IMPROVEMENTS IN THE CONSTRUCTION OF STEAM SHIPS OR VESSELS, AND IN SCREW PRO- PELLERS
Year: 1872

page_text: LETTERS PATENT to Robert Griffiths, of Rhual Issa, Mold, in the
County of Flint, Engineer, for the Invention of "IMPROVEMENTS
IN THE CONSTRUCTION OF STEAM SHIPS OR VESSELS, AND IN SCREW PRO-
PELLERS."
PROVISIONAL SPECIFICATION left by the said Robert Griffiths
at the Office of the Commissioners of Patents, with his Petition,
on the 19th April 1872.
I, ROBERT GRIFFITHS, of Rhual Issa, Mold, in the County of Flint,
Engineer, do hereby declare the nature of the said Invention for
"INPROVENDENTS IN THE CONSTRUCTION OF STRAM SHIPS OR VESSELS, AND IN SCREW
PROPELLERS," to be as follows:-
-
This Invention relates, first, to further improvements in the con-
struction of steam ships of the character described in the Provisional
Specification of an Invention for which Letters Patent have been
granted to me, dated the 7th day of November 1871, No. 2991, for

page_text: "Improvements in the Construction of Screw Steam Ships and Pro-
pellers." In the said Provisional Specification a particular method of
constructing steam ships was described for the purpose of applying the
screw propeller at the bows; and the object of my present improvements
is the construction of steam ships for the purpose of applying the screw 5
propeller at the stern of the ship (as well as at the bows) in like manner
to that described in the said Provisional Specification for applying the
screw at the bows, such improved construction and arrangement being
applied either at the stern alone or at the bows alone, as may be found
most desirable, according to the requirements of the steam ship or 1
vessel.
In carrying out my present improvements at a suitable distance above
the keel, and below the water line, I form or leave openings in the side
or "counter" of the ship or vessel on each side of sufficient size, and
continued far enough within the body or hull of the vessel towards the 1
stern to allow of the placing of a screw propeller of suitable construction,
and for the purpose of supplying the water required for the screw to
propel the ship.
At the front of the screw propeller, and at the junction of the
openings above described, I place the forward stern post which carries 2
the screw shaft and the after bearing of the propeller, and to which
portions of the tubes or channels to conduct the water to the propeller
are attached.
At a suitable distance behind the propeller the after-stern post is
placed attached in the usual manner to the keel and framework of the 2
ship or vessel. This after stern post carries the rudder or rudders in the
usual manner, and to it also are secured portions of the tube or channel
in which the propeller revolves, and which conveys the water away from
the propeller. Or the after-stern post, and also the forward stem post,
may have the rudder post and rudder only.
I also propose in some cases to have two rudders placed one on each
side of the screw tube; or I may apply three rudders, one on each side
of screw tube, and one in front of centre of tube.
Twin screws may be employed in accordance with my improvements,
by having suitable tubes or openings formed on each side of the vessel 3
independently of each other, in each of which a screw propeller is

page_text: placed and arranged to revolve in suitable bearings, as is well under-
stood.
The supply of water to the screw propellers, arranged according to my
improvements, may be taken if desired from below the vessel on either
side of the keel instead of at the "counter," as previously described.
My improvements in scrow propellers consist in forming the blades
on the forward or leading edge curved backwards from about one-third
of their length from the boss to the point. The trailing or after edge of
the blades are also curved (but not parallel with the leading edge),
leaving the point of the blade about one-third the width of its root.
The blades are also bent forward towards the vessel, as described in
the Specification of a Patent granted to me, dated 19th February 1858,
No. 319.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Griffiths in the Great Seal Patent Office
on the 19th October 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
GRIFFITHS, of Rhual Issa, Mold, in the County of Flint, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of April, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
fifth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Griffiths, Her special licence
that I, the said Robert Griffiths, my executors, administrators, and
assigns, or such others as I, the said Robert Griffiths, 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 termi
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 OF STEAM SHIPS OR VESSELS, AND IN SCREW PROPELLERS,'
upon the condition (amongst others) that I, the said Robert Griffiths,
my executors or administrators, by an instrument in writing under
"

page_text: 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.
5
NOW KNOW YE, that I, the said Robert Griffiths, do hereby
declare the nature of the 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, that is to say :—
This Invention relates, first, to further improvements in the con-.1
struction of steam ships of the character described in the Specification
of an Invention for which Letters Patent were granted to me, dated the
7th day of November 1871, No. 2991, for improvements in the con-
struction of screw steam ships and propellers. In the Specification
of the said Letters Patent a particular method of constructing steam 1
ships was described, for the purpose of applying a screw propeller at the
bows, to be used with a propeller (an ordinary one) at the stern.
The object of my present improvements is the construction of steam.
ships for the purpose of applying a screw propeller at the stern of the
ship, generally in like manner to the way in which in the before- 2
mentioned Specification I described my Invention for applying a screw
propeller at the bows of the ship, and such improved method of applying
the screw propeller at the stern of the ship may be used either by itself
or in conjunction with the propeller at the bow of the ship. And whereas
in the before-mentioned Specification my improved application of the 2
propeller at the bows was stated to be used in conjunction with a screw
at the stern on the ordinary plan, and I have since discovered that it
may in certain cases be advantageous to use the particular method of
constructing steam ships described in the Specification of my Patent of
the 7th November 1871, for the purpose of applying a screw propeller 3
at the bows without any screw propeller at the stern.
This Invention has for its further object the application of such
improved arrangement of the screw propeller at the bows without the
use of any other screw propeller at the stern.
By applying screws to vessels in my improved manner, either at the 3
bow or at the stern, a much better effect is obtained than if the screws

