IMPROVEMENTS IN SCREW PRO- PELLERS.
Year: 1872

page_text: LETTERS PATENT to Michael Burke, of Liverpool, in the County of
Lancaster, for the Invention of "IMPROVEMENTS IN SCREW PRO-
PELLERS.
"
Sealed the 20th December 1872, and dated the 24th June 1872.
PROVISIONAL SPECIFICATION left by the said Michael Burke at
the Office of the Commissioners of Patents, with his Petition, on
the 24th June 1872.
I, MICHAEL BURKE, of Liverpool, in the County of Lancaster, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
SCREW PROPELLERS," to be as follows:-
The object of my Invention is to provide a more efficient screw
propeller than those hitherto in use. For that purpose the blades
of a propeller of any ordinary or convenient form are constructed or
fitted with supplementary blades or bladelets. These may be formed
on the leading and following surfaces or on one of them only; they
may be of any desired width, and they may extend from the boss to the
tips of the blades, or part of the distance only.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Michael Burke in the Great Seal Patent Office
on the 24th December 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MICHAEL
BURKE, of Liverpool, in the County of Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of June, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Michael Burke, Her special licence that I,
the said Michael Burke, my executors, administrators, and assigns, or
such others as I, the said Michael Burke, 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 SCREW PROPELLERS,'
upon the condition (amongst others) that I, the said Michael Burke,
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 Michael Burke, 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 accompanying Sheet of
illustrative Drawings, and to the figures and letters marked thereon, that
is to say:-
The object of my Invention is to provide a more efficient screw
propeller than those hitherto in use. For that purpose the blades
of a propeller of any ordinary or convenient form are constructed or
fitted with supplementary blades or bladelets; these may be formed
on the leading and following surfaces, or on one of them only; they
may be of any desired width and they may extend from the boss to the
tips of the blades, or part of the distance only.

page_text: DESCRIPTION OF THE DRAWINGS.
Fig. 1 is an end elevation of the leading side of a propeller, and
Fig. 2 is a side elevation, both of a three-bladed screw propeller with
bladelets under my Invention, such bladelets being made about the full
length of the blades and shown cast on. Like letters denote the same
parts in both views.
a, boss; b, blades; and c, bladelets all cast in one piece. They may be
otherwise formed or constructed. The bladelets are here shown rising
gradually from the blades at 1 to the edges 2. The angle or sweep
may be varied. If necessary these bladelets may be cast separate and
secured by rivetting or otherwise to the blades.
As herein-before mentioned they may extend only a portion of the
distance from the boss to the tips of the blades and on one or both
sides; but in all cases they must run in straight or curved lines in the
direction of the length of the blades.
Having now described the nature of my said Invention, and par-
ticularized the same in such manner that others will be enabled to carry
my improvements into effect, I claim, the supplementary blades or
bladelets formed on or secured to the blades when such bladelets run in
straight or curved lines in direction from the boss to the outer ends of
the blades of screw propellers, all substantially as set forth.
In witness whereof, I, the said Michael Burke, have hereunto set
my hand and seal, the Twentieth day of December, in the year
of our Lord One thousand eight hundred and seventy-two.
In the presence of
JAMES JOHNSON.
MICHAEL BURKE. (L.S.)