IMPROVEMENTS IN PROPELLING AND STEERING SHIPS, AND IN APPARATUS OR MECHANISM EMPLOYED THEREFOR
Year: 1879

page_text: LETTERS PATENT to John Lorimer Corbett, of Glasgow, in the County of
Lanark, and William Young Fleming, of Gourock, in the County of Renfrew,
North Britain, for the Invention of "IMPROVEMENTS IN PROPELLING AND
STEERING SHIPS, AND IN APPARATUS OR MECHANISM EMPLOYED THEREFOR.”
Sealed the 2nd May 1879, and dated the 14th February 1879.
PROVISIONAL SPECIFICATION left by the said John Lorimer Corbett and
William Young Fleming at the Office of the Commissioners of Patents on the
14th February 1879.
IM-
JOHN LORIMER CORBETT, of Glasgow, in the County of Lanark, and WILLIAM
YOUNG FLEMING, of Gourock, in the County of Renfrew, North Britain.
PROVEMENTS IN PROPELLING AND STEERING SHIPS, AND IN APPARATUS OR
MECHANISM EMPLOYED THEREFOR.'
"
This said Invention has reference to a new or improved combination of construc-
tion and arrangement of the parts of the screw propeller and its bearing or carrying
frame and actuating mechanism of steam ships or vessels which by special hand
steering and controlling gear or mechanism connected with the propeller have great
merit and advantage in controlling the speed and steering the ship either back-
wards or forwards at any moment without reversing the steam or propelling
engines, or directly interfering with these. And the nature and novelty of the
Invention of improvements consist in constructing and fitting or mounting the
screw propelling blades (proferably two in number) to oscillate on a central trans-
verse radial spindle through their boss and driving spindle, or on separate centres
on opposite sides of the boss; so as to be made to swivel on such spindle or axis to
any angle within 3rd or 4th of a revolution to give any approximate pitch of screw
desired either to propel the ship forwards or backwards, all upon a special short
screw propeller shaft mounted in bush bearings at each end some little distance
outside the boss of the blades in a strong open frame, made to oscillate or be
swivelled round on vertical spindle and footstep bearings in the manner of a rudder
either at the extreme end of the stern keel or within a recess or well formed
therein for it in front of the stern post when a rudder is used. The swivelling of
this propeller frame is effected above deck or on board the ship by the strong upper
[Price 6d.]

page_text: .
spindle projecting up through a lever or segmental screw wheel and screw nana
shaft at its top end to port or starboard the screw shaft and its frame, and cause it
to veer the ship through the direct action or force of the screw propeller as an
equivalent for or in addition to the ordinary rudder when that is used. And for
the purpose of allowing the short-screw shaft to oscillate as stated it is connected
at the near or driving end by a universal joint to the stern end of the screw shaft
passed-out.from the engines through a stern bearing and water-tight stern pipe as
-usual.—The universal joint_might be of an improved form, as that of a solid ball
_on_the_near_end_of_one_shaft and a corresponding socket in the other, coupled-by-a
-strong-radial-pin-or-cotter-passed-through the rim of the socket and a longitudinal
slot in the ball, which would transmit the motion and power and allow of the
-universal swivelling action, and also take the thrust off the screw in propelling
forwards; or when a collar thrust bearing is fitted at the neck of the screw shaft
in the upright of its swivelling and carrying. frame behind the universal joint this
might be formed by a short double ball joint piece, each ball working in a corre-
sponding semi-hollow ball socket in the near end of each shaft, each coupled as
stated in reference to the single ball and socket by a cross pin or cotter in the socket
end and slot in the ball, which double arrangement allows of a greater oscillation or
angular action of the screw frame, with greater freedom and strength of the ball
and socket parts of the joint from the frame carrying the screw propeller requiring
to oscillate on its vertical axis through the centre of the ball and socket in the
single arrangement, while the double arrangement allows room between the two
balls for the angular action of the ends of the sockets or shafts. The oscillation of
the screw blades may be given by a single eccentric or crank pin in the case of the
two opposite blades being on the one centre (and of a screw angle of about 45° at
the mean acting surface oscillated through 90°) by a collar sleeve sliding on the
outer end of the screw shaft with a straight slot and feather and connecting link,
or scroll slot or pin, or a crank pin on each blade connected by separate links or
scroll grooves to the sleeves, which would be shifted or oscillated to and fro on
the shaft to swivel the blades by a forked lever fulcrumed on the back or forward
vertical post of the frame carrying the journal bearings of the screw shaft, this lever
being actuated by a horizontal rod or slide at the upper open part of the frame,
connected and actuated by a crank pin on the lower end of a spindle, preferably
passed up through the swivelling or hinged spindle (made hollow for the purpose)
of the frame carrying the screw propeller and all these moving fittings, this inner
spindle being fitted with a moving and setting hand lever or a screw wheel segment
and hand screw working in it, all on the upper lever and actuating segment of the
hollow spindle of the oscillating frame, so that the person steering the ship by this
improved arrangement may also control the pitch of the screw for propelling full
speed forwards or backwards, or at any intermediate speed between these, desired
at any time, all without reversing or slowing the speed of the steam engines. Other
equivalent arrangements of mechanism might be employed for swivelling the screw
blades of the propeller, such as a sliding or oscillating spindle working in through
the back end of the propeller shaft, bored or made hollow for that purpose,-and-by
a slot and pin or cotter connection through the propeller shaft, or a scroll or, wedge
action made to swivel the screw propeller blades in an equivalent manner to that
When the screw propelling
described by the sleeve on the outside of the shaft.
