third, the application and use in the propulsion of ships or vessels in water
of a screw or oblique propelling surface, corresponding to a radial generatrix,
which is inclined more and more backwards as it approaches the axis, the
front and back radial edges of the blades being defined by surfaces, the inter-
sections of which, with planes passing through the axis, make less acute angles
with the axis than any part of the generatrix, as herein-before described under
the first head of the Invention.
Fourth, the system or mode of constructing flexible bladed screw or oblique
propellers with springs between the central parts or bosses of the several pairs
or sets of ribs, and of fitting such ribs upon the propeller shaft with feathers
and grooves, or screw threads, as herein-before described under the second
head of the Invention.
Fifth, the general and 'detailed arrangement and construction, as herein-
before described, of the several modifications of self-acting swivelling-bladed
screw or oblique propellers, comprehended under the third head of the Invention.
Sixth, the system or mode of adjusting the blades of swivelling-bladed screw
or oblique propellers by means of a screw coupling or helical sliding piece,
which may be actuated whilst the propeller is revolving, and a central or an
external tubular shaft, communicating the adjusting motion to the blades by
means of bevil pulleys and chains, cords or belts, or by means of toothed bevil
wheels, as herein-before described under the third head of the invention.
Seventh, the application and use of a connection between the blades of
variable bladed screw or oblique propellers and the throttle expansion or
steam-regulating valve of the driving engines, as herein-before described under
the fourth head of the Invention.
Eighth, the system or mode of constructing screw steamers, in which two
stern keels and two propellers are used with a single rudder at the bow of the
vessel, such rudder being hung in any convenient manner, as herein-before
described under the fifth head of the Invention.
Ninth, the system or mode of designing and shaping navigable vessels or.
ships, as herein-before described under the sixth head of the Invention.
In witness whereof, I, the said Edmund Hunt, have hereunto set my
hand and seal, this Seventeenth day of May, One thousand eight
hundred and fifty-five.
EDMUND HUNT.
(L.S.)