IMPROVED MEANS OF INCREASING THE MOTIVE EFFECT OF SCREW PROPELLERS, AND OF DIMINISHING RESISTANCE TO MOTION IN VESSELS PROPELLED
Year: 1855

page_text: application for Letters Patent was not given within the time prescribed
by the Act.)
PROVISIONAL, SPECIFICATION left by Richard Howson at the Office of
the Commissioners of Patents, with his Petition, on the 19th March
1855.
I, RICHARD HOWSON, of Lancaster, Engineer, do hereby declare the nature
of the said Invention for "IMPROVED MEANS OF INCREASING THE MOTIVE EFFECT
OF SCREW PROPELLERS, AND OF DIMINISHING RESISTANCE TO MOTION IN VESSELS
PROPELLED," to be as follows:-
It consists in certain new adaptions of form.; firstly, in screw propellers;
secondly, in the entrance or bow lines of ordinary sea-going vessels; and,
thirdly, in a series of vessels to be attached together in a chain for navigating
on cauals; these several adaptions of form being principally directed towards
one object, namely, the obtaining of a higher speed than has hitherto been
arrived at in screw navigation generally. The improved form of screw pro-
peller may be thus described :-If a section of the blade be taken (at any part)
at right angles to the axis, the acting line for forward motion will have the
following shape it will first spring from the boss at a tangent to it, and from
this will bend backwards with a continually expanding curve until it reaches
not less than two-thirds of the entire radius; it will then commence to turn
in the contrary or forward direction, and will continue to do so with a rapidly
contracting curve until it terminates at right angles, or nearly so, with the

page_text: radius. The form of screw thus produced offers small resistance to the water
laterally, but has powerful axial effect.
The improved shape of entrance or bow lines is such, that if a cross section
of the vessel be taken at any part between the stem and the midship section,
the lines bounding the submerged portion will consist for the most part of
vertical lines cutting horizontal lines at right angles, or of vertical lines
cutting the lines of midship section, the angles of intersection in both cases
being merely rounded off. The resulting form is such as to confine the
resistance which the vessel encounters when in forward motion almost entirely
to lateral resistance; the resistance to vertical pressure, or that which gives
the vessel a tendency to rise, being reduced to as small a quantity as possible.
The improvement in the shapes of vessels to navigate on canals is for the
purpose of enabling a series of them attached together to be propelled
through the water with as small an amount of resistance as possible. It is as
follows: I make the first boat with a sharp bow, but with a semicircular
concavity at the stern, and the second boat I make with a convex bow to fit
the aforesaid stern; I now continue a series of beats with convex bows and
concave sterns, so as to be capable of being jointed together successively to any
number, but the last boat I prefer to have a sharp stern. It will thus be seen
that a long and flexible chain of boats may be constructed, which offers little
more resistance to the fluid through which it passes than does a single boat of
the ordinary shape. In order to propel this chain of boats I place the screw
in advance of the stern of the first boat: