IMPROVEMENTS IN SCREW PROPELLORS
Year: 1881

page_text: LETTERS PATENT to Captain George Peacock, F.R.G.S., of Regent House,
Starcross, in the County of Devon, for an Invention of " IMPROVEMENTS IN
SCREW PROPELLORS."
PROVISIONAL SPECIFICATION left by the said Captain George Peacock
at the Office of the Commissioners of Patents on the 28th May 1881.
Captain GEORGE PEACOCK, F.R.G.S., of Regent House, Starcross, in the County
of Devon. "IMPROVEMENTS IN SCREW PROPELLORS."
This Invention has for its object improvements in screw propellors.
My improved screw propellor has a conical boss, and the apex is next the stern
post. The blades (which may be two or more in number) as they recede from the
boss incline forward. Their form is such that a plane dividing the shaft longi-
tudinally will cut the face of the blade in a curve which is a cycloid; for this
reason I call my propellor a cycloidal propellor. The face of the blade where it
meets the boss is inclined to the shaft at an angle of about 45 degrees. At the
periphory the inclination to the shaft is about 20 degrees.
The Drawings annexed represent my propellor seen from different points of view.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Captain George Peacock in the Great Seal Patent Office on the
26th November 1881.
Captain GEORGE PEACOCK, F.R.G.S., of Regent House, Starcross, in the County
of Devon. "IMPROVEMENTS IN SCREW PROPELLERS."
This Invention has for its object improvements in screw propellers.
My improved screw propeller has a conical boss, and the apex is next the stern
post. The blades (which may be two or more in number) as they recede from the
boss incline forward. Their form is such that a plane dividing the shaft longi-
tudinally will cut the face of the blade in a curve which is a cycloid; for this reason
I call my propeller a cycloidal propeller. The face of the blade where it meets the
boss is inclined to the shaft at an angle of or about 45 degrees. At the periphery
the inclination to the shaft is about 20 degrees, terminating in a lip.
If desirable not to cast the propeller whole, the blades may be separately attached
to the boss with stout flanges and strong screw bolts, so that in the event of fracture
the broken blade can be readily detached, and a spare blade fitted; these flanges
will be cast to the exact angle of attachment to the boss, and for better security to
prevent slipping fillets may be cast on the boss at the back of each blade, and
these fillets inay be made to extend outwards towards the centre of the blade at
its back to give support to the blade in its progressive motion; to prevent the
possibility of the screw bolts moving check nuts or stop plates may be used if
required, and rim cast on the boss along the line of seating for the flange at the
front or after part of the propeller, as well as at the back, so as to make the whole
perfectly secure.
The Drawings annexed represent my propeller seen from different points of view.
What I claim is my improved screw propeller, substantially as described.
In witness whereof, I, the said Captain George Peacock, have hercunto set
my hand and seal, this Twenty first day of November, in the year of our
Lord One thousand eight hundred and eighty-one.
ARA
DR LOOK