IMPROVEMENTS IN OR CONNECTED WITH SCREW PROPELLERS
Year: 1867

page_text: LETTERS PATENT to William Henry Whettem, of Portsmouth, in the
County of Hants, and Edmund Walker, of Poplar, in the County of
Middlesex, for the Invention of "IMPROVEMENTS IN OR CONNECTED WITH
SCREW PROPELLERS."
PROVISIONAL SPECIFICATION left by the said William Henry Whettem
and Edmund Walker at the Office of the Commissioners of Patents,
with their Petition, on the 27th May 1867.
We, WILLIAM HENRY WHETTEM, of Portsmouth, in the County of Hants,
and EDMUND WALKER, of Poplar, in the County of Middlesex, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN OR CONNECTED
WITH SCREW PROPELLERS," to be as follows:-
Our Invention consists in enclosing screw propellers in a barrel or tubular
casing open at both ends.
We either cause this barrel or casing to revolve with the propeller, or we
make it a fixture. In the latter case the upper side of the barrel is secured
to the ship's bottom by angle irons or otherwise, and the under side is secured

page_text: in a similar manner to the keel, while for additional security stays extend
from the sides of the barrel to the "run" of the vessel. This barrel or casing
compels the water acted on by the screw to be forced in a line with the
propeller shaft, whereby we obtain greater power than from an unenclosed
screw; the barrel or casing also protects the screw from fouling, it diminishes
or prevents the vibration, and when a fixture adds to the strength of the
vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Henry Whettem and Edmund Walker in the
Great Seal Patent Office on the 27th November 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, WILLIAM
HENRY WHETTEM, of Portsmouth, in the County of Hants, and EDMUND
WALKER, of Poplar, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of May, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said William Henry Whettem and Edmund Walker, Her special licence
that we, the said William Henry Whettem and Edmund Walker, our executors,
administrators, and assigns, or such others as we, the said William Henry
Whettem and Edmund Walker, our 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 OR CONNECTED WITH SCREW PROPELLERS," upon the condition
(amongst others) that we, the said William Henry Whettem and Edmund
Walker, or one of us, our executors or administrators, by an instrument in
writing under our, or one of our, 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 we, the said William Henry Whettem and Edmund
Walker, do hereby declare the nature of our said Invention, and in what
manner the same is to be performed, to be particularly described and

page_text: ascertained in and by the following statement thereof, reference being had to
the Drawings hereunto annexed, that is to say:-
Our Invention consists in enclosing screw propellers in a barrel or tubular
casing open at both ends in the manner and for the purposes herein-after
explained.
The upper side of the tubular casing is secured to the ship's bottom by angle
irons or otherwise, and the under side is secured in a similar manner to the
keel, while for additional security stays extend from the sides of the tubular
casing to the run of the vessel. It is important that the inside diameter
of the tubular casing should be equal to the diameter of the screw in inches
multiplied by 014", and it is also important that the length of the tubular
casing fore and aft and the length of the screw should be to each other as
3 to 2, that is to say, that the length of the tubular casing should be equal to
once and a half the length of the screw; it is likewise important that the
tubular casing should be nearly even or flush with the screw at the fore
side.
Our Invention will be fully understood by the accompanying Drawings.
A is the screw propeller, and B is the tubular casing in which it is enclosed;
this casing is open at both ends, and it will be observed that at the fore side
the tubular casing and the screw are nearly even or flush, and that the length
of the tubular casing is about once and half the length of the screw; C, C, are
angle irons securing the upper side of the tubular casing to the ship's bottom,
and D, D, are other angle irons securing its under side to the keel; E, E, are
stays extending from the sides of the tubular casing to the "run" of the
vessel, and F, F, are other stays extending from the casing to the rudder
post.
The following advantages are gained by our Invention:-The resistance
offered by the tubular casing in the passing of the screw blades through dense
water effectually stops the vibration which is so apparent when the screw is
unprotected; as the water is more equally distributed on each side of
the rudder as it passes from the screw, the rudder is kept steadier and the
ship can consequently be steered more easily; as the pressure aft occasioned
by the revolutions of the screw propels the ship, and as the tubular casing
prevents the water being thrown in any other direction, the casing therefore
tends to increase the speed of the ship; as vibration is avoided, as before
explained, the engines work more regularly and smoothly; the keel in the
wake of the ordinary screw aperture is wholly unsupported, but by the con-
nections consequent upon the fitting of the tubular casing it becomes attached
to the body of the ship, and thereby, as well as the stays, materially strengthens

page_text: the vessel; the tubular casing also protects the screw from being fouled by
warps or otherwise.
In witness whereof, I, the said William Henry Whettem, for myself and
on behalf of the said Edmund Walker, have hereunto set my hand
and seal, this Twenty-seventh day of November, One thousand eight
hundred and sixty-seven.
W. H. WHETTEM. (L.S.)