IMPROVE MENTS IN THE MANUFACTURE OF SCREW PROPELLERS
Year: 1869

page_text: LETTERS PATENT to Charles Henry Murray, of Loman Street, in the
Borough of Southwark, Machinist, for the Invention of "IMPROVE
MENTS IN THE MANUFACTURE OF SCREW PROPELLERS."
Sealed the 25th January 1870, and dated the 8th September 1869.
PROVISIONAL SPECIFICATION left by the said Charles Henry Murray
at the Office of the Commissioners of Patents, with his Petition, on
the 8th September 1869.
I, CHARLES HENRY MURRAY, of Loman Street, in the Borough of
Southwark, Machinist, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN THE MANUFACTURE OF SCREW PROPELLERS," to be as
follows:-
My Invention of improvements in the manufacture of screw
propellers has for its object to construct these articles of wrought iron

page_text: or steel, so that they may be stronger and lighter than cast-iron
propellers.
The main objection to making screw propellers of wrought metal is
the difficulty of forging such peculiarly shaped articles. I obviate this
difficulty by forging the arms of the propellers in two or more parts, and
when these pairs of arms are mounted on their common shaft they are
connected together by sheet iron which forms the blades.
I do not confine myself to any particular form of propeller, in fact
the form of the blades constitutes no part of my Invention, which is
confined simply to a novel and easy mode of constructing any kind of
screw propeller,
In carrying out my Invention in the manufacture, for example, of a
two-bladed propeller, I forge two pair of arms of similar form, and each
provided with a boss, through which passes the propeller shaft. When
these arms are mounted on the shaft they are to be placed at the required
angle to each other so as to produce when the blade is secured thereon
the desired helical twist. When the arms are properly placed they may
be secured together by shrinking an iron ring on their bosses. Pro-
pellers with three, four, or more blades may be constructed in the same
manner in two separate parts, which will be connected together by the
sheet iron blades,
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Henry Murray in the Great Seal Patent
Office on the 8th March 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
HENRY MURRAY, of Loman Street, in the Borough of Southwark,
Machinist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of September, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Charles Henry Murray, Her special
licence that I, the said Charles Henry Murray, my executors, adminis-

page_text: trators, and assigns, or such others as I, the said Charles Henry Murray,
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 THE MANUFACTURE OF SCREW PROPELLERS," upon the con-
dition (amongst others) that I, the said Charles Henry Murray, my exe.
cutors 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 Charles Henry Murray, 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 Drawing here-
unto annexed, and to the letters and figures marked thercon (that is to
say):-
My Invention of "Improvements in the Manufacture of Screw Pro-
pellers" has for its object to construct these articles of wrought iron or
steel, so that they may be stronger and lighter than cast-iron propellers.
The main objection to making screw propellers of wrought metal is
the difficulty of forging such peculiarly shaped articles, and the object of
the present Invention is to obviate this difficulty, which I do by forging
the arms of the propellers in two or more parts, and when these parts
or pairs of arms are secured on their common shaft by shrinking them
on or otherwise securing them they are connected together at their
outer ends by sheet iron, which forms the blades or operating surfaces of
the propellers.
I do not confine myself to any particular form of propeller, nor to
the number of blades of which the propeller may be composed, in fact
the form or number of the blades constitutes no part of my Invention,
which is confined simply to a novel and easy mode of constructing any
kind of screw propeller of wrought iron or steel.

page_text: In the accompanying Drawing I have shewn the modes I prefer for
carrying out my Invention in the manufacture, for example, of a two-
bladed propeller, which is shewn in elevation at Fig. 1, it is formed of
two pairs of arms a, a, of wrought iron, and of nearly similar form.
One of these is shewn in front elevation at Fig. 2, while Fig. 3 repre-
sents the two arms combined, ready to receive the blades or propelling
surfaces. Each arm is provided with a boss a¹ through which passes
the propeller shaft. When these arms are mounted and secured on
their shaft, they are to be placed at the required angle to each other as
shewn at Figures 1 and 2, so as to produce (when the blades b, b, Fig. 1
are secured thereon), the desired helical twist to form a screw propeller.
When the arms are properly placed they may be secured together by
shrinking an iron ring on their bosses or in any other convenient manner.
Propellers with three, four, or more blades may be constructed in the
same manner in two separate parts, which will be connected together
by the sheet iron blades b, b.
Fig. 4 is a front elevation of a propeller, in which the two arms a, a,
shewn in edge view and elevation at Figures 5 and 6, are shrunk on to
a sleeve shaft c, Fig. 7, which is provided with a central washer c¹ to
keep the bosses of the arms a, a, a sufficient distance apart. The pro-
pelling surfaces or blades are secured on the arms by rivetting as shewn
in the Drawing or they may be welded on or fixed in any other con-
venient manner.
Figures 8, 9, 10, and 11 are various views representing another form of
arms for propellers, Fig. 8 is a side view of the propeller, and Fig. 9
an end view; Fig. 10 is an elevation of one of the arms a detached, and
Fig. 11 is a vertical section of the propeller, from which it will be
seen that the bosses form a central butt joint, and are held together by
a ring 2, 2, which is shrunk on; Figures 12 and 13 are side and end
views of a propeller in which the bosses are provided with ears or
flanges 3, 3, which may be secured together by means of bolts and nuts
as shewn in the Drawing.
Having now described my Invention of improvements in the manu-
facture of screw propellers," and having explained the manner of
carrying the same into effect, I claim as the Invention secured to me
by Letters Patent as aforesaid, forming screw or stern propellers of
wrought iron or steel arms forged separately as herein set forth, and

page_text: then mounted on a common shaft, and held together by their bosses and
by the blades or propelling surfaces wliich are rivetted on the arms or
are welded or otherwise secured thereto.
In witness whereof, I, the said Charles Henry Murray, have here-
unto set my hand and seal, the Eighth day of March, in the
year of our Lord One thousand eight hundred and seventy.
CHA³. H. MURRAY. (L.S.)