IMPROVEMENTS IN SCREW PROPELLERS AND APPARATUS FOR GOVERNING ENGINES USED TO GIVE MOTION TO SCREW PROPELLERS
Year: 1858

page_text: LETTERS PATENT to Robert Griffiths, of 69, Mornington Road, Regent's
Park, in the County of Middlesex, Engineer, for the Invention of
"IMPROVEMENTS IN SCREW PROPELLERS AND APPARATUS FOR GOVERNING
ENGINES USED TO GIVE MOTION TO SCREW PROPELLERS."
Sealed the 2nd August 1858, and dated the 19th February 1858.
PROVISIONAL SPECIFICATION left by the said Robert Griffiths at the
Office of the Commissioners of Patents, with his Petition, on the 19th
February 1858.
I, ROBERT GRIFFITHS, of 69, Mornington Road, Regent's Park, in the
County of Middlesex, Engineer, do hereby declare the nature of the Invention
for "IMPROVEMENTS IN SCREW PROPELLERS AND APPARATUS FOR GOVERNING ENGINES
USED TO GIVE MOTION TO SCREW PROPELLERS," to be as follows:-
In screw propellers constructed in the ordinary manner, that is to say, so
that if a straight-edge is held against the blade and perpendicularly to the
length of the axis the straight-edge will touch the screw from end to end, it is
found that the back of the screw is quickly worn by the action of the water,
and this wearing of the screw doubtless represents an action retarding the
progress of the ship. In order to counteract this action, I so construct the
screw that if a straight-edge is laid on the propelling face of the blade in the
manner before described, it will be found that at a point at a distance from the
axis (generally of about half the radius of screw) the straight-edge and the blade
part company, the blade falling forward towards the ship or the screw may be so
constructed that the blade shall continually fall away from a straight-edge so

page_text: applied from the boss to the extremity of the blade; it will at the same time
be found on examining a screw constructed according to my Invention that if
a series of lines be drawn on the face of the blade, each of these lines
throughout its whole length being at the same distance from the axis, then
these lines will be identical with similar lines drawn on an "ordinary" screw
propeller of the same pitch, although in different planes.
In the Specification of a former Patent granted to me, there is described a
method of attaching the blades of screw propellers to the boss in such a way that
the pitch of the blade may be adjusted from time to time as may be required.
I now obtain this result in the following manner :-A key way is cut in the
stem of the blade and also in the boss, but that in the boss is larger than that
in the stem of the blade. When the propeller is dropt into its place a key is
driven in, and the extra space in the key way of the boss is filled by filling
pieces, and these are kept in their places by a covering plate. If it is required
to alter the pitch, the covering plate and the filling pieces are removed, and
the blade is moved the amount required; other filling pieces are then put
in, and the covering plate is replaced. In order to prevent the speed of the
engines from being injuriously increased, when, by the pitching of the ship the
screw is raised out of the water, I arrange at the stern of the ship a vertical
pipe open at the bottom to the sea, so that the water rises up in the pipe -to
the level of the water outside, and this column of water rises and falls as the
ship, pitches. The upper end of the pipe communicates by another pipe with
an apparatus placed near the engines, and so arranged that the variations of
pressure in the pipe cause the apparatus to act on a valve to cut off the steam
from the engine. The, apparatus. I prefer to employ consists of a cylinder
with a piston within it, which is connected with the valve so as to give the
desired motion.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Griffiths in the Great Seal Patent Office
19th August 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
GRIFFITHS, of 69, Mornington Road, Regent's Park, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Nineteenth day of February, in the year. of our Lord
One thousand eight hundred and, fifty-eight, in the twenty-first year of Her

page_text: 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 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 AND APPARATUS FOR GOVERNING ENGINES, USED TO GIVE MOTION TO
SCREW PROPELLERS," upon the condition (amongst others) that I, the said Robert
Griffiths, 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 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 follow-
ing statement thereof, that is to say:-
In screw propellers constructed in the ordinary manner, that is to say, so that
if a straight-edge is held against the blade and perpendicularly to the length
of the axis the straight-edge will touch the screw from end to end, it is found
that the back of the screw is quickly worn by the action of the water, and
this wearing of the screw doubtless represents an action retarding the progress
of the ship. In order to counteract this action I so construct the screw that
if a straight-edge is laid on the propelling face of the blade in the manner
before described, it will be found that at a point at a distance from the axis
(generally of about half the radius of screw) the straight-edge and the
blade part company, the blade falling forward towards the ship, or the screw
may be so constructed that the blade shall continually fall away from a straight-
edge so applied from the boss to the extremity of the blade; it will at the same
time be found, on examining a screw constructed according to my Invention,
that if a series of lines be drawn on the face of the blade, each of these lines
throughout its whole length being at the same distance from the axis, then:
these lines will be identical with similar lines drawn on an "ordinary" screw:
propeller of the same pitch although in different planės.
:
And in order that my said Invention may be most fully understood ande
readily carried into effect, I will proceed to describe the method in which I