blades are made at other angles and mounted on separate radial spindles these might
have large holding heads or bosses on them to swivel within the propeller boss, by
which they might be turned in the same or opposite directions when the oscillating
mechanism is fitted within the boss, as stated, and as has been done in some other
arrangements of screw propeller. blades. which have been made to swivel for merely
altering the pitch of the screw, but not for making the screws to propel both in the
forward and backward direction. The swivelling screw blades of this new or
improved combination of forward and backward propelling and steering screw
propeller may be made of any of the ordinary constructions and material, as of
malleable cast iron or steel, or of forged iron or steel out of the solid, or built o

page_text: plates, but preferably the latter, of a true screw on the front and forward acting
surface to the mean pitch desired to suit the power and velocity of the engines in
relation to the speed of the ship, so that when the blades have to be increased in
pitch or diminished the slight non-conformity of the curve of the surface of the blade
will not much or practically injure the effective working of the screw in their
abnormal positions, but for the forward action it is preferred to have the blades
made with a less or finer pitch towards the boss and to keep them as clear of that
as possible, also at the lower and outer edges and surfaces to give freedom there for
the free escape of the water backwards to prevent the power of the propeller being
spent in churning or swirling the water at the boss.
Although these improvements are not so convenient for three or four blades these
could be fitted in accordance with this Invention also by making or mounting the
three blades on one boss, equally divided round it, and having a separate eccentric
pin or swivelling arrangement, as described, for each blade; or for the four blade
arrangement two blades may be mounted on one side of one swivelling spindle or
eye and two on the other side on a corresponding spindle, the one blade of each in
advance of the other, and with their acting surfaces parallel to each other some
distance apart, as the sectional segment of a double threaded screw; or otherwise,
a second set of opposite screw blades on axes at right angles to each other, the one
set on a boss sufficiently in advance of and so as to swivel clear of each other, all
otherwise in both these four bladed arrangements substantially as described in
reference to the two-bladed arrangement, and all on the short screw shaft so as to
revolve within the hollow swivelling frame carrying the whole, and at any required
angle within 90° to port or starboard to propel and steer the ship by the screw
propeller at the same or slower speed, and reverse or back the ship by the person
in charge, all without requiring to lose time in signalling the engineers or reversing
or stopping the steam engines.

page_text: JOHN LORIMER CORBETT, of Glasgow, in the County of Lanark, and WILLIAM
YOUNG FLEMING, of Gourock, in the County of Renfrew, North Britain. "IMPROVE-
MENTS IN PROPELLING AND STEERING SHIPS, AND IN APPARATUS OR MECHANISM
EMPLOYED THEREFOR."_
Our said Invention has reference to a new or improved combination or construc-
tion and arrangement of the parts of the screw propeller and its bearing or carrying
-frame and actuating mechanism for steam ships or vessels, and with special hand
steering and controlling gear or mechanism directly connected to the propeller, has
great merit and advantage in controlling the speed of the ship either backwards or
forwards, as well as in steering it, all at any moment, without reversing the steam
or propelling engines or directly interfering with these.
And the nature and novelty of the Invention or improvements consist generally
in constructing and fitting or mounting the screw propelling blades A (preferably
two in number, but it might be three or four), each on a central spindle or axis a,
transverse or radial to or through their driving boss B and main shaft C, and on
opposite sides thereof.
All so that the blades A are made to swivel on their said spindles or axes a to
any required angle, as within a third (/s) or a fourth (1) of a revolution, to give
any desired approximate pitch of or to the screw or blades A, either to propel the
ship forwards or backwards. The blades A are fitted in their boss B upon a special
short screw propeller shaft C, mounted in bush bearings e, e¹, at each end, some
little distance outside the boss B, in a strong open frame D, which is made to
oscillate and be swivelled round on a vertical axis or spindle in upper and lower
bearings d, d, to the stern post Z of the ship Z (much in the same manner as a
rudder frame), preferably at the extreme end of the stern keel Z. But this might
be done within a recess or well formed therein for it in front of the stern post Z',
when a rudder is desired to be used behind this propeller, which is not necessary
with this new propeller, which also steers as well as propells the ship. The swivel-
ling of this frame D (as well as the propeller A, B, and its driving shaft C, which it
carries,) is effected above deck or on board the ship at z, z, by the strong upper
spindle D¹, preferably made hollow, and fitted at the top end with a strong screw
wheel or segment E and screw shaft E¹, with hand steering wheel El mounted on
a frame z on the deck 2¹. All so as to port or starboard the frame D, D', and the
screw propeller shaft C, and cause it to veer the ship Z through the direct action or
force of the screw propeller, as an equivalent for or in addition to the ordinary
rudder when that is used. But other ordinary arrangements of hand or motive
power steering gear used for rudders might be employed.
--In-order-that-the-full-nature-of-our-said-Invention,-and-mode-and-means-of-
putting the same into effect or practice, may be properly understood, we will now
proceed to particularly describe the several Figures on the Sheet of Drawings
which we have hereunto appended for that purpose, the same reference letters and
numerals indicating the same or like parts in all the Figures where shown. Figure 1
is a side elevation of the after end of a screw steam ship Z, Z, partially in section,
as fitted with one complete modification or general construction and combination of
the parts of our said new or improved screw propeller A, B, C, D, and its motive and
controlling arrangement of gear or mechanism for propelling and steering the ship
simultaneously. And Figures 2 and 3 are a vertical end view and section, taken
on the line 1-1 of and corresponding to Figure 1 of the propeller A, B, C, and its
swivelling carrying frame D. While Figures 4, 5, and 6 are horizontal sections of
the same propeller, as taken near the lines 2--2, 3--3, and 4 - - 4, respectively in
Figure 1, to show the details and fittings of the internal moving and controlling

page_text: parts of the propelling blades A, A, more clearly. Figure 7 is a side elevation,
partially in section, of the after or stern part of a steam ship Z, Z, as fitted with a
complete modification or general construction and combination of the parts of our
said new or improved propelling and steering propeller, slightly different from the
modification and arrangement shown in Figures 1 to 6. And Figures 8 and 9
are an end view and a vertical section on the line 5 - of Figure 7; while Figures
10, 11, 12, and 13, are various horizontal sections and a plan of the arrangement
shown in Figure 7, and taken on the respective lines 6-6, 7--7, and 8. 8 of that
Figure; and Figure 14 shows a side elevation, partly in section, of a different
modification of the screw blades A, A, mounted on fixed axes a, a, on the opposite
sides of its propeller shaft C without a boss B, and swivelled on the outside by the
eyes A¹ of the blades A somewhat differently from that shown in the former Figures.
Referring to Figures 1 and 7, the screw shaft C is connected at the near or driving
end e so as to allow it to be swivelled with its carrying frame D on the axis d, d,
by a universal joint as 22, 21, to the stern end of the screw shaft F passed out from
the engines through an ordinary stern bearing F1, and water-tight stern stuffing
box pipe E, as usual.
This universal joint may by one arrangement be of the improved construction,
shown in Figure 7 of the Drawings, namely, having a solid balle formed on the
near end of the shaft C, and a hollow socket f corresponding and fitting it on the
back end of the shaft F, the two parts c and f being coupled by a strong cross
radial pin or cotter c¹ secured through the rim of the socket f, and passing loose
through a longitudinal slot c¹¹ in the solid ball c, and which would transmit the
motion and power, and at the same time allow the universal swivelling action of
the joint to take place. In this case the ball and socket c, f, would take part of the
thrust of the screw in propelling forwards; but when a collar thrust bearing e is
fitted at the neck of the screw shaft C in the upright of its swivelling and carrying
frame D, this night take the thrust behind the said ball joint c, f, in which case
the universal joint might be formed, as shown at ¹, in Figures 1 and 5, by a short
double ball joint piece c*, cx, each ball c working in a corresponding hollow semi-
spherical socket f, f, on the adjacent ends of the shafts C and F, each spheroidal
joint c, f, being coupled by a cross pin or cotter and slot c¹, c¹¹, as stated in reference
to the single ball and socket joint coupling c, f, described in reference to Figure 7.
