IMPROVE- MENTS IN THE CONSTRUCTION AND MODE OF APPLYING SCREWS FOR PRO- PELLING VESSELS
Year: 1856

page_text: LETTERS PATENT to William Lynn, of Her Majesty's Dockyard, Ports-
mouth, Assistant Inspector of Machinery, for the Invention of "IMPROVE-
MENTS IN THE CONSTRUCTION AND MODE OF APPLYING SCREWS FOR PRO-
PELLING VESSELS."
Sealed the 19th August 1856, and dated the 20th February 1856.
PROVISIONAL SPECIFICATION left by the said William Lynn, at the
Office of the Commissioners of Patents, with his Petition, on the
20th February 1856.
I, WILLIAM LYNN, of Her Majesty's Dockyard, Portsmouth, Assistant
Inspector of Machinery, do hereby declare the nature of the said Invention
for IMPROVEMENTS IN THE CONSTRUCTION AND MODE OF APPLYING SCREWS FOR
PROPELLING VESSELS, to be as follows:-
These improvements refer to a novel mode of constructing the blades of
screw propellers, by which they may be seperately fitted on to or removed
from the shaft, for the purpose of being replaced in case of damage or from
any other cause, and by which peculiarity of construction spare screws can be
more conveniently stored or carried on board of ship.
Instead of casting the blades of the screw together with the boss and shaft,
or, as is frequently done, casting them solid with the boss, the eye of the screw
being afterwards bored and fitted upon the shaft, my improvements consist in
casting the blades seperately with a portion only of the length of the boss

page_text: or eye cast therewith, and afterward fitting the parts of the boss together in
such a manner as to secure them to the shaft and form a solid screw when
keyed up or fixed by collars. Thus, for instance, in applying my Invention
to a double-bladed screw, I form the boss in the manner of jointing hinges, viz.,
with a nuckle joint, the boss being divided in its length into, say, four parts.
The male portion is formed in the middle of the boss of one blade, and is
about ths of the whole; whilst the other blade has the female portions of
the boss divided into two lugs or cheeks, each of about 1/4th of the male and
female portions of the boss, being accurately fitted together. The eye is made
to receive the screw shaft or T-headed piece of shaft, upon which it is fitted,
and may be secured by means of a feather.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Lynn in the Great Seal Patent Office on the
20th August 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
LYNN, of Her Majesty's Dockyard, Portsmouth, Assistant Inspector of Ma-
chinery, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of February, in the year of our Lord
One thousand eight hundred and fifty-six, in the
year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said William Lynn, Her special licence that I, the said William Lynn, my
executors, administrators, and assigns, or such others as I, the said William
Lynn, 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
CONSTRUCTION AND MODE OF APPLYING SCREWS FOR PROPELLING. VESSELS, upon
the condition (amongst others) that the said William Lynn, by an instru-
ment in writing under his, or their, or one of their hand and seal, 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 imme-.
diately after the date of the said Letters Patent.

page_text: .
NOW KNOW YE, that I, the said William Lynn, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say:-
These improvements refer to a novel mode of constructing. the blades of
screw propellers, by which they may be seperately fitted on to or removed
from the shaft, for the purpose of being replaced in case of damage or from
any other cause, and by which peculiarity of construction spare screws can be
more conveniently stored or carried on board of ship.
Instead of casting the blades of the screw together with the boss and shaft,
or, as is frequently done, casting them solid with the boss, the eye of the screw
being afterwards bored and fitted on the shaft, my improvements consist in
casting the blades seperately, with a portion only of the length of the boss
or eye cast therewith, and afterwards fitting the parts of the boss together in
such a manner as to secure them to the shaft, and form a solid screw when
keyed up or fixed by collars. Thus, for instance, in applying my Inven-
tion to a double-bladed screw, I form the boss in the manner of jointing
hinges, viz., with a nuckle joint, as shewn in the accompanying Drawing,
the boss being divided in its length into, say, four parts. The male portion
is formed in the middle of the boss of one blade, and is about 3/4ths of the
whole; whilst the other blade has the female portions of the boss divided into
two lugs or checks, each of about 4th, the male and female portions of the
boss, being accurately fitted together. The eye is made to receive the screw
shaft or T-headed piece of shaft, upon which it is fitted, and may be secured by
means of a feather.
In the accompanying Drawing, Figs. 1, 2, 3, 4, 5, and 6 exhibit various views
of the blades of my improved screw propeller in different positions, and which
from their simplicity and distinctness need no minute explanation.
Fig. 7 is a side view of a short T-headed piece of shaft, the T-piece of
which takes into a groove or slot in the end of the screw shaft. The same
letters of reference indicate corresponding parts on each Figure relating to
the improved screw propeller.
a is the one blade having the single nuckle or male portion of the joint b;
a' is the corresponding blade, having the double nuckle or female portion of
the joint c, c; d, the eye or hole through the boss of the screw blades; e, the
shoulder of the single nuckle or male portion of the joint or boss, and which
abutts on and forms a stop into the recess formed upon the top sides of the
double nuckles or female portions of joint or boss.

page_text: In Fig. 7, f is that portion of the shaft upon which the boss of the screw
is fitted, there being a feather thereon, which fits or takes into the slot or
groove made in the eye or hole d of the boss of the screw blades; g is the
shouldered end or outer bearing piece for supporting the weight of the screw,
h being another or inner bearing or journal; i is the T-head, which takes into
a slot in the end of the screw shaft, and by which the screw is propelled or
caused to revolve.
Although I have shown a double-bladed screw, I do not confine myself to
that number, but apply the same principle of construction to other forms of
screw and other numbers of blades. And I do not confine myself to the fitting
of seperate blades (made according to my Invention) on to a T-headed short
shaft, as they may be fitted directly on to the outer end of the main screw
shaft or otherwise; but I claim as my Invention the construction of the blades
of screw propellers in the manner described.
In witness whereof I, the said William Lynn, have hereunto set my
-hand and seal, this Thirteenth day of August, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
WILLIAM SMITH, C.E.,
.
10, Salisbury St, Adelphi, London.
WILLIAM LYNN. (L.S.)