IMPROVEMENTS IN PROPELLING
Year: 1853

page_text: LETTERS PATENT to Maxwell Scott, of Birkenhead, in the County
of Chester, Engineer, for the Invention of "IMPROVEMENTS IN
PROPELLING."
PROVISIONAL SPECIFICATION left by the said Maxweil Scott at
the Office of the Commissioners of Patents, with his Petition,
on the 1st June 1858.
T, MAXWELL SCOTT, of Birkenhead, in the County of Chester, Engi-
neer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN PROPELLING" to be as follows:-
I propose to use two blades, which are to be on their surface of the
form of the thread of a screw, the pitch varied as circumstances may
require, and having two arms for attaching such blades to the boss or
centre, which arms are to be of a form suitable to the pitch. The
position of the blades is to be such that the centre of the blades' length
may be fixed opposite to the centre of the boss, and the arm may be
one fourth of the length of the blades, and fixed at one end.
The propeller will be of the form represented in the Drawing an-
nexed, differing from other screws in its having the driving surface

page_text: chiefly at the circumference, and being comparatively open between
the blades and the boss, thus allowing the water a passage, preventing
churning and other evil effects attendant upon the working of the
screws in present use, and enabling vessels to be effectually steered,
whether the screw be in motion or stationary, as in both cases the
water is not impeded.
I also propose in certain cases to make the blades in separate pieces
from the arms, so as to give liberty of motion for the purpose of
feathering when the screw is stationary, and thus diminish the im-
pediments to the vessel's sailing, and also for the purpose of altering
the pitch when requisite.
It must be understood that I do not confine myself to the use of
two blades, nor to any particular dimension or proportion; but what I
wish to claim in this Invention is, the arrangement and adaptation of
the several parts, as described, with the view of getting the driving
surface mainly from the outer edge, and as much space as possible
between the blades and boss, to allow the water free passage; and I
also wish to claim the application of these improvements to any of the
present screws in use.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Maxwell Scott in the Great Seal Patent Office,
on the 1st December 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, 1,
MAXWELL SCOTT, of Birkenhead, in the County of Chester, Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the First day of June, in the year of
our Lord One thousand eight hundred and fifty-three, in the sixteenth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Maxwell Scott, Her special licence. that I,
the said Maxwell Scott, my executors, administrators, and assigns, or
such others as I, the said Maxwell Scott, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to

page_text: 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 "IMPROVEMENTS IN PROPELLING,"
upon the condition (amongst others) that I, the said Maxwell Scott,
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 Maxwell Scott, do hereby declare
the nature of my 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, reference being had to the Drawings
hereunto annexed, that is to say:
My Invention consists, first, in a new form or construction of screw
propeller for ships and vessels, whether sca-going or employed in inland
navigation, the peculiar features of which consist in its having the
driving surface chiefly at the circumference of the blades, or at that
part of the blades furthest from the boss, and in the blades being
affixed to their arms in such manner as to leave as much vacant or un-
occupied space as possible between the blades and the boss.
Second, in a mode or modes of attaching or connecting the blades or
screw propellers to the arms by which they are carried; and,
Third, in an arrangement or combination of parts for the purpose of
enabling the blades of screw propellers to be feathered or brought to
different positions in relation to the arms by which they are carried.
Figures 1, and 2, of the Drawings annexed are respectively a side
and plan view of a two-bladed propeller constructed according to the
first part of my Invention. Figure 3, is a plan view of a single blade
detached, placed, however, at a different angle with respect to its arm
from that shewn as being given to the blades in Figures 1, and 2; and
Figure 4, is a plan or front view of a three-bladed propeller constructed
according to my Invention. In these Figures the same letters of refe-
rence are used to denote similar parts, and the same general descrip-