This double arrangement of ball and socket joint c*, cx, allows of greater strength
of the neck of the ball and socket parts cx, f, for the free angular oscillation of the
joint and the frame D carrying the screw propeller A, B, C, and which is fitted so
as to oscillate on its strong vertical axis d, d, in a vertical line through the centre
of the ball and socket joint in the single arrangement, Figure 7; or the centre
between the balls c*, c*, in the double arrangement, shown in Figure 1, which
lessens the angular action and strain and friction on the ball and socket joints c*, f,
at the end of the shafts C and F. To enable the blades A, A, of the screw pro-
peller to be feathered or to give the required pitch or angle in reverse directions to
propel the ship forwards or backwards, or feather the blades to give the least
propelling action in a line with the keel, or at right angles thereto in accordance
with our improvements without stopping the motive engines as herein before stated,
they are swivelled, as seen dotted-in particularly in Figure 5, giving an angular
oscillation of, say, 90°, with the blade shown in the mean acting position of about
45. Various arrangements may be adopted for the fitting of the blades A, A, on
their carrying shaft C or boss B, somewhat analogous to that employed for ordinary
feathering screw propellers, which have never heretofore been made to swivel in
their carrying frame as a rudder frame D. By one arrangement, when two or four
blades A are employed, the two opposite blades as A, A, might be mounted on a
single solid transverse axis or spindle (as a), swivelling in a bearing right through
the shaft C or boss B, so that one crank pin, as a², on the neck socket or flange A¹
outside, would, by a single connecting rod (as a) oscillate each pair of opposite
blades by an arrangement of sliding collar sleeve, as a, seen in Figure 14 of the
Drawings, in which however a pin a' and connecting rod a is fitted to each

page_text: blade A and A as they are made to oscillate on fixed radial axes a, a, projecting
out from the driving shaft C the sleeve collar a¹¹ being guided in its longitudinal
'sliding action on the shaft C by slots working over and past these axes a, a. In
this arrangement, Figure 14, the sliding ring, groove, collar, sleeve, or boss all (to
which.the.outer free ends of the rods all are attached for swivelling the blades A) is
shifted to and fro by the ring slide e fitted in its groove and guide e² on the
stern upright of the frame D₁, and moved by an arrangement of lever and rack
-gearing-mechanism G,-G!, GH, G2, as seen-more particularly in Figures 1 to 5, to
the-desired-angle-as-dotted-in-in-Figure 5.-
Referring-to-the-arrangement-shown-in-Figures-1-to_6_the_blades. A, A, are
mounted to swivel in their large-hollow-boss-B-by-stems-a-swivelling-in-inner-and
outer bearings, with an outer collar a³ and screwed on washer or gland a¹ for
securing them to the boss B¹, and allow of their free oscillation by the crank and
pin a secured on their spindle a inside the hollow boss B, these pins a working
direct into transverse slots in the inner ends of the sliding collar boss B' (equiva-
lent to the collar sleeve all of the modification shown in Figure 14), but in this
case working within the hollow boss B, through its back end actuated by the
slide e. This slide e¹ is connected to the lower end of the lever G, which is
fulcrumed on a strong bracket g on the back upright D of the frame D, and
connected at the upper end to the sliding bar or rack G¹ fitted in the guides g' on
the upper edge D₁ of the frame D. The toothed rack part G₁ of this rod G¹,
which works through a recess in front of the hollow spindle D¹ of the frame D, is
actuated by a small toothed wheel G2 on the lower end of the vertical spindle H
working in a footstep bearing h at the lower end and journal bearing h¹ in the top
or cover of the hollow spindle D', and fitted with a horizontal hand wheel H on
the top outside for being turned by the steersman working the steering wheel Eu
of the gearing for oscillating the frame D, and propeller A, B, C, for steering and
propelling the ship. Thus by these improved arrangements, enabling the pitch of
the screw to be altered and controlled to propel the ship at full speed, or any
intermediate slower speed, forwards or backwards, or feather the blades and stop
the speed all together, as desired at any time; all without reversing or slowing
the speed of the steam engines, by simply turning the wheel H' to alter the pitch
of the screw blades A, A, as before described. A pointer is fitted on the top h¹
with a circular index divided round the cover on the wheel H' to indicate the
pitch or angle of the blades; and an arrangement of screw and screw wheel might
be used, or a holding catch lever which would retain the shaft and wheel H, H¹, in
the position to which they were set, and also retain the blades A, A, at the pitch
or angle they were set to by the turning of these and the shifting of their slide B¹.
