IMPROVEMENTS IN PROPELLERS FOR PROPELLING VESSELS, AND IN THE CONSTRUCTION OF VESSELS TO WHICH PROPELLERS ARE APPLIED
Year: 1877

page_text: 'LETTERS PATENT to Matthew Piers Watt Boulton, of Tew Park, Oxfordshire,
Esquire, for the Invention of "IMPROVEMENTS IN PROPELLERS FOR PROPELLING
VESSELS, AND IN THE CONSTRUCTION OF VESSELS TO WHICH PROPELLERS ARE
APPLIED."
Sealed the 8th September 1877, and dated the 5th July 1877:
PROVISIONAL SPECIFICATION left by the said Matthew Piers Watt Boulton
at the Office of the Commissioners of Patents on the 5th July 1877..
MATTHEW PIERS WATT BOULTON, of Tew Park, Oxfordshire; Esquire. "
" IMPROVE-
MENTS IN PROPELLERS FOR PROPELLING VESSELS, AND IN THE CONSTRUCTION OF
VESSELS TO WHICH PROPELLERS ARE APPLIED."
This Invention relates to improvements in propellers for propelling vessels, and in
the construction of vessels to which propellers are applied.
In propellers constructed according to this Invention the propulsive agency is
produced by means of fluid friction, this friction being produced by means of cells
or chambers in the propeller open to the outer water.
One form of propeller constructed according to this Invention consists of a trough
For vessel fitted with numerous cells or chambers, which trough or vessel is caused to
move backwards and forwards by a rectilinear movement behind an aperture
provided in the side of the vessel under the water. The mouths of the cells or
chambers are in contact with the outer water, but the ends of the propeller move
within the vessel and not through water.
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:
The propeller works water-tight behind the aperture, so that the outer water
cannot enter the ship or vessel propelled through the aperture, but the outer water
can enter the cells or chambers within the propeller previously mentioned, which
therefore are filled with water.
The object of the cells or chambers above described is to generate fluid friction
when the apparatus is caused to move while the mouths of the chambers above
1

page_text: described are open. The cells or chambers may therefore have any shape suitable
for the generation of fluid friction, which shape may be very various.
Apparatus is provided by means of which communication between the cells above
mentioned and the outer water can be opened or closed, which may be done in
various ways.
The action of this apparatus is so timed that when the propeller makes
its stroke in one direction the cells are opened to the outer water, while when it
makes its stroke in the reverse direction they are closed.
When the stroke of the propeller is made with the cells open, fluid friction or
agitation of the water is created in consequence of the action between the outer
water and the water within the cells. This causes resistance to the backward
movement of the propeller, and in consequence of this a pressure is created urging
the vessel forward, this pressure being the propulsive agency employed.
When the propeller makes its return stroke, during which the cells are closed, the
fluid friction or agitation of water above described is not created, and in con-
sequence the stroke is made with little resistance.
When it is desired to reverse the direction of propulsion, the action of the apparatus
for opening and closing communication between the cells and outer water is
differently timed, so that this communication is opened in the stroke during which
it was previously closed, and vice versa. In consequence of this the propulsive
agency is exerted in the reverse direction.
Propellers constructed as above-described may work upon the outer sides of a
vessel. Or they may work upon the sides of a central channel running through the
vessel, having the nature of a hollow keel, one propeller working on each side of
the channel.
They may also be arranged so as to work on three sides of a central channel or
hollow keel, two on its two vertical sides and one on its upper side.
The movements of the propellers may be timed so that propulsive agency is
always exerted on the vessel.
If the vessel is a twin ship then the propellers may work upon the sides of the
central channel, one on each side of it, and this is a convenient position for
them.
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The principle of action above described is also applicable to helical propellers. I
proceed to describe a construction of helical propeller acting on this principle. I
arrange on a core a helical chamber or hollow body winding helically round the
core. Accordingly two sides of this chamber are formed by helical surfaces or screw
threads, one in front of the other.
The whole apparatus above described works under the water, having its longitu-
dinal axis parallel to the longitudinal axis of the vessel.
The ends of the core and helical chamber are fitted with tapering bodies shaped
so as to diminish resistance from motion through the water.
The interior of the helical chamber is fitted with cells or chambers, the object of
these being to generate fluid friction or agitation of water in the manner described
above.
The helical surfaces above described are provided with apertures through which
the outer water can enter the cells within the helical chamber. These apertures are
provided with doors or valves so connected or arranged that when the valves close
the apertures on one of the helical surfaces they open them on the other. This
opening and closing of the valves may be effected by the pressure of the water
produced by the working of the instrument.
The action is as follows: When the propeller works in one direction the pressure
. of the water on the hinder or driving helical surface opens the valves which control
the apertures on that surface, while they close the valves which control those on the
opposite helical surface. Thus fluid friction is created by the action of the driving
helical surface, while it is not so created by the opposite one.
The fluid friction created as above described causes resistance to the movement of
the driving helical surface, and in such a way that a pressure is produced urging

page_text: the vessel to advance in the same way on which it would advance if the helical
thread were working against a solid thread.
When the direction of the propeller's rotation is reversed, the valves are closed on
the surface on which they were previously open, and vice versa, and thus an action
is produced similar to that previously described, but urging the vessel in the
opposite direction.
I prefer to place the helical propeller thus constructed within a channel which at
bottom is freely open to the outer water and communicates with it fore and aft by
easily curved channels, arranged or shaped so that the water enters and leaves them
with little resistance. These channels are arranged so that a portion of the shaft
attached to the propeller works within the vessel, this portion being connected with
the engine or engines which work the propeller.
It is convenient to employ two channels, one fore and one aft, the space wherein
the shaft is connected with the engine power being central and between these.
Such a construction is a modified form of twin vessel.
The construction of passages and of vessels above described remains suitable when
a different mode of propulsive action is employed.
The shaft being placed and working, as above described, may carry on it numerous
helical propellers of ordinary form, placed in line one behind the other and separated
by intervals.