page_text: tion will therefore serve in each particular case. D, D, are the blades
of the propellers, which are to be of the form of a portion of a screw, the
pitch of which may be varied to suit the circumstances of the par-
ticular use for which the propellers are intended. D*, are the arms
by which the blades are attached to the boss E: these arms may
be cast in the same piece with the blades and boss, or formed in de-
tached parts, as hercin-after described. The length of the blades D, 1
propose to make equal to three fourths the diameter of the propeller,
and the width one sixth of such diameter, but I do not confine myself
to these proportions. I also prefer the position of the blades to be such
as that the centre of the blade may be in a line with the centre of the
boss, as seen in Figure 2. The width of the arms D*, I prefer to be
about one fourth of the length of the blades D, and the length of the
arms proportioned to the diameter of the propeller. It will be seen that
by adopting these arrangements each blade will have a vacant space Z,
between its acting surface and the boss E, as shewn by the letters A, B, C,
Figures 1, 3, and 4, thereby forming the propelling surface chiefly at the
outer edge of the blades, and by the absence of obstruction at the part Z,
giving a free passage to the water, thus preventing churning and other
ill effects to which screws of the ordinary description are subject.
The facility for steering is also increased when the screw is in motion
or at rest, as in both cases the passage of the water to the rudder is
I do not
not impeded to such an extent as with ordinary screws.
confine myself to the use of any particular number of blades, nor to the
exact details above given, so long as the peculiar form of screw blade
described is employed.
Figures 5, 6, 7, and 8, exhibit a side view, a vertical section, a cross
section, and an edge view of a two-bladed propeller constructed with
moveable blades, according to my second improvement. F, F, are the
arms on which the blades are mounted. These arms are made of
wrought iron or other suitable material, having a boss Fx, by which
they are affixed to the propeller shaft, and together may be of a length
equal to the diameter of the screw, each arm being of the length
of half the diameter, or less if required. II, II, are the blades, which
may be composed of wrought iron or other suitable material, and either

page_text: of the shape shewn, or of the shape of ordinary screw blades, having
each a socket or hole, either cast therein or bored out, and extending
throughout the length of the blade, or through a portion only of its
length, to receive the arms, which are turned for that purpose. By
this means the blades will be moveable round their respective arms, and
after having been set to the pitch most suitable for the vessel they can
be securely fixed to the arms in that position by means of keys or
cotters and nuts G, (Figures 6, and 7.) or by any other convenient
means.
Figures 9, 10, 11, 12, and 13, are representations of the arrange-
ment, which constitutes the third part of my Invention, for the purpose
of feathering or altering the pitch of the blades of screw propellers.
IT, H, are the blades of the propeller, which are made moveable on
the arms F, F, as before described, and have cach a crank L, slotted,
as shown in Figure 12, fixed to the bottom of the blades. On the out-
side of the boss x, is another boss 1, Figures 10, 12, and 13, which
moves freely over the boss FX, having a part cut away at the centre to
enable it to pass the arnis F, F, and a stud or pin M, fixed in it to
work in the slot of the crank L. On the end of the boss I, is turned
a groove i, Figures 10, and 13, in which groove is fitted the ring K,
which is formed in two parts, and is capable of turning freely in the
groove i N, N, are two rods, which are attached to the ring K, and
pass inwards through the stern of the vessel, working in stuffing boxes
Y, Y, to prevent the influx of the water. These rods may be made
of any required length, according to convenience. U, is a ring, to
which the inner ends of the rods N, are attached. To this ring U,
are jointed two links O, the opposite ends of which are connected to
the bell crank levers P, P, which are fixed on the shaft Q, which shaft
may be supported in bearings attached to the side of the vessel, or other-
wise conveniently mounted. The opposite extremities of the bell crank
levers are connected together by a cross shaft, to the centre part of
which is fixed the screw R, on which works the hand wheel S, which
is tapped through the centre with a female screw to suit the thread of
the screw R. The whee! S, has its bearings in a bracket T, which
may be fixed in the cabin or on deck, or in any other convenient

page_text: situation. By turning the wheel S, in either direction, it will raise or
depress the screw R, which, through the intervention of the bell-cranked,
levers P, P, and the links O, O, will cause the rods N, N, to give
motion to the ring K, and boss I, and by means of the studs M, M, on
the boss I, the cranks L, L, will be turned, and the blades H, H, of
the propeller thereby moved on their arms, so as to alter the pitch of
the screw or feather it when necessary.
And having now described the nature of my said Invention, and in
what manner the same is to be performed, I declare that I claim as
my Invention,―
First, the construction of screw propellers with blades of the
peculiar form represented in Figures 1, 2, 3, and 4, of the Drawings
annexed and herein-before described; that is to say, with the driving
surface chiefly at the outer edge of the blades, and as large a vacant
space as may be left between the driving surface and the boss.
Second, the mode of affixing the blades of screw propellers by means
of arms on which they are carried, as represented in Figures 5, 6, 7,
and 8, of the Drawings annexed and hercin-before described, whether
such arms are used with the peculiar form of blade before described
or any other form of blade, and whether such arms pass through or
partly through their respective blades. And,
Third, the arrangement for feathering or altering the pitch of the
blades of screw propellers, represented in Figures 9, 10, 11, 12, and 13,
of the Drawings annexed and herein-before described.
In witness whereof, I, the said Maxwell Scott, have hereunto set
my hand and seal, this Seventeenth day of November, One
thousand eight hundred and fifty-three.
MAXWELL SCOTT. (L.S.)