The screw blades A, A, shown in Figures 1, 3, and 5, are formed widest, and of an
increasing pitch, as they extend from their stem A¹ outwards to the periphery, as
we have found this to give the best effect with our experimental models. Referring
to the arrangement shown in Figures 7 to 13, the blades A, A, are of an ordinary
truly punched straight screw, narrowing towards the outer periphery, such as used
-by-Griffiths-and-in-other-ordinary-swivelling-or feathering. blades; and they are
fitted to their boss B much in the same manner as shown in Figure 1, but have
their moving crank pin a¹ of each connected by a link or rod all to lateral pins in
& collar a² sliding on the back end of the shaft C within the hollow boss B, and
connected by a cotter and slot to a central rod all sliding and passed in through
the back end of the shaft C, bored or made hollow for that purpose, and connected
outside by a grooved collar boss a to the lower end of the lever G made forked
for that purpose; and fitted with, and actuated by the rack G¹, G¹¹, and central
shaft H, and hand wheel H at the top of the main hollow spindle D¹, all other-
wise substantially as described in reference to Figures 1 to 5, so as to feather the
blades at will to the desired effective pitch for propelling or backing the ship. In
this arrangement the position of the blades are locked or fixed to the position or
angle they are set by the sliding rod i mounted on the back end of the frame D
over the central spindle a!, so as to take into shifting. notches at el when raised

page_text: by the links at the top of the slide catch i linked to the outer end of the lever I,
which is fulcrumed in a bracket I¹ on the top of the frame D, and actuated at its
inner end by the screw spindle J working down through the hollow spindle D¹
actuated at the top by a hand wheel J' by the steersman on deck, so that he can
slack or fix the blades instantaneously by the screwing up or down of the lever I
before and after shifting the blades A, A, to the desired pitch or position, and fix
them all as stated by the holding grooves in the spindle all, and as particularly
seen in Figures 12 and 13 which show the latter, being a plan view of the steering
gear E, E, E, and the hand wheel H', J', for shifting and fixing the propeller
blades A, A, as stated. Other equivalent arrangements of mechanism might be
employed for swivelling the screw blades A, A, of the propeller than those herein
described and shown, such as an oscillating spindle instead of the sliding spindle
or boss a¹¹, B', working on the back end of the propeller shaft C by a scroll or
wedge action made to swivel the screw propeller blades in an equivalent manner
to that described, by the rod or sleeve all, or the groved sliding boss B' on the outside
of the shaft C¹, as has been done in some other arrangements of ordinary feathering
screw propellers which (do not swivel in their carrying frames) merely alter the
pitch, but not for making the screw to propel both in forward and backward direc-
tions. The swivelling screw blades of this new or improved combination of forward
and backward propelling and steering screw propeller may be made of any of the
ordinary constructions and material, as of malleable cast-iron or steel out of the solid,
or built of plates; but preferably the latter, of an increasing pitch or true screw on the
front and forward acting surface to the mean pitch desired to suit the power and
velocity of the engines in relation to the speed of the ships, so that when the blades
have to be increased in pitch, or diminished, the slight nonconformity of the curve
of the surface of the blade will not materially injure the effective working of the
blades in their abnormal positions, and it is preferred to have the blades made with a
less or finer pitch towards the boss B, and to keep them as clear of that as possiblo,
particularly at the lower and outer edges and surfaces to give freedom there for
the escape of the water backwards to prevent the power of the propeller being spent
in churning or swirling the water at the boss, as indicated particularly in Figures
1, 3, and 5. Although only two blades have been described in reference to and
shown in the several modifications on the Sheet of Drawings, this being the most
convenient, yet still it will be seen that three or four blades could be fitted and
actuated in the same manner in accordance with the improvements of this Inven-
tion. For three blades they would be mounted at equal distances round the one boss,
and have a separate eccentric pin a¹ and swivelling arrangement as described for
each blade A; or, for the four blade arrangement, two blades may be mounted on
one side of one swivelling spindle or eye, and two on the other side on a corres-
ponding spindle, the one blade of each in advance of the other, and with their
acting surfaces parallel to each other, some distance apart, as the sectional segment
of a double threaded screw. By another arrangement two sets of opposite screw
blades A, A, might be mounted on axes a, a, on the boss B, at right angles to each.
