IM- PROVED MEANS OR APPARATUS FOR PROPELLING VESSELS
Year: 1873

page_text: LETTERS PATENT to Henry Hurley Stevenson, of
Sunbury-on-Thames,
in the County of Middlesex, Gentleman, for the Invention of "IM-
PROVED MEANS OR APPARATUS FOR PROPELLING VESSELS."
Sealed the 24th October 1878, and dated the 2nd May 1873.
PROVISIONAL SPECIFICATION left by the said Henry Hurley Stevenson
at the Office of the Commissioners of Patents, with his Petition,
on the 2nd May 1873.
I, HENRY HURLEY STEVENSON, of Sunbury-on-Thames, in the County
3 of Middlesex, Gentleman, do hereby declare the nature of the said In-
vention for "IMPROVED MEANS OR APPARATUS FOR PROPELLING VESSELS," to be
as follows:-
This Invention which relates to improved means or apparatus for "pro-
pelling vessels consists mainly in accomplishing this object by means of
tubes or syphon tubes, or arched recesses, or boxes projecting inwards
from the vessel's bottom or sides in combination with screws placed and
working therein.

page_text: The Invention is designed to increase the speed of vessels propelled
by screws, by increasing the area of the latter without increasing their
diameter, and by increasing their diameter without increasing the
vessel's draught of water. This I effect by enclosing the screws in the
said tubes or recesses (as above referred to) which increases their power,
prevents slip, and greatly reduces the vibratory motion attending screw
propellers as hitherto constructed and applied, besides obviating the
liability to injury to which external screws are subjected.
The Invention can be applied equally well to vessels propelled either
by steam, manual, or other power.
1
The tubes, recesses, or boxes, may be situated in any part of the
vessel's sides or bottom. When placed in the latter position I construct
them of a syphon form, and fit valves or stop-cocks to the upper part or
bend of the syphon, through which when open, the air in the tubes
escapes by the pressure of the water rising therein. These valves are 1
sufficient for this purpose when the diameter of the screw is less than
the vessel's draught of water, but when it is greater then in addition
to the valves I apply air pumps or exhausters (which may be connected
with and worked by the engine if necessary) in such a way that when
the former are open the water rises in the tubes to the level of the water 2
outside the vessel, but when closed by working the air pumps, the whole
of the air in the tubes can be exhausted, when the water by atmo-
spheric pressure will rise to the top of and completely fill the tubes,
and enable the screws to rotate in a solid body of water.
Instead of forming the screws with two or more blades as now 2
practised, I form them with one continuous blade of one complete turn..
(or nearly so) round the central boss or axis, forming thereby "disc"
screws, the pitch of which may be varied to suit the power of the
engine or other force used to work them, or other requirements.
SPECIFICATION in pursuance of the conditions of the Letters Patent, 80
filed by the said Henry Hurley Stevenson in the Great Seal Patent
Office on the 1st November 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
HURLEY STEVENSON, of Sunbury-on-Thames, in the County of Middlesex,
Gentleman, send greeting.
35

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Second day of May, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Henry Hurley Stevenson, Her special
licence that I, the said Henry Hurley Stevenson, my executors, adminis-
trators, and assigns, or such others as I, the said Henry Hurley Stevenson,
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
“IMPROVED MEANS OF APPARATUS FOR PROPELLING VESSELS,” upon the con-
dition (amongst others) that I, the said Henry Hurley Stevenson,
my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what.
manner the same was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Hurley Stevenson, do hereby
declare the nature of my said Invention, and in what manner the samo
is to be performed, to be particularly described and ascertained in and
by the following statement in writing, and on reference being had to the
accompanying Drawing, that is to say:
-
This Invention which relates to improved means or apparatus for pro-
pelling vessels consists mainly in accomplishing this object by the appli-
cation to the vessels of syphon tubes, or of any other equivalent means,
such as arched recesses or boxes projecting inwards from the vessel's
bottom or sides in combination with propelling screws placed and working
therein.
The Invention is illustrated on the accompanying Drawing in Figure 1
which shows its application to the hull of a vessel, represented by the
letter a.
The Invention is specially designed to increase the speed of vessels
propelled by screws, as it allows of the area of the latter being increased
without any increase of diameter, and also of the application to a vessel

page_text: of a given size of a screw of much greater diameter than any other
system will allow.
6 represents the syphon tube (or its equivalent as above referred to)
which may be situated in the vessel sides, but by preference it is placed
in its bottom, amidships, or towards its head. To the bend or upper-
part of the syphon I apply a valve or stop-cock c through which, the air
which from time to time accumulates in the bend of the tube is allowed
to escape so that the water shall fill the tube. The valve c is sufficient
for this purpose when the diameter of the screw is less than the vessel's
draught of water, but when it is greater I apply in connection with the
valve c a suitable air pump or exhauster which may be connected with
and worked by the engine if desired, so that when the valve is opened
the water will rise in the tube to the level of the water outside the
vessel, but when closed by working the air pump, the air remaining in
the tube above the water level can be exhausted, when the water by the
exterior atmospheric pressure will rise to the top of and completely
fill the tube, and enable the screw to rotate in a solid body of water,
partly above the level of the water surrounding the vessel, which it will
readily be seen is one of the main advantages derived from the appli-
cation of the syphon tube, inasmuch as it allows of vessels navigating
narrow rivers and canals without injury to their banks, there being no.
wash or disturbance of the surface of the water from the action of the.
screw, and also of the application to a vessel of a given draught of
screws of much greater diameter with proportionate engine power, than
any other system can render attainable. The advantage thus obtained is
further utilized by the application within the tubes 6 of "disc
screws d, having a blade of one complete turn or nearly so) round a
central boss or axis e which it will be observed gives a greater acting area
on the water in the tube than an ordinary screw without any increase of
diameter. The power of the screw is thus greatly increased, slip is pre-
vented, and the vibratory motion attending screw propellers as hitherto
constructed and applied is greatly reduced and the liability to injury
and derangement to which external or unprotected screws are subjected
is obviated. The screw is mounted upon an inclined shaft ƒ which is
retained in position by a footstep 7 and a bearing or journal h. The
pitch of the screws d can be varied to suit the power of the engine or
other power used to work them, or other requirements, but any ordinary
or other kind of screw can be used in combination with the tubes 6, and
"

page_text: the Invention can be equally well applied to vessels propelled either by
steam, manual, or other power.
The mounting and arranging of the screw will of course have to be
modified or varied in proportion to the size of the vessel it is to be
fitted to.
Any required number of the tubes and screws can be applied to any
one vessel.
Having now described the nature and object of my said Invention for
"Improved Means or Apparatus for Propelling Vessels," together with
the manner in which the same is to be or may be performed or carried
into practical effect, I would remark in conclusion that I claim as my
Invention the application to a ship, boat, or vessel, of a syphon tube
or tubes, admitting of the application to a vessel of a given size and
draught of water of a propelling screw of much greater diameter and
length of pitch with proportionate engine power than any present
system admits, in combination with an interior propelling screw or
screws, by preference of a disc form, substantially as above described
and as illustrated on the accompanying Drawing, or any equivalent
modification thereof.
In witness whereof, I, the said Henry Hurley Stevenson, have here-
unto set my hand and seal, this Thirtieth day of October, in
the year of our Lord One thousand eight hundred and seventy-