page_text: build up the pattern for casting a screw or a screw blade according to my
improvements. I take a series of pieces of wood, by preference of the curved
form shewn in side view at Figure 1, and in edge view at Figure 2, and I mount
these pieces of wood on an axis, laying them one on the other until the pile is as
high as the greatest depth of the screw, that is to say, as the greatest vertical
distance (or distance measured on the shaft or on a line parallel to it) of the
front from the back edge of the screw. I then arrange these pieces of wood
so that each one projects a distance beyond the other according to the pitch of
the screw which it is desired to produce. Figure 3 shews a plan of the pieces
so arranged, and in this position they are glued together. From the screw
thus built up the form of blade desired is cut, the form which I prefer is that
indicated by red lines on the Drawing. Lastly, the model of a blade thus
formed is reduced to a uniform surface by cutting down the ridges formed by
the edges of the several pieces of wood. From the pattern thus produced the
screw blade is cast in the usual manner either in connection with a boss or
separate therefrom according to the method of construction adopted, and
in combining the propeller blade with its shaft or axis. It will be observed
that the blade produced in this manner springs from the axis in a direction
perpendicular to it, and then at a distance from the axis begins to fall away
from the perpendicular, following a curved line so as gradually to become
more and more inclined. The distance from the axis at which the blade
begins to depart from the perpendicular will depend on the length of the curve
in the pieces from which the pattern is built, and if this curve is carried up to
the axis, the blade will commence at the axis to fall away from the perpen-
dicular, and will become more and more inclined to it as the distance from the
axis increases. Care must be taken to turn the concave side of the blade
towards the ship, otherwise the propeller will work less advantageously than
an ordinary screw.
.
In the Specification of a former Patent granted to me, there is described a
method of attaching the blades of screw propellers to the boss in such a way
that the pitch of the blade may be adjusted from time to time as may be
required. I now obtain this result in the following manner :-A key way is
cut in the stem of the blade and also in the boss, but that in the boss is larger
than that in the stem of the blade. When the propeller is dropt into its place
a key is driven in, and the extra space in the key way of the boss is filled by
filling pieces, and these are kept in their places by a covering plate. If it is
required to alter the pitch, the covering plate and the filling pieces are
removed, and the blade is moved the amount required; other filling pieces are
then put in, and the covering plate is replaced.

page_text: Figure 4 is an end view partly in section, shewing a method of attaching
the blades of a propeller to the boss according to my Invention, and this is the
arrangement which I prefer to employ in ships not furnished with apparatus
for raising the screw. Figure 5 is a side view partly in section of the same.
Figure 6 is a plan; and Figure 7 is a section taken through the boss. The
boss of the propeller is of a globular form, and is constructed in several parts;
the central portion a contains the socket for the screw shaft a', and two
sockets at right angles to it, a², a³, to receive the shanks b, b, of the blades;
'the other portions of the boss c, c, are covers applied make up the boss as
nearly as may be to a perfect sphere, and which take no part of the strain,
they are fixed by screws to the central portion; the pieces c are each cast in
two parts and are bolted together afterwards, so that they may be more easily
removed if required; d, d, are keys passing through the shanks of the screw
blades, and also through key ways in the sockets a³, a², and these key ways
are of such a size as to allow the blades to be turned partially round after the
keys & are driven in, and the blade is thus placed at the exact angle to the
shaft required; the filling pieces e, e, which I prefer to be of hard wood, are
then put in, so as to fill up the spaces between the sides of the key way and
the key; a³, a³, are covering pieces or removeable parts of the central portion a
of the boss, and which are not put on until the keys and filling pieces are
adjusted; the covering pieces a³, a³, serve to prevent the filling pieces from
being displaced, and they are fixed in their places by bolts as is shewn ;
ff, are holes left just under the pieces a³, a³, to allow of the point of a crow-
bar being put under them when they have to be removed, and h, h, are holes
through these pieces to receive ropes to facilitate the removing and replacing
the pieces a³, a³, which operation frequently has to be performed when the
boss is submerged to a depth of eighteen inches or more.
Figures 8, 9, 10, and 11 shew views similar to those already described, of
screw blades fixed to their boss according to the method which I prefer for
ships furnished with apparatus for raising the screw; this arrangement differs
but little from that already described, the main difference is that the keys d, d,
run parallel to the shaft, and are accessible by removing the covers c, c; thus
the use of the moveable pieces a, a, is avoided, the filling pieces e, e, are
kept in their places by caps i, i, held up to them by keys j,j. In order to
prevent the speed of the engines from being injuriously increased, when' by
the pitching of the ship the screw is raised out of the water, I arrange at the
stern of the ship a vertical pipe open at the bottom to the sea, so that the
water rises up in the pipe to the level of the water outside, and this column
of water rises and falls as the ship pitches. The upper end of the pipe

page_text: communicates by another pipe with an apparatus placed near the engines,
and so arranged that the variations of pressure in the pipe cause the apparatus
to act on a valve to cut off the steam from the engine. The apparatus I
prefer to employ consists of a cylinder with a piston within it, which is con-
nected with the valve so as to give the desired motion. In carrying out this
part of my Invention, I arrange a vertical pipe or passage either within or at
the side of the stern post, and of about one square foot of sectional area.
From the upper end of this pipe a smaller pipe, say two inches in diameter,
passes to a cylinder in the engine room, this cylinder may conveniently be
about eight inches in diameter; the cylinder is open at one end and contains
a piston, the rod of which is connected with a throttle valve in the steam pipe;
the piston is furnished with a spring, which tends to keep it up to the open
end of the cylinder. The space in the cylinder behind the piston communicates
with the pipe or passage at the stern as before mentioned, and when the stern
rises, a partial vacuum is formed in the cylinder, and the piston is drawn back
until the vacuum is balanced by the tension of the spring, and the throttle
valve is thus acted. on so as to shut off the steam to a greater or less extent.
The strength of the spring and the length of its play I so regulate that when
there is about one foot of water over the screw, or more, according to the size
of the ship, the throttle valve shall be fully opened, and that when the boss
appears entirely above water, the throttle valve shall be completely closed;
when the depth is between these two extremes, the throttle valve is more or
less closed to an extent corresponding with the depth of water.
In witness whereof, I, the said Robert Griffiths, have hereunto set my
hand and seal, this Eighteenth day of August, in the year of our
Lord One thousand eight hundred and fifty-eight.
Witness,
JNO. ALCOCK.
ROBT GRIFFITHS. (L.S.)

page_text: LETTERS PATENT to Robert Griffiths, of 69, Mornington Road, Regent's
Park, in the County of Middlesex, Engineer, for the Invention of
"IMPROVEMENTS IN SCREW PROPELLERS AND APPARATUS FOR GOVERNING
ENGINES USED TO GIVE MOTION TO SCREW PROPELLERS."
Sealed the 2nd August 1858, and dated the 19th February 1858.
PROVISIONAL SPECIFICATION left by the said Robert Griffiths at the
Office of the Commissioners of Patents, with his Petition, on the 19th
February 1858.
I, ROBERT GRIFFITHS, of 69, Mornington Road, Regent's Park, in the
County of Middlesex, Engineer, do hereby declare the nature of the Invention
for "IMPROVEMENTS IN SCREW PROPELLERS AND APPARATUS FOR GOVERNING ENGINES
USED TO GIVE MOTION TO SCREW PROPELLERS," to be as follows:-
In screw propellers constructed in the ordinary manner, that is to say, so
that if a straight-edge is held against the blade and perpendicularly to the
length of the axis the straight-edge will touch the screw from end to end, it is
found that the back of the screw is quickly worn by the action of the water,
and this wearing of the screw doubtless represents an action retarding the
progress of the ship. In order to counteract this action, I so construct the
screw that if a straight-edge is laid on the propelling face of the blade in the
manner before described, it will be found that at a point at a distance from the
axis (generally of about half the radius of screw) the straight-edge and the blade
part company, the blade falling forward towards the ship or the screw may be so
constructed that the blade shall continually fall away from a straight-edge so

