IMPROVEMENTS IN ROTARY PPOPELLERS AND APPARATUS FOR CREATING FLUID CURRENTS
Year: 1880

page_text: LETTERS PATENT to Matthew Piers Watt Boulton, of Tew Park, in the
"
County of Oxford, for an Invention of IMPROVEMENTS IN ROTARY
PPOPELLERS AND APPARATUS FOR CREATING FLUID CURRENTS."
"
PROVISIONAL SPECIFICATION left by the said Matthew Piers Watt
Boulton at the Office of the Commissioners of Patents on the 15th December
1880.
MATTHEW PIERS WATT BOULTON, of Tew Park, in the County of Oxford.
IMPROVEMENTS IN ROTARY PROPELLERS AND APPARATUS FOR CREATING FLUID
CURRENTS."
".
This Invention relates to rotary propellers and apparatus for creating currents of
fluids, such as water, air, or gas.
In the following description I shall first describe my improved construction of
propeller, which I shall suppose to be mounted in the usual way at the stern of a
vessel. The object aimed at is principally to discharge the stream created by the
propeller in a direction contrary to that of the vessel's movement, or more nearly in
that direction than is done by an ordinary screw propeller.
For this purpose I enclose the propeller within a casing or passage having the
form of a surface of revolution round the axis of the propeller. This easing may be
stationary, the blades revolving within it, or it may be attached to the blades and
revolve along with them. In the latter case, besides the arms which connect the
casing to the axis, and which may be formed to act as blades, additional inter-
mediate blades may be attached to the casing, and these may be supported on the
interior by a ring or rings. The casing in its longitudinal section is of curved or
barrel form, being larger in its middle and smaller at its two mouths. For
convenience of reversal I prefer to make its curvature symmetrical, and the blades
are placed in it symmetrically. They may be of helical or helicoidal form, or they

page_text: may be flat blades inclined to the axis; in either case they impart two movements
to the water, one parallel to the axis and one vortical.
I consider that when a propeller works within a curved casing, such as I have
described, the water at the middle part of its course through the apparatus has
more vortical movement and slower flow parallel to the axis, and at the mouth of
out flow where it quits the casing has less vortical movement and quicker flow
parallel to the axis, and this is the condition which I desire by the construction to
produce.
Instead of enclosing the propeller within an entire casing, as above described,
each blade might have attached to it a portion of such a casing, sufficient to direct
the water in the direction desired.
I prefer to make the blade as well as the casing symmetrical on each side of the
middle line, so that the apparatus is equally well fitted to propel the vessel
either fore or aft, the reversal of movement being effected by reversing the direction
of rotation.
Apparatus constructed like those above described may be employed to impart
movement to water or air or generally to fluids. When the apparatus is used for this
purpose, I consider it well to employ on the outflow side a guiding interior surface,
between the outer casing and the axis so as to form a passage with contracted
mouth through which the outflowing current passes. Beyond such contracted
mouth an annular tapering passage expanding towards the outflow may be provided.