AN IMPROVEMENT IN SCREW PROPELLERS
Year: 1868

page_text: LETTERS PATENT to James Albert Joyner, of Liverpool, in the County
of Lancaster, Master Mariner, and John Henry Jenkins, of the same
Place, Master Mariner, for the Invention of "AN IMPROVEMENT IN
SCREW PROPELLERS."
Sealed the 24th November 1868, and dated the 26th May 1868.
PROVISIONAL SPECIFICATION left by the said James Albert Joyner
and John Henry Jenkins at the Office of the Commissioners of
Patents, with their Petition, on the 26th May 1868.
We JAMES ALBERT JOYNER, of Liverpool, in the County of Lancaster,
Master Mariner, and JOHN HENRY JENKINS, of the same Place, Master
Mariner, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT IN SCREW PROPELLERS," to be as follows:-
The boss and blades of a screw propeller constructed according to
our Invention are of any usual or convenient form. Instead, however, of
the outer ends or tips of the blades being left free as heretofore has been
the practice, we connect and protect them by a circular flat hoop or

page_text: band, preferably of about the same width across its periphery as the
blades. The said hoop or band can be cast with the blades and boss
in one piece, or it can be affixed by rivets or otherwise fastened. Screw
propellers constructed as described act so as to propel a vessel through
the water at a greater speed with the same expenditure of power than
other propellers. Further advantages are, steering is facilitated and
vibration prevented.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Albert Joyner and John Henry Jenkins
in the Great Seal Patent Office on the 25th November 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JAMES
ALBERT JOYNER, of Liverpool, in the County of Lancaster, Master
Mariner, and JOHN HENRY JENKINS, of the same Place, Master Mariner,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-sixth day of May, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
first year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said James Albert Joyner and John Henry
Jenkins, Her special license that we, the said James Albert Joyner
and John Henry Jenkins, our executors, administrators, and assigns,
or such others as we, the said James Albert Joyner and John Henry
Jenkins, 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
"AN IMPROVEMENT IN SCREW PROPELLERS," upon the condition (amongst
others) that we, the said James Albert Joyner and John Henry Jenkins,
our executors or administrators, by an instrument in writing under our,
or their, or one of our or 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.

page_text: NOW KNOW YE, that we, the said James Albert Joyner and John
Henry Jenkins, do hereby declare the nature of our said Invention,
and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement thereof,
reference being had to the accompanying Drawings, and to the figures
and letters thereon, that is to say :-
The boss and blades of a screw propeller constructed according to our
Invention are of any usual or convenient form. Instead, however, of
the outer ends or tips of the blades being left free as heretofore has been
the practice, we connect and protect them by a circular flat hoop or
band, preferably of about the same width across its periphery as the
blades. The said hoop can be cast with the blades and boss in one
piece, or it can be affixed by rivets or otherwise fastened.
By the employment of screw propellers constructed as described a
vessel can be propelled through or over the water at a greater speed
with the same expenditure of power, or the same speed can be obtained
with less power; vibration so disagreeable to passengers and damaging
to ships cannot take place; fouling from ropes or seaweed is practically
impossible; and breakage of the propelling vanes or blades from
contact with canal banks, piers, or other structures, or with ice or
other floating bodies is scarcely possible.
On the accompanying Sheet of Drawings Fig. 1 is an end elevation,
and Fig. 2 an edge view of that modification of screw propeller which we
prefer.
In these views a is the boss, here shewn rounded; it may be made of
any desired form. b, the vanes or blades; these are shewn as having
a varying pitch, and they increase in width with the distance outwards
from the boss, but any convenient form can be given to them. c, the
flat hoop or band; this is not exactly cylindrical but resembles the
frustrum of a hollow cone, the leading side being preferably the one
of least diameter. We do not confine ourselves, however, to so
employing the screw as that the side of least diameter shall be the
leading side, our screw having a high efficiency when the leading
side is the one of greatest diameter.
Another modification is shown by Figs. 3 and 4, which are respectively
side and edge views.

page_text: a, the boss; b, flat 'yanes or blades; c, the hoop or band. The
blades or vanes are flat in this modification, and they project a short
distance on the leading side beyond the edge of the band or hoop.
It is highly important in all cases, however, that the width of the
hoop should be equal or nearly equal to the width of the vanes or
blades.
Both of the screws just described are of the cast kind, these being
the description most commonly in use; it will be obvious, however,
screws constructed as above set forth may be forged or built up of
plates and other pieces, or the boss and blades may be cast and the
flat band or hoop rivetted or otherwise secured thereto, or otherwise.
Having now described the nature of our said Invention, and
particularized the same so that others will be enabled to carry our
improvements into beneficial operation, we claim, constructing screw
propellers in the manner and for the purpose set forth.
In witness whereof, I, the said James Albert Joyner, have here-
unto set my hand and seal, this Eighteenth day of November
in the year of our Lord One thousand eight hundred and sixty-
eight
In the presence of
JOHN T. KING,
Patent Agent,
Liverpool.
JAMES ALBERT JOYNER. (L.S.)