page_text: applied from the boss to the extremity of the blade; it will at the same time
be found on examining a screw constructed according to my Invention that if
a series of lines be drawn on the face of the blade, each of these lines
throughout its whole length being at the same distance from the axis, then
these lines will be identical with similar lines drawn on an "ordinary" screw
propeller of the same pitch, although in different planes.
In the Specification of a former Patent granted to me, there is described a
method of attaching the blades of screw propellers to the boss in such a way that
the pitch of the blade may be adjusted from time to time as may be required.
I now obtain this result in the following manner :-A key way is cut in the
stem of the blade and also in the boss, but that in the boss is larger than that
in the stem of the blade. When the propeller is dropt into its place a key is
driven in, and the extra space in the key way of the boss is filled by filling
pieces, and these are kept in their places by a covering plate. If it is required
to alter the pitch, the covering plate and the filling pieces are removed, and
the blade is moved the amount required; other filling pieces are then put
in, and the covering plate is replaced. In order to prevent the speed of the
engines from being injuriously increased, when, by the pitching of the ship the
screw is raised out of the water, I arrange at the stern of the ship a vertical
pipe open at the bottom to the sea, so that the water rises up in the pipe to
the level of the water outside, and this column of water rises and falls as the
ship, pitches.. The upper end of the pipe communicates by another pipe with
an apparatus placed near the engines, and so arranged that the variations of
pressure in the pipe cause the apparatus to act on a valve to cut off the steam
from the engine. The apparatus I prefer to employ consists of a cylinder
with a piston within it, which is connected with the valve so as to give the
desired motion.
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 August 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
GRIFFITHS, of 69, Mornington Road, Regent's Park, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Nineteenth day of February, in the year. of our Lord
One thousand eight hundred and fifty-eight, in the twenty-first year of Her

page_text: 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 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 AND APPARATUS FOR GOVERNING ENGINES USED TO GIVE MOTION TO
SCREW PROPELLERS," upon the condition (amongst others) that I, the said Robert
Griffiths, 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 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 follow-
ing statement thereof, that is to say :-
In screw propellers constructed in the ordinary manner, that is to say, so that
if a straight-edge is held against the blade and perpendicularly to the length
of the axis the straight-edge will touch the screw from end to end, it is found
that the back of the screw is quickly worn by the action of the water, and
this wearing of the screw doubtless represents an action retarding the progress
of the ship. In order to counteract this action I so construct the screw that
if a straight-edge is laid on the propelling face of the blade in the manner
before described, it will be found that at a point at a distance from the axis
(generally of about half the radius of screw) the straight-edge and the
blade part company, the blade falling forward towards the ship, or the screw
may be so constructed that the blade shall continually fall away from a straight-
edge so applied from the boss to the extremity of the blade; it will at the same
time be found, on examining a screw constructed according to my Invention,
that if a series of lines be drawn on the face of the blade, each of these lines
hroughout its whole length being at the same distance from the axis, then
these lines will be identical with similar lines drawn on an "ordinary" screw:
propeller of the same pitch although in different planes.
And in order that my said Invention may be most fully understood and
readily carried into effect, I will proceed to describe the method iu which I
:

page_text: build up the pattern for casting a screw or a screw blade according to my
improvements. I take a series of pieces of wood, by preference of the curved
form shewn in side view at Figure 1, and in edge view at Figure 2, and I mount
these pieces of wood on an axis, laying them one on the other until the pile is as
high as the greatest depth of the screw, that is to say, as the greatest vertical
distance (or distance measured on the shaft or on a line parallel to it) of the
front from the back edge of the screw. I then arrange these pieces of wood
so that each one projects a distance beyond the other according to the pitch of
the screw which it is desired to produce. Figure 3 shews a plan of the pieces
so arranged, and in this position they are glued together. From the screw
thus built up the form of blade desired is cut, the form which I prefer is that
indicated by red lines on the Drawing. Lastly, the model of a blade thus
formed is reduced to a uniform surface by cutting down the ridges formed by
the edges of the several pieces of wood. From the pattern thus produced the
screw blade is cast in the usual manner either in connection with a boss or
separate therefrom according to the method of construction adopted, and
in combining the propeller blade with its shaft or axis. It will be observed
that the blade produced in this manner springs from the axis in a direction
perpendicular to it, and then at a distance from the axis begins to fall away
from the perpendicular, following a curved line so as gradually to become
more and more inclined. The distance from the axis at which the blade
begins to depart from the perpendicular will depend on the length of the curve
in the pieces from which the pattern is built, and if this curve is carried up to
the axis, the blade will commence at the axis to fall away from the perpen-
dicular, and will become more and more inclined to it as the distance from the
axis increases. Care must be taken to turn the concave side of the blade
towards the ship, otherwise the propeller will work less advantageously than
an ordinary screw.
In the Specification of a former Patent granted to me, there is described a
method of attaching the blades of screw propellers to the boss in such a way
that the pitch of the blade may be adjusted from time to time as may be
required. I now obtain this result in the following manner :-A key way is
cut in the stem of the blade and also in the boss, but that in the boss is larger
than that in the stem of the blade. When the propeller is dropt into its place
a key is driven in, and the extra space in the key way of the boss is filled by
filling pieces, and these are kept in their places by a covering plate. If it is
required to alter the pitch, the covering plate and the filling pieces are
removed, and the blade is moved the amount required; other filling pieces are
then put in, and the covering plate is replaced.

page_text: Figure 4 is an end view partly in section, shewing a method of attaching
the blades of a propeller to the boss according to my Invention, and this is the
arrangement which I prefer to employ in ships not furnished with apparatus
for raising the screw. Figure 5 is a side view partly in section of the same.
Figure 6 is a plan; and Figure 7 is a section taken through the boss. The
boss of the propeller is of a globular form, and is constructed in several parts;
the central portion a contains the socket for the screw shaft a', and two
sockets at right angles to it, a², a³, to receive the shanks 6, b, of the blades;
the other portions of the boss c, c, are covers applied to make up the boss as
nearly as may be to a perfect sphere, and which take no part of the strain,
they are fixed by screws to the central portion; the pieces c are each cast in
two parts and are bolted together afterwards, so that they may be more easily
removed if required; d, d, are keys passing through the shanks of the screw
blades, and also through key ways in the sockets a³, a³, and these key ways
are of such a size as to allow the blades to be turned partially round after the
keys d are driven in, and the blade is thus placed at the exact angle to the
shaft required; the filling pieces e, e, which I prefer to be of hard wood, are
then put in, so as to fill up the spaces between the sides of the key way and
the key; a³, a³, are covering pieces or removeable parts of the central portion a
of the boss, and which are not put on until the keys and filling pieces are
adjusted; the covering pieces a³, a³, serve to prevent the filling pieces from
being displaced, and they are fixed in their places by bolts as is shewn ;
ff, are holes left just under the pieces a³, a³, to allow of the point of a crow-
bar being put under them when they have to be removed, and h, h, are holes
through these pieces to receive ropes to facilitate the removing and replacing
the pieces a³, a³, which operation frequently has to be performed when the
boss is submerged to a depth of eighteen inches or more.
Figures 8, 9, 10, and 11 shew views similar to those already described, of
screw blades fixed to their boss according to the method which I prefer for
ships furnished with apparatus for raising the screw; this arrangement differs
but little from that already described, the main difference is that the keys d, d,
run parallel to the shaft, and are accessible by removing the covers c, c; thus
the use of the moveable pieces a³, a³, is avoided, the filling pieces e, e, are
kept in their places by caps i, i, held up to them by keys j, j. In order to
prevent the speed of the engines from being injuriously increased, when by
the pitching of the ship the screw is raised out of the water, I arrange at the
stern of the ship a vertical pipe open at the bottom to the sea, so that the
water rises up in the pipe to the level of the water outside, and this column
of water rises and falls as the ship pitches. The upper end of the pipe

page_text: communicates by another pipe with an apparatus placed near the engines,
and so arranged that the variations of pressure in the pipe cause the apparatus
to act on a valve to cut off the steam from the engine. The apparatus I
prefer to employ consists of a cylinder with a piston within it, which is con-
nected with the valve so as to give the desired motion. In carrying out this
part of my Invention, I arrange a vertical pipe or passage either within or at
the side of the stern post, and of about one square foot of sectional area.
From the upper end of this pipe a smaller pipe, say two inches in diameter,
passes to a cylinder in the engine room, this cylinder may conveniently be
about eight inches in diameter; the cylinder is open at one end and contains
a piston, the rod of which is connected with a throttle valve in the steam pipe;
the piston is furnished with a spring, which tends to keep it up to the open
end of the cylinder. The space in the cylinder behind the piston communicates
with the pipe or passage at the stern as before mentioned, and when the stern
rises, a partial vacuum is formed in the cylinder, and the piston is drawn back
until the vacuum is balanced by the tension of the spring, and the throttle
valve is thus acted on so as to shut off the steam to a greater or less extent.
The strength of the spring and the length of its play I so regulate that when
there is about one foot of water over the screw, or more, according to the.size
of the ship, the throttle valve shall be fully opened, and that when the boss
appears entirely above water, the throttle valve shall be completely closed;
when the depth is between these two extremes, the throttle valve is more or
less closed to an extent corresponding with the depth of water.
In witness whereof, I, the said Robert Griffiths, have hereunto set my
hand and seal, this Eighteenth day of August, in the year of our
Lord One thousand eight hundred and fifty-eight.
Witness,
JNO. ALCOCK.
ROBT GRIFFITHS. (L.S.)