Improvements in Preventing or Partly Preventing the Pitting or the Deterioration of Screw-propellers and Propeller-shafts for Steam Ships.
Year: 1886

page_text: PROVISIONAL SPECIFICATION.
Improvements in Preventing or Partly Preventing the Pitting or
the Deterioration of Screw-propellers and Propeller-shafts for
Steam Ships.
I MATTHEW PRIOR, of 3 Cawley Road, South Hackney, in the County of Middlesex,
Engineer do hereby declare the nature of this invention to be as follows:-
In the construction of new propellers one or more wires, rods, or strips of copper,
or of any other suitable kind of good conductors of electricity, are embedded in the
material of which the propeller blades are made by the material being cast around
them. Such wires, rods, or strips, may be placed lengthwise of the blades of the
propeller or crosswise of the same, but by preference I place them lengthwise, and they
inay extend to the full length or breadth of the blades, or to any part of the full length
or breadth of the same. The wires, rods, or strips, may be made plain, but by
preference I make them with nipples which come to the surface of the one side or to
both sides of the blade or blades of the screw propeller. The wires, rods, or strips,
are placed one at any convenient distance from the edge of each blade encircling, or
partly encircling the same; and one or more wires, rods, or strips, of any convenient
form within the space bounded by the outer wire, rod, or strip, and each of them may
be either curved to the shape of the blade or made zig-zag, curvilinear, or concentric
with the outer edge of each blade; or they may be made straight. They may, or may
not be joined or come in contact with each other at the apex or at any other part or
parts of each blade, but by preference I join them or bring them (the wires, rods, or
strips) in contact at the apex, or near to the apex of each blade. I do not confine
myself to any section or thickness of the wires, rods, or strips, as they may, in all
cases, be modified to the various circumstances requiring them. Where it is not
convenient, or not required, to embed the wires, rods, or strips, in the material of
which the screw-propellers are made by the material being cast around them (as
stated in the previous modification) I place the said wires, rods, or strips, with or
without nipples, on the outside of the blades of the screw-propellers, either in grooves
cast in or cut into the blades to receive the same; or I place them on the surface of
the blades, and in either case I fasten them to the blades by means of rivets, bolts, or

page_text: pins, or other suitable means, such rivets, bolts, or pins, being made of any suitable
material, but by preference I make them of copper. I do not confine myself to either
side of the blades of the screw-propeller, as the wires, rods, or strips, may be placed
on either side or on both sides of the blades. Neither do I confine myself to having
in all cases wires, rods, or strips, as the rivets, bolts, or pins, or other like suitable
fastenings, may be placed in the blades of the screw-propellers without wires, rods, or
strips, in the same, or a similar manner as before stated when wires, rods, or strips,
are used.
I also place between one or more of the joints or couplings of the propeller-shaft a
simple disc, or discs, of any kind of material which is a bad conductor of electricity;
and I insulate the bolts which are used to fasten or bind the said joints or couplings
of the screw-propeller shaft together. The discs may be made of any convenient size
or shape, and the ends of the shaft or coupling may be recessed to receive the same,
and the bolts may be insulated their whole length, or only where they come in contact
with the flanges of the joints or couplings of the screw propeller-shaft; and I place one
or more springs, combs, or brushes, or other collectors of electricity, in contact with
the coupling or shaft, or with both; such collectors, or collector, being connected to
insulated conductors to convey any electricity clear of the ship or to be stored for any
useful purpose.
I do not confine myself to any kind of material for the afore said
discs, and insulators for the bolts, but by preference I use ebonite, vulcanite, paper, or
other bad conductor of electricity.
Or I use two or more compound discs in one, or more of the joints or couplings of
the propeller-shaft; one disc made of any kind of material which is a bad conductor
of electricity, and the other disc made of any kind of material which is a good conductor
of electricity, and so placed that one flange of any joint or coupling of the propeller
shaft is in contact with the bad conducting material, and the other flange in contact
with the good conducting material. In this modification of the invention I make the
good conducting discs of any convenient size or shape, but by preference I make them
of a larger diameter than the flanges of the joints or couplings of the Propeller-shaft
and the part of the disc which projects beyond the flanges of the joints or couplings
may be straight, fluted, or bent into any convenient form for the better collecting any
electricity that may be contained therein, and to facilitate its conveyance clear of the
ship, or to be stored for any useful purpose. Although I do not confine myself to
any joint or coupling of the propeller-shaft, as each, or any, or all, of the joints or
couplings may have the above named simple, or compound, discs applied to them, but
by preference, where more than one disc is used, I place at least one simple or com-
pound disc as above named between the flanges of the joint or coupling in the Propeller,
shaft near to the Propeller, and a simple disc of good conducting material on the
opposite end of the shaft near to the engines.
Each of the modifications of this invention may be used separately or the whole
of them may be used collectively in any ship, or for any one propeller, or any
combinations of these modifications of this invention may be used.
Dated 2nd day of December 1886.

page_text: COMPLETE SPECIFICATION.
Improvements in Preventing or Partly Preventing the Pitting or
the Deterioration of Screw-propellers and Propeller Shafts for
Steam Ships.
I MATTHEW PRIOR of 3 Cawley Road, South Hackney in the County of Middlesex
Engineer do hereby declare the nature of my invention for IMPROVEMENTS IN
PREVENTING THE PITTING OF SCREW PROPELLERS and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
The improvements relating to this invention consist in placing, between one or more
of the joints or couplings of screw propeller shafts of steam ships, simple or compound
discs of any kind of material, or materials, which is, or are, either good or bad
conductors of electricity, or the two or more kinds of material may be used in any one
or in all of the joints or couplings in any propeller shaft. Where the simple disc, or
discs, of bad conducting material only are used I insulate the bolts which are used to
fasten or bind the said joints or couplings of the screw propeller shaft together. The
discs may be made of any convenient shape or size to suit the ends of the shaft, or the
couplings may be recessed to receive the same, and the bolts may be insulated their
whole length or only where they come in contact with the flanges of the joints or
couplings of the screw-propeller shaft, and I place one or more springs, combs, or
brushes or other kind of collectors of electricity in contact with the coupling, or with
the shaft, or with both, such collector or collectors being connected to insulated
conductors to convey any electricity clear of the ship, or to be collected for any useful
purpose. I do not confine myself to any kind of material for the aforesaid discs and
insulators for the bolts, as any kind may be used such as ebonite, vulcanite, paraffin
paper or other bad conductor of electricity. Or the simple disc or discs may be made
of any kind of good conducting material, such as copper or other material, and be
shaped to suit the ends of the propeller shafts and the couplings, and where these
simple discs of good conducting material are used it is not essential that the bolts,
which fasten or bind the joints or couplings together, should be insulated, but I prefer
to make the disc, or discs, larger than the diameter of the coupling or couplings of the
propeller shaft, and to place the collectors in contact with one or both sides of the discs,
either with or without the collectors in contact with the couplings and the shaft. Or
I use two or more discs in one or more of the joints or couplings of the propeller-
shaft, one disc made of any kