IMPROVEMENTS IN THE CONSTRUCTION OF SCREW PROPELLERS."
Year: 1875

page_text: LETTERS PATENT to Nicholas Demetrius Spartali, of Liverpool, in
the County of Lancaster, Steam Ship Agent, for the Invention of
“IMPROVEMENTS IN THE CONSTRUCTION OF SCREW PROPELLERS."
PROVISIONAL SPECIFICATION left by the said Nicholas Demetrius
Spartali at the Office of the Commissioners of Patents, with his
Petition, on the 10th September 1875.
I, NICHOLAS DEMETRIUS SPARTALI, of Liverpool, in the County of
Lancaster, Steam Ship Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF SCREW PROPELLERS,"
to be as follows :—
The present Invention relates to further improvements on an Inven-
tion for which I obtained Letters Patent dated 24th August 1874,
No. 2900, my object being to obtain high speed by reduced friction of
the blades to the water with greater efficiency and economy of engine
power. I still maintain the principle of diagonal centres as then

page_text: specified, each two blades forming an elongated f, and two such f's
crossing each other diagonally, extending back to the rear of the shaft,
but I now prefer to make my centres larger, the centre of support of the
blades being made ✓ of a long diagonal diamond shape or form, each
consisting of two triangles cut across the thickness and joined or welded
diagonally one to the other. Each blade will thus be placed at a long
-angle_and_cquidistant_from_the other, and also at a considerable
inclination to the back of the centre or boss.
By
I also propose to reduce the width of the blades considerably.
this modification, and by placing the blades in a diagonal diamond shape
centre, or an ordinary round centre, but the blades placed on equivalent
angles to each other and made long and comparatively narrow, and
considerably inclined to the back of the axis or boss, the blades will
follow each other in quick succession, intersecting the water not only
round the boss but diagonally across the back of the centre, intersecting
the water in continuous quick long slices in the depth of the circle,
similar to the action of 4, say, falling in quick succession one after the
other, and presenting their greatest angle in the forward movement, and
receding in their upward travel in the least angle to the water, thus
reducing the friction or resistance of the blades to the water to a
minimum. By this combination, and placing the blades to the centre;
I reduce the angle of inclination or pitch of the blades considerably,
perhaps to say as little as 20 or 25° in relation to the shaft, by which a
great saving of engine power is obtained; and by reducing the width of
the blades still less a pitch of 45 or 50, and 60 degrees of inclination can
be obtained at a much less cost of engine power than a similar pitch
would involve, as the Griffiths' or other well-known propellers now in use.
In fact, with high speed engines working over 100 revolutions per minute
in large steam vessels, and 500 or 1000 revolutions in yachts, such as I
am constructing for the blades of my 4-bladed propeller, are reduced
to dimensions-and-range-similarly-to-a-velocipedo_as_compared to a
common wheel.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Nicholas Demetrius Spartali in the Great Seal
Patent Office on the 10th March 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, NICHOLAS
DEMETRIUS SPARTALI, of Liverpool, in the County of Lancastor, Steam
Ship Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of September, in the
year of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me; the said Nicholas Demetrius Spartali,
Her special licence, that I, the said Nicholas Demetrius Spartali, my
executors, administrators, and assigns, or such others as I, the said
Nicholas Demetrius Spartali, 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 "IMPROVEMENTS IN THE CONSTRUCTION OF SCREW
PROPELLERS," upon the condition (amongst others) that I, the said
Nicholas Demetrius Spartali, my executors or administrators, by an
instrument in writing undor 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 Nicholas Demetrius Spartali, 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, reference being had to the Drawings
hereunto annexed, and to the letters and figures marked thereon (that
is to say):-
The present Invention relates to further improvements on an Inveṇ-
tion for which I obtained Letters Patent dated 24th August 1874,
No. 2900, my object being to obtain high speed with reduced friction of

