AN IMPROVED PROPELLING APPARATUS
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by William Lloyd Wise at the
Office of the Commissioners of Patents, with his Petition, on the
11th March 1875.-A communication from abroad by Mons'. Jean
Henry Bertot, of Paris, France, Engineer.
I, WILLIAM LLOYD WISE, of Chandos Chambers, Adelphi, in the
County of Middlesex, do hereby declare the nature of the said Invention
for "AN IMPROVED PROPELLING APPARATUS," (a communication to me from
abroad by Mons. Jean Henry Bertot, of Paris, France, Engineer,) to be
as follows:-
This Invention has for its object an improved propelling apparatus.
In communicating this Invention to me my foreign correspondent says
"I give the name of 'refouleur' to the propelling apparatus which is the
subject of this Specification. I chose this name because of the mode of
working of this propelling apparatus, which in its normal condition of
motion tends to drive back (refouler) the particles of water in contact
with it, each particle in a constant direction, and all with a common and
uniform speed, on the hypothesis that these particles considered as
independent of one another move like free and isolated particles, all
friction and reaction being left out of consideration.

page_text: This apparatus is intended to act under the conditions of a screw
propeller, that is to say, that it should be mounted on a horizontal shaft
placed in the longitudinal plane of the vessel, or parallel to that plane.
if it is employed as a twin apparatus. It can work at the stern of a ship
instead of a screw,
and in the same place also in a central channel or
interior canal inside the vessel, taking the water from the front and
throwing it out behind along the sides of the hull through openings
placed for that purpose in the same manner as the gills of a fish. I
specially include this last arrangement which is designed to catch in the
canal a portion of the water which the vessel would divide in its
progress, in order during and after the action of the refouleur to replace
it behind in the vacuum which the vessel tends to leave in the wake of
its midship section. I equally include in this application the employ-
ment which can be mado of this "refouleur," as the main part of an
apparatus either for ventilation or for pumping.
The refouleur is analogous as a whole to the screw propeller like it, it
is composed of blades carried on a nave, but it differs from it essentially
in the nature of the surface of its blades. This surface is derived from
that of the helicoid with a plane directrix following the rule which is
hereafter pointed out.
Suppose a screw propeller of the archimedean type with a constant
thread (pas) mounted on its shaft in place on board the vessel.
The vessel and its screw are supposed motionless at rest. The blades
are supposed to be without thickness and reduced to the simple
geometrical surface of the helicoid under consideration.
At each point (M) of the surface of the blade of the screw conceive
first the right cylinder with a circular base concentric with the screw
and passing through the point (M), then the plane tangent to this
cylinder at the same point (M). In this plane we draw through the
point (M) a straight line (M, N,) making an angle (a) with the a
generatrix of the cylinder contained in the tangent planc.
Considering in this plane the point (M) as the pole of a system of
polar co-ordinates, of which the arc would be the part of this generatrix
directed from the point (M) towards the bow of the ship, the angle (a)
is the angular co-ordinate of the different points of the line (M, N,) ;
passing through the point (M) considered co-ordinate according to
custom.

page_text: In WHICH
1°. 2 R is the length of the circumference of the circle described
by the point (M) in the rotation of the screw round its own axis, and R
the radius of that circle or the distance of the point M from the axis of
the screw.
2. His the thread (pas) of the screw.
3°. O is an arbitrary constant representing the speed of the driving
back for one turn of the shaft, and the valve of which will be chosen
according to the circumstances and conditions of the propulsion.
From the point (M) along the straight line (M, N,) we will cut off a
length (M, N,) which will be a fraction of the straight line, the length
of which is equal to the constant C, this fraction being equal to that of
the thread (pas) of the screw included between the generatrix of the
helicoid passing the point (M) and the generatrix of the same surface
forming the forward edge of the blade of the screw and taken as the line
from which it originates.
The geometrical locus of the points (N) thus obtained, corresponding
to cach of the points (M) of the original liclicoid, is the surfaco which I
propose to substitute for that employed in the construction of the screw
propeller.
It is to be remarked that the straight line (M, N,) is normal to the
new surface thus derived from that of the screw; hence results, inter
alia, a means of constructing this surface which can be set off point by
point, as is about to be shown from a block of material in order to
construct a model. Let us conceive that we have beforehand cut off a
part of the surface of this block along a helicoid with a plane directrix
or surface of an archimedean screw; let us suppose that we have
drawn on this part of the surface of the block a generatrix of the
helicoid, the plane passing through this generatrix parallel to the plano
directrix, or what comes to the same thing, perpendicularly to the axis
of the helicoid, will be considered as the common plane of origin of the
helicoid and of tho surface to be obtained, from which will be reckoned
the thread (pas) of the helicoid and its fractions.
At different points of the helicoid and in each of those according a
direction determined by the corresponding value of the angle (a) defined

page_text: above, let us suppose that we cause an auger or a drill to penetrato into
the mass to a depth equal to the corresponding value of (M, 'N,) for eaclí
of tlicse points.
By increasing the number of these penetrations and making them
approach nearer and nearer together, we shall at last obtain by this 5
method of arriving at the end as many points as we wish of the required
surface, points which we shall unite together with greater exactitude,
according as we increase the number of them, and thus mako them
approach nearer to each other: