AN IMPROVED CONSTRUCTION OF SCREW PROPELLER
Year: 1860

page_text: LETTERS PATENT to Julian John Révy, of York Street, Portman Square,.
in the County of Middlesex, Civil Engineer, for the Invention of "AN
IMPROVED CONSTRUCTION OF SCREW PROPELLER."
Sealed the 19th February 1861, and dated the 24th August 1860.
PROVISIONAL SPECIFICATION left by the said Julian John Révy at the
Office of the Commissioners of Patents, with his Petition, on the 24th
August 1860.
I, JULIAN JOHN REVY, of York Street, Portman Square, in the County of
Middlesex, Civil Engineer, do hereby declare the nature of the said Invention
for "AN IMPROVED CONSTRUCTION OF SCREW PROPELLER," to be as follows:
The object of this Invention is to construct an efficient screw propeller,
of such kind that it shall obviate the loss of power arising from the "slip" of
an ordinary screw, and from the shock of its concussion with the water. The
loss in effective power attendant upon all ordinary propellers arises from the
principle of their action and proceeds solely from the conditional relative
velocity of the screw surface which operates upon the water surrounding
the screw. My propeller is so constructed that its acting screw surfaces have
no relative velocity to the water which surrounds them; in order, however, that
the water may be submitted to their action the screw surfaces are so peculiarly
constructed that cells are formed through which the water is forced to flow.

page_text: Islands, and Isle of Man, an Invention for "AN IMPROVED CONSTRUCTION OF
SCREW PROPELLER," upon the condition, amongst others, that I, the said Julian
John Révy, 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 Julian John Révy, do hereby declare
the nature of the 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, reference being had to the Drawing hereunto aunexed, and to
the letters and figures marked thereon (that is to say):-
The object of this Invention is to construct an efficient screw propeller, of
such kind that it shall obviate the loss of power arising from the "slip" of
an ordinary screw and from the shock of its concussion with the water. The
loss in effective power attendant upon all ordinary propellers arises from the
principle of their action and proceeds solely from the conditional relative velocity
of the screw surface, which operates upon the water surrounding the screw. My
propeller is. so constructed that its, acting screw surfaces have no relative
velocity to the water which surrounds them; in order, however, that the water
may be submitted to their action, the screw surfaces are so peculiarly
constructed, that cells are formed through which the water is forced to flow.
These cells have progressively diminishing cross sections, and by these a
velocity is gradually imparted to the whole mass of water flowing through
them. The reaction caused in the inert mass of water by the velocity so im-
parted is the motive power for the propulsion of the ship. In order to form
the cells; I gradually increase the measurement of the cross section of the
blades, until the maximum measurement is obtained at about the middle of
the length of the blades, by curving the front face or acting surface of each
blade outwards from the front edge. The blades so formed are surrounded by
a cylindrical case. The angle of inclination for the initial pitch of the screw,
at its periphery to a perpendicular plane of the axis of the screw is to be taken
at less than 30°, in order that the screw may work most advantageously. A
screw constructed according to these data works with equal advantage at all
velocities and also against adventitious resistances with an expenditure of
force exactly proportionate to the resistance for the time being.
In the accompanying Drawing I have illustrated my Invention, as applied to
the construction of a progressive screw, nine feet in diameter; Fig. 1 is a side
view of the "progressive screw," which is fitted with six blades forming as

page_text: These cells have progressively diminishing cross sections, and by these a
velocity is gradually imparted to the whole mass of water flowing through
them, the reaction caused in the inert mass of water by the velocity so imparted
is the motive power for the propulsion of the ship. In order to form the cells.
I gradually increase the measurement of the cross sections of the blades until
the maximum measurement. is obtained at about the middle of the length of
the blades by curving the front face or acting surface of each blade.outwards
from the front edge.. The blades so formed are surrounded by a cylindrical
It will now be understood that each cell has two openings. of different
sizes, one for the entrance, the other for the departure of the water.
The angle of inclination for the initial pitch of the screw, at its periphery,
to a perpendicular plane of the axis of the screw is to be taken at less than
30°, in order that the screw may work most advantageously. A screw con-
structed according to these data works with equal advantage at all velocities.
and also against adventitious resistances, with an expenditure of force exactly
proportionate to the resistance for the time being..
The diameter of the progressive screw will be considerably less than that
of a corresponding ordinary screw and may even be brought to one half. The
progressive screw acts at the stern of the vessel and is entirely submerged. In
all ordinary cases it may be cast in one piece.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Julian John Révy, in the Great Seal Patent Office on the
23rd February 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JULIAN
JOHN REVY, of York Street, Portman Square, in the County of Middlesex,
Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of August, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Julian John Révy, Her special license that I, the said Julian John Révy, my
executors, administrators, and assigns, or such others as I, the said Julian
John Révy, 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

page_text: many cells for the passage of the water through the screw. .Fig. 2; is á
.section of the screw taken through the centre of the boss and the cylindrical
case. The length of the progressive screw. taken in the direction of its axis
depends upon the form of the blades and is in the present instance 3 feet:
Fig. 8 represents two blades of the progressive screw as they would appear
at the periphery of the screw, if stretched out on a plane surface, that is
with an increasing thickness of cross section from A to C; (Fig. 3) and a
diminution from this point to B, whereby (the back face of the blade being
an ordinary screw surface set at an angle of about 26°) the cell of the screw
at the periphery is contracted gradually to the point C. The blades revolvė
round the axis in the direction shown by the arrow, and as they also have the
velocity of the ship in the 'direction of the axis of the screw, there arises
from these two motions a resulting motion from A to A which falls in the
elongation of A, B. By this arrangement, the water which enters at a cross
section of 2-118 feet is forced to pass out at a cross section of 1-8101 feet 3
and since the same mass of water that passes out-of the last cross section.
must enter through the first, it is clear that this quantity of water must pass
out of the narrower cross section with a greater velocity than that with which
it entered the wider one. This difference of velocity is gradually imparted
to the whole mass of water and the reaction arising therefrom is the motive
power for the propulsion of the ship.
The boundary lines of a blade of the progressive screw shown in Fig: 3; if
drawn to the full size, will be the templets according to which the boundary
surfaces are formed and determined in execution; or, as they are also called,
their directrices.
My improved screw I apply to the stern of the vessel and entirely submergé
it. In general I prefer to cast it in one piece. The present Drawing of a
progressive screw is designed for a ship which, at a speed of twelve miles an
hour, has to overcome a resistance of 8,640 pounds: At this speed of the ship
the progressive screw has to make 75-06 revolutions per minute, and the total
force of the motion for this screw under these circumstances would be 827-34
horse power. The velocity which is gradually imparted to the mass of water by
the blades of the progressive screw is in this case 11-733 feet per second in the
contrary direction to the motion of the ship. The advantages derivable from
the use of this Invention are a considerable saving of motive power and a
material rednction in the diameter of the screw as compared with screws of
any of the well known constructions having equal propulsive efficiency.
.
Having now set forth the nature of my Invention of "An Improved Construc
tion of Screw Propeller," and explained the manner of carrying the same into

page_text: effect, I wish it to be understood that under the above in part recited Letters
Patent I claim the peculiar construction of progressive screw above described
for the propulsion of vessels.
In witness whereof, I, the said Julian John Révy, have hereunto set
my hand and seal, this Twenty-second day of February, in the year of
our Lord One thousand eight hundred and sixty-one.
Witness,
J. W. MOFFAT.
66, Chancery Lane.
JULIAN JOHN REVY. (L.S.)