AN IM- PROVEMENT IN SCREW PROPELLERS
Year: 1878

page_text: LETTERS PATENT to Farnham Maxwell Lyte, of the Scientific Club, Saville
Row, in the County of Middlesex, Esquire, for the Invention of "AN IM-
PROVEMENT IN SCREW PROPELLERS."
Sealed the 25th February 1879, and dated the 29th August 1878.
PROVISIONAL SPECIFICATION left by the said Farnham Maxwell Lyte at
the Office of the Commissioners of Patents on the 29th August 1878.
FARNHAM MAXWELL LYTE, of the Scientific Club, Saville Row, in the County
of Middlesex, Esquire. "AN IMPROVEMENT IN SCREW PROPELLERS."
This Invention relates to an improvement in screw propellers whereby the
maximum of strength and durability with the minimum of friction and fouling are
obtained.
It is a well-known fact that one great cause of imperfection in screw propellers
for ships is the difficulty of finding a suitable metal for their construction. It is
obvious that the stronger the metal the thinner the blades of the screw can be
made, and, consequently, the less will its revolutions be hindered by friction, while
the boss can be made of smaller diameter and will encounter less resistance to its
passage through the water.
The screws of. merchant ships are usually made of cast or wrought iron, and
become speedily roughened and eaten into holes by rust, and often become weakened
and even break from this cause. They are also liable to become fouled by marine
growth.
In view of these facts the British Admiralty have adopted' gun-metal screws
throughout the Navy, and these have sometimes been used in some of the best
merchant ships.
In point of strength gun metal is but a poor substitute for steel or even iron.
Screws made of it require to be far more heavily constructed than those of iron or

page_text: steel, and the frictional effects above mentioned are necessarily far greater than
would be the case with a new and clean iron or steel screw propeller, besides which
the cost is so high as in many cases to be absolutely considered prohibitory.
With a view then to combine the advantages of lightness and strength as well
as to prevent fouling, to maintain smoothness of surface, and to prevent oxidation,
I propose to construct screw propellers of steel, wrought or cast iron, and to protect
their surfaces by means of an adherent deposit of copper, nickel, or such other
metals or alloys suitable for the purpose as can be electrically deposited on iron or
steel.
The most convenient method of which I am at present aware for producing such
an adherent film on iron or steel is that described in the Specifications of Patents
Nos. 3136, 1873, and 3392, 1878.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Farnham Maxwell Lyte in the Great Seal Patent Office on the
27th February 1879.
FARNHAM MAXWELL LYTE, of the Scientific Club, Saville Row, in the County
of Middlesex, Esquire. "AN IMPROVEMENT IN SCREW PROPELLERS."
This Invention relates to an improvement in screw propellers whereby the
maximum of strength and durability with the minimum of friction and fouling are
obtained.
It is a well-known fact that one great cause of imperfection in screw propellers
for ships is the difficulty of finding a suitable metal for their construction. It is
obvious that the stronger the metal the thinner the blades of the screw can be
made, and, consequently, the less will its revolutions be hindered by friction, while
the boss can be made of smaller diameter and will encounter less resistance to its
passage through the water.
The screws of merchant ships are usually made of cast or wrought iron, and
become speedily roughened and eaten into holes by rust, and often become weakened
and even break from this cause. They are also liable to become fouled by marine
growth.
In view of these facts the British Admiralty have adopted gun-metal screws
throughout the Navy, and these have sometimes been used in some of the best
merchant ships.
In point of strength gun metal is but a poor substitute for steel or even iron.
Screws made of it require to be far more heavily constructed than those of iron or
steel, and the frictional effects above mentioned are necessarily far greater than
would be the case with a new and clean iron or steel screw propeller, besides which
the cost is so high as in many cases to be absolutely considered prohibitory.
With the view then to combine the advantages of lightness and strength, as well
as to prevent fouling, to maintain smoothness of surface, and to prevent oxidation,
I propose to construct screw propellers of steel, wrought or cast iron, and to protect
their surfaces by means of an adherent deposit of copper, nickel, or such other
metals or alloys suitable for the purpose as can be electrically deposited on iron or
steel.
A convenient method for producing such an adherent film on iron or steel is by
using one of the known processes of electro-plating iron with copper, and the best
results are arrived at by the use of the ammoniacal cyanide copper bath for
covering the screw, properly cleaned, with an adherent film of copper, and sub.
sequently thickening this said adherent film by further deposition in the ordinary
sulphate of copper bath. A screw propeller is thus produced composed of steel
or iron interiorly for strength, and copper exteriorly for the purposes above
already mentioned.
Having described the nature of my Invention, and the manner of performing the
eame, I declare that what I claim as my Invention, to be protected by the herein-
before in part recited Letters Patent is, the construction and employment of screw
propellers for ships of steel or iron coated with an electrically deposited adhesive film
of copper, as and for the purpose specified.
In witness whereof, I, the said Farnham Maxwell Lyte, have hereunto set
my hand and seal, this 25th day of February, in the year of our Lord One
thousand eight hundred and seventy-nine.
F. MAXWELL LYTE. (L.S.)