IMPROVEMENTS IN AND CONNECTED WITH SCREW PROPELLERS
Year: 1876

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lanc, in the
County of Middlesex, Patent Agent, for the Invention of "IMPROVEMENTS IN
AND CONNECTED WITH SCREW PROPELLERS." A communication from abroad by
John Ellis, of Freeport, in the County of Queens, and State of New York,
United States of America.
Sealed the 3rd March 1870, and dated the 12th January 1876.
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark at the
Office of the Commissioners of Patents, on the 12th January 1870,
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN AND CONNECTED WITH SCREW PROPELLERS."
A communication to me from abroad by John Ellis, of Freeport, in the County of
Queens, and State of New York, United States of America.
This Invention consists of a long tapering propeller, with the small end forward,
the blades being of continuous differential pitch and differential diameter, thereby
causing increasing pressure upon the water the entire length of the propeller, and
also reaching out and taking hold the entire length farther into the water.
The Invention also consists of the propeller located in a channel extending from
the termination of the main keel a little aft of the commencement of the run
of the ship to the stern post, the channel being formed by two parallel keels
extending from a point a little forward of the main keel to the stern post, a
clear passage for the water being left between the main and parallel keels.
The
shaft of the propeller passes through the main keel at or near its termination into
the hold of the ship, and does not interfere with the carrying capacity.
Referring to the acompanying Drawing, Figure 1 is a longitudinal sectional
elevation of a ship with a screw propeller arranged according to this Invention ;
Figure 2 is a plan of the bottom of the ship; and Figure 3 is a transverse
section taken on the line X, X. Similar letters of reference indicate corresponding
parts.
A is the long tapering propeller, having continuous blades of increasing pitch and
diameter arranged in the channel B, between the two parallel keels C behind the
main keel D, through which the shaft E of the screw passes into the hold of the
ship, the said main keel terminating a little aft of the commencement of the run,
as shown, and the keels C, beginning a little forward of such termination with free
[Price 4d.l

page_text: openings for water into the propeller channel at F. G is a bridge at the rear
end of the channel, in which the propeller shaft is supported, but the bearing can
be attached to the stern post, said stern post extending to the bottom of the
channel, but the arrangement shown is less liable to damage, as the strain on the
stern post, which also has to carry the rudder, would be too severe. The position
of the rudder ensures its safety by protection from anything floating in the water,
also from shot, and being always under water the engine will not race when the
ship pitches. The form and position of the propeller also give increased speed to
the ship.
Having described the nature of the Invention, and the manner of performing
the same, I declare that what I claim as new, and desire to secure by Letters Patent
is,-
1st. The tapering propeller having continuous blades with increasing diameter
and pitch from front to rear, substantially as specified.
2nd. The said tapering propeller arranged in a channel formed by two parallel
keels C, and beginning at the termination of the main keel, a little aft of the com-
mencement of the ship's run, substantially as specified.
3rd. The propeller shaft extending through the main keel into the hull of the
ship at the rear termination of the keel, substantially as specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twelfth day of January, in the year of our Lord One
thousand eight hundred and seventy-six.
A. M. CLARK. (L.D.)