other, and at a sufficient distance apart as to swivel clear of each other; all other-
wise in both these arrangements of three or four blades, substantially as described,
in reference to the two bladed arrangements shown in the Drawings, and all mounted
on the short screw shaft C, so as to revolve within the open swivelling frame D
carrying the whole, oscillated to any required angle within 90° to port or starboard,
to propel and steer the ship by the screw propeller at the same or slower speeds, and
reverse or back the ship by the person in charge, all without requiring to loose time
in signalling the engineers, or reversing or stopping the steam engines. The journal
bush bearings e and e¹ of the short screw shaft C in the frame D¹ may be formed
with removable screwed on side covers, as shown in Figures 7 and 8, for the conve-
nience of uncoupling the shaft C at its ball joint c, f, and removing and taking it on
deck when requiring repairs, or otherwise, as shown in Figures 1 and 2, the shaft C
may be uncoupled from its socket joint f and drawn back through the bush bearing
eyes e and e¹, and out of its propeller boss B, or along with the boss when the stern

page_text: post D₁ of the frame D is made portable and removable by screw joints for the
convenience of removing and replacing the propeller A, B, and its shaft C.
When desired the levers and rods G, G, and i, I, and their connections on the
frame D may all be enclosed within a strong sheet-iron case secured to the frame D
for protecting them, as shown dotted-in at K in Figures 7 and 8.
It will be seen that this new or improved arrangement of screw propeller could
be fitted at the bow frame or stem of steam ships in an equivalent manner to that
described, and shewn in the Drawings as applied to the stern frame. And also that
twin screws (instead of one only, as shown) could be similarly fitted to ships made
with double keels and stern or bow frames for the purpose, with a water way or
-channel-between-such-frames.This.new-or-improved screw-propeller_we_consider
will be most applicable to, and of the greatest advantage in all steam vessels
requiring the greatest possible universal power of steering, and of instantly con-
trolling the speed of the ship, as for steam ships and launches trading in estuaries
and confined waters, and for ships of war, gun-boats, and torpedo boats.
We do not desire to claim the mère fitting or use of an ordinary fixed bladed
screw propeller in a rudder swivelling construction of open frame, as this has beforō
been done, except in connection with our new or improved combination or mode
and means of applying feathering screw propellers to such swivelling frames, and
controlling the action thereof for the better steering or manoeuvring of steam ships.
Having now described the nature of our said Invention, and the manner of per-
forming the same, we have to state that we do not confine ourselves to the
precise details herein described or delineated, but what we consider to be novel
and original, and therefore claim as the Invention secured to us by the herein-
before in part recited Letters Patent is,―
First. The general arrangement and combination of the parts of a screw propeller
A, B, C, in a rudder like swivelling frame D, and fittings or gear for swivelling said
frame D, and also for feathering the screw blades A, A, for the purpose of propelling
the ship forwards or backwards at full speed, or any slower speed, or stop its motion;
all without the necessity of stopping or interfering with the motion or reversing of
the steam engines, all substantially as herein described in reference to and sliown in
the accompanying Drawings, or any mére modification thereof,
Second. The fitting a feathering screw propeller to a rudder swivelling construc-
tion of open frame, and carrying its controlling gear up through the hollow spindle
of the said frame, so as to easily set and fix the blades to the desired angle on board,
or by the person attending to the steering of the ship by the said swivelling pro-
peller frame, all substantially as herein described in reference to and shown in the
accompanying Drawings, or any mere modification thereof.
Third. The general arrangement of mechanism for swivelling the blades of
feathering screw propellers carried in a rudder swivelling construction of open framo
for the propelling and steering of steam ships or vessels, all substantially as herein-
described in reference to and shown in the accompanying Drawings, or any meré
modification tliereof.
Fourth. The construction and use of single_or_double_ball_and_socket_universal
joints for coupling the outer shaft of screw propellers mounted on swivelling frames
to their internal main driving shaft, all substantially as herein described in reference
to and shown in the accompanying Drawings, or any mere modification thereof.
In witness whereof, I, the said John Lorimer Corbett, on behalf of the said
William Young Fleming and myself, have hereunto set my hand and seal,
this Sixth day of August, in the year of our Lord One thousand eight hun-
dred and seventy nine.