page_text: -
.
were applied without such improvements, and when two such screws are
applied, one at the bows and one at the stern, a much larger driving
area can be bad for the propulsion of the vessel in a given draft of water
than can be obtained with a single screw at the stern in the ordinary
manner; moreover the use of two such screws, one each at the bow and
at the stern, coupled with rudders, enables me to turn the vessels with
great facility, which in many circumstances, especially in ships of war,
is of great advantage, and it also enables me in large vessels to drive
each screw with independent machinery, by which, in the event of
accident to either set of engines or to a propeller, I have still the power
of propelling the vessel by the uninjured propeller and its engines. For
these reasons it is found desirable to use my improved application of
screws, both at the bow and at the stern in the same vessel; but in
other instances, where the vessel has sufficient depth of water to receive
a screw of adequate diameter for the engine power contained in such
vessel, it may, on the score of simplicity and cheapness, be desirable to
use one only of my application of the propeller either at the bow or at
the stern.
Near the stern of the vessel (see Figures 1 and 2 of the accompanying
Drawings) I form a chamber a of sufficient capacity to receive, sur-
round, and admit of the working of the screw propeller 6. In front
of the propeller I place the forward stern post b' which carries the bearing
for the screw shaft c. The chamber a is split by this forward stern
post, and is made into two chambers or channels a', a', which have
3 orifices a³, a³, forward of the chamber a, such orifices being for the
inlet of the water to the screw propeller when the vessel is going
ahead. These orifices may be made either near to the kecl, as shewn in
the aforesaid Figures 1 and 2, or they may be made to come out at the
sides of the ship, as shewn for. the outlet orifices m in Figure 3.
Behind the screw propeller is placed the after stern post e. The
chamber a is divided into two at the after part, so as to give two
outlets d, d, one on each side of the after stern post for the efflux
of the water from the propeller when the ship is going ahead.
stern post; which is placed at a suitable distance behind the propeller, is
attached in the usual manner to the keel and framework of the ship, and
carries the rudder in the usual manner, and to it also are secured portions
of the tube or chamber in which the propeller revolves, and of the
channels which convey the water away from the propeller. Or a balanced
The after

page_text: rudder may be put round about the after stern post, or round about a
pintle or spindle forward of that post, so that when such rudder is put
hard over it shall close or nearly close one of the outlets by which the
water escapes from the screw when the vessel is going ahead.
Twin screws may be employed in accordance with my improvements 5
by having suitable tubes or openings formed on each side of the vessel
independently of each other, in each of which a screw propeller is placed
and arranged to revolve in suitable bearings, as is well understood.
The supply of water to the stern screw propeller or propellers arranged
according to my improvements, may be taken, if desired, from below the 1
vessel (as shewn in Figures 1 and 2 of the Drawing) on either side of
the keel as already described, or may be taken at the side in a similar
manner to that in which the escape of the water is shewn from the bow
screw in Figures 3 and 4, which represent the bow of the vessel.
::
Figure 5 represents the bow of a vessel constructed with the outlets 1
below for the water from the bow propeller.
6*, 6*, are stationary blades placed behind the screw propeller, against
which the water strikes as it is driven off by the propeller. These blades
I prefer to use in combination with the other arrangements described.
My improvements in screw propellers consist in forming the blades 2
on the forward or leading edge, curved backwards from about one-third
of their length from the boss to the point, as shewn at Figure 6 of the
Drawing.
The trailing or after edge of the blades are also curved (but not
parallel with the leading edge) leaving the point of the blade about one- 2
third the width of its root, I prefer that the blades should also be bent
forward, as described in the Specification of a Patent granted to me,
dated 19th February 1858, No. 319.
Having thus described the nature of my improvements, and the
manner of performing or carrying the same into practice, what I claim 3
is,-
First. The improved arrangement and construction of steam ships or
vessels, and the application of the screw propeller thereto at the stern
alone, substantially in the manner herein-before described and shewn in
the Drawing hereunto annexed.
8

page_text: Secondly. I claim the improved arrangement and construction of
steam ships or vessels and the application of the screw propeller thereto
at the bow alone, substantially in the manner herein-before described.
Thirdly. I claim the improved arrangement and construction of steam
ships or vessels and the application of the screw propeller thereto, both
at the bow and at the stern, substantially in the manner and for the
purposes herein-before described.
.
Fourthly. I claim the improved construction of screw propellers by
forming them in the manner herein-before described and shewn at
Figure 6 of the Drawing hereunto annexed.
In witness whereof, I, the said Robert Griffiths, have. hereunto
set my hand and seal, this Seventeenth day of October, in the
year of our Lord One thousand eight hundred and seventy-two.
5 Witness,
J. G. TONGUE,
Patent Agent,
ROB³. GRIFFITHS. (L.S.)
34, Southampton Buildings,
W.C.