page_text: the blades on the water, and greater propelling efficiency and economy
of engine power. I still maintain the principle of diagonal centres set
forth in the Specification of the said Patent, each two blades forming
_an elongated f, and two such f's crossing each other diagonally,
extending back to the rear of the shaft, but I now propose-to-make-my-
centres larger, the centre of support of the blades being made of a long
diagonal diamond shape or form, each consisting of two triangles cut
across the thickness and joined, welded, or forged diagonally one to the
other. Each blade will thus be placed at a long angle and equidistant
from the other, and also at a considerable inclination to the back of the
· centre or boss.
and
I also propose to reduce the width of the blades considerably,
also to lengthen them. By this modification, and by placing the blades
on a diagonal diamond shape centre, or an ordinary round centre, but
the blades placed at equivalent angles to each other, and made long and
comparatively narrowed and considerably inclined to the back of the
axis or boss, the blades will follow each other in quick succession, and
will intersect the water not only round the boss, but diagonally across
to the back of the centre, thereby cutting the water in continuous
quick long slices in the depth of the circle, similar to the action of
four oars falling in quick succession one after the other, and presenting
their greatest angle in the forward movement, and receding in their
upward travel as the least angle to the water, thus reducing to a
minimum the friction or resistance of the blades to the water. By this
combination and mode of adapting the blades to the centre I reduce the
angle of inclination or pitch of the blades considerably, perhaps to say
as little as 20 to 25 in relation to the shaft, by which means a great
saving of engine-power-is-obtained,-and-by-reducing-the-width_of_the_
blades still more a pitch of 45, or 50, or 60 degrees of inclination can
be obtained at a much less cost of engine power than a similar pitch
would involve in the Griffiths' or other well-known propellers now in
use. In fact, with high speed engines working over 100 revolutions per
minute in large steam vessels, and 500 and 1000 revolutions in yachts
(such as I am constructing), the blades of my four bladed propeller are
constructed of greater length and lesser width than heretofore, but with
a greater pitch, or in other words, at a greater angle of inclination to the
shaft, so that from one-third to one-half of the length of the propeller
shall be to the rear of the boss.
-

page_text: Diades.
Figure 14 is a perspective view of a three-bladed. propeller having
-arched blades; the end of each blade should-reachi_a_distance_of_about.
half its length to the rear of the boss; the blades of this propeller may
however be straight, but should in all cases be at the same angle of
inclination to the boss.
Figure 15 is a perspective view of a three-bladed single action
propeller with branch blades with curve rearwards to the back of
centre.
Figure 16 is a front view of a two-bladed propeller with branch blades
added to main blades, and Figure 17 is a front view of three-bladed
propeller with branch blades added to the main blades.
Figure 18 is a four-bladed propeller with branch blades added to the
main blades, all acting on the same principle of curves from the rear
to the front. These branch blades perform useful and effective. work,
and materially increase the power of the propeller. By these branch
blades additional propelling power or surface is obtained on the same
'rotation of the propeller to the engine (nearly half as much more) with
a very small addition of metal, and at a point causing the least resistance
to the water, and without additional centres or masses of metal churning
or rotating round, carrying and lifting water instead of doing useful
propelling work. Such additional branch blades added to my two,
three, or four bladed propellers on the principles described would offer
a minimum resistance to the water, and could be worked with the
same engine power. These branch blades can be screwed carefully
_and_fitted with great_nicety,-and-smoothed-and-planed-on-to-the-main
blades so as to present even and smooth surface to the water, and at the
same time made strong to resist all possible strain.
The branch blades may act to front or to rear of shaft, both or one
set on same propeller; also transverse light diagonal narrow-bladed
strips of metal may be used as struts between each two blades for
strengthening the branches, and to enable them better to resist the
pressure of the water.
.
In constructing my propellers I take two long narrow blades of a
given thickness of iron, steel, or other metal, wider at their base. I file,.

page_text: turn, grind, or otherwise make their surfaces even and smooth, and
weld, forge, or otherwise join them the one to the other diagonally
across their widest diameter at their base, that is to say, the base of
the blade being cut diagonally the one is crossed diagonally on the edge
and extreme corner end of the others. This mode of assembling together
the blades previous to welding or otherwise joining them is clearly
shewn in Figures 19 and 20, Sheet III., and Figures 21, 22, and 23,
Sheet II., shew such a four-bladed propeller having each of the two
blades thus put together forming an elongated diagonal letter f, the
back where the two angles join diagonally forming the centre for the
shaft, and two such diagonal f's crossing each other diagonally across
the shaft form my four-bladed propeller; these may be welded, dove-
tailed, joined, or forged together, according as they are constructed,
either in wrought or mallcable iron or steel or other metal to a common
centre, or they may be cast in onc, the blades and boss being at similar
and equivalent angles and inclination of the blades diagonally to and
across the centre or axis, the spaces between the roots of the blades
forming hollows or grooves or clear waterways to the side and back,
by which arrangement each blade as it rises from the lower to the upper
surface in its rotation round the axis is performing useful propelling
work from its very base or root to the extreme point, and each blade
following in the wake of its predecessor in quick succession, and per-
forming the like useful propelling work, and by the nature of the
fundamental diagonal connection of cach, blade to the other, and to
the consequent respective inclination to the centre, and by reclining
each blade to the rear of the axis at a gradual slope forming from
¼ to ½ its length from the extreme front of the boss and fore part of
the blade, I obtain a most effectual propelling effect, each blade cutting
and displacing the water in a large mass in a long curvilinear slice
O from the rear or solid content of the circle of rotation to the right, and
from thence to the left front of the axis, each blade rising thence to the
upper half of the circle presenting the least frictional surface and
resistance to the water to repeat the same action from left to right,
and from the rear of centre to the front of centre shaft, so that all
5 churning of, or carrying water round, or lifting water, as is the case
with most of the present propellers in use, more or less, and the centre
water and back water forming a dead mass behind the ship's stern
with present propellers is wholly and most beneficially utilized and
"
acted upon.

page_text: Figure 7 shewing the TOUT-DIAUcu propor
over my blades gradually tapering to-a-round diminished-end or point,
and place them straight in the said angles to the centre; or curve and
arch-them more or less.
In the case of my two-bladed propellers in order to obtain a larger
scope each blade is made to project outwards to the front of centre to
considerable angle, the two blades forming two distinct arms.
Some I construct with wider, some narrower, some longer, some
shorter, all in elongated, more or less arched or semi-arched blades, and
more or less scooped or caved out; they thus displace a very large mass
of water, some in a curvilinear line from left to right, and some, those
with concave blades, displacing more still diagonally, and from the back
to the front of shaft, as shewn in the various forms of my improved pro-
pellers illustrated on Sheets III. and IV., of the accompanying Drawings.
From the above description it will be understood that the water which
surrounds the centre of the propeller at the boss is acted upon beneficially
instead of being left as usual as a dead mass by the present propellers,
and particularly in large steam vessels. It will be seen that by the
action of the blades to the rear of centre a beneficial effect will be
produced on the back water, caused by the suction of the ship's stern
portion on her progress forward. This dead water and the part not
operated upon by the present propeller or centre water causes a mass of
dead water to clog behind, and diminishes very materially the effect of
the propellers, which at present principally throw the water from-one
side to the other, and by the size of the blades and-nature of the large
boss and sharp inclination meet the water in full surface on their
upward travel,-thus causing a great amount of friction, which becomes
"very serious and the cause of an immense waste of engine power in high
speed engines. My improved blades being long and narrow, and the
angle of inclination very gradually increasing, and with the centres
small but very strong (by the nature of its construction), and by the
roots of the blades being placed angle and angle, and diagonally across
with a considerable incline to the back will produce a very beneficial
effect. In fact the centres of my high speed propeller will be forged

page_text: in refined metal composed of iron or steel, and with two triangles
welded to each other across their thickness, and serving as a foundation
for the roots of the blades; or the blades themselves may be welded to
each other diagonally to their ends, which I make of thicker metal com-
pared to the blades.
It will be seen that the propellers are made with two, three, four, or
more blades, the one blade set diagonally to the other in their extreme
angles, the one falling in the immediate wake and covering the space
left by the former one.
My shafts are either made to go right through my boss of the
propellers, or the front of them being slight in some cases, owing to the
great diagonal curves of the blades, and where the greatest thickness
of metal is, to the rear of the blades. (as is generally the case with these
propellers) I rivet or otherwise secure the shaft into a long substantial
tube forming part of the centre or boss of the propeller itself.
Having now described my Invention of "Improvements in the Con-
struction of Screw Propellers," and having explained the manner of
carrying the same into effect, I claim as the Invention secured to me by
Letters Patent as aforesaid,-
Constructing screw propellers with elongated narrow blades set
diagonally to each other and at an angle on a strengthened boss, as
hercin set forth, the blades being so arranged that their outer ends
extend considerably beyond the end of the boss, so as to act more
beneficially as propelling agents on the dead water, and at the same
time economize or more advantageously utilize the power of the driving
engine.
I claim this arrangement or construction of parts, whether adapted
to a two, three, or more bladed propeller, and whether the blades be
straight or curved, and simple or branched, as shewn in the Drawings.
In witness whereof, I, the said Nicholas Demetrius Spartali, have
hereunto set my hand and seal, the Eighth day of March, in
the year of our Lord One thousand eight hundred and seventy-