IMPROVEMENTS IN SCREW PROPELLERS
Year: 1876

page_text: LETTERS PATENT to Samuel Luke, of Chelsea, in the County of Middlesex, and
Charles James Southgate, of Mill Road, Bexley Heath, in the County of
Kent, Mechanical Engineers, for the Invention of "IMPROVEMENTS IN SCREW
PROPELLERS."
Scaled the 11th August 1876, and dated the 9th May 1876.
PROVISIONAL SPECIFICATION. left by the said Samuel Luke and Charles
James Southgato at the Office of the Commissioners of Patents on the 9th May
1876.
SAMUEL LUKE, of Chelsea, in the County of Middlesex, and CHARLES JAMES
SOUTHGATE, of Mill Road, Bexley Heath, in the County of Kent, Mechanical
Engineers. "IMPROVEMENTS IN SCREW PROPELLERS."
The features of novelty in this Invention consist in adapting to the ordinary
blades of a screw propeller auxiliary blades of steel, iron, or other inetal, they are
fixed to or near the outer ends of the propeller blades by screws, bolts, rivets, or
otherwise, in such manner that their ends furthest from the points of junction
extend towards and reach beyond the boss of the propeller, the metal of which
they are formed gradually diminishes in thickness and width as it reaches the
extremities or freo ends, this gives them a certain springy elasticity, and they aro
connected to the propeller blades inversely ono with the other, their pitch or
curvature, which is a gradually increasing one, would together with their position
bo regulated to suit the propeller and vessel to which they are to be applied.
The object of these improvements is to prevent the slip and racing of the screw,
so common with the ordinary screw propellers, and is the frequent cause of breakage
of the screw blades and propeller. The thickness and form of the blades would
vary to suit the vessel to which they are applied. These additional blades can be
fixed to existing propellers or cast on new ones, or they may be connected to the
propeller shaft by a separate boss.
By the employment of propellers constructed on this principle an increase of
propelling power is attained with a decrease in the diameter of the screw.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Samuel Luke and Charles James Southgate in the Great Seal Patent
Office on the 2nd November 1876.
SAMUEL LUKE, of Chelsea, in the County of Middlesex, and CHARLES JAMES
SOUTHGATE, of Mill Road, Bexley Heath, in the County of Kent, Mechanical
Engineers. "IMPROVEMENTS IN SCREW PROPELLERS."
It is an acknowledged fact that the ordinary screw propellers as at present
employed have a tendency to slip or race, or in other words that they do not on
first starting grip the water, but revolve without, at once effecting any appreciable
effect on the vessel's forward or backward motion as the case may be.
With the view of remedying these defects and at the same time rendering the
ship instantly obedient to the helm, we adapt to the ordinary blades of a screw
propeller auxilliary blades of steel, iron, or other metal, these additional blades are
attached to the propeller blades by means of bolts, screws, or somo equivalent
connection, in an inverse sense one with the other, they are fixed to or near the
outer ends of the propeller blades in such manner that their ends farthest from the
points of junction extend towards and reach beyond the buss of the propeller,
the metal of which they are formed gradually diminishing in thickness and
gradually tapering in form as it reaches the extremities or free ends, this imparts
to them a certain amount of springy elasticity, and their pitch or curvature, which
is a gradually increasing one, would together with their position, thickness, and
form, be regulated to suit the propeller and vessel to which they are to be applied.
These additional blades can be fixed to existing screw propellers or cast or other-
wise fixed on new ones, or they may be connected to the propeller shaft on a
separate boss.
By the employment of screw propellers constructed on this principle an increase
of propelling power is obtained with a decrease of the diameter of the screw.
These additional blades take a firm grip as soon as set in motion, causing the
instant motion of the vessel either forwards or backwards as required, and have
such a command over the vessel that it can be stopped in its own length and
turned in a much less space than by ordinary screw propellers.
Figs. 1 and 2 represent a plan and end view of a screw propeller having our
additional blades a, a, fixed or connected to the ordinary blades by any convenient
means.
Having thus described our Invention and the method of carrying the same into
effect, what we claim and desire to secure by Letters Patent is, the adaptation of
the auxilliary blades a to the ordinary screw propeller, in the manner, by the means,
and for the purposes precisely as herein set forth.
In witness whereof, we, the said Samuel Luke and Charles James Southgate,
have hereunto set our hands and seals, this First day of November, in the
year of our Lord One thousand eight hundred and seventy-six.
SAMUEL LUKE.
(L.S.)
Witness,
A. C. HENDERSON,
6, Southampton Buildings,
Holborn.
CHARLES JAMES SOUTHGATE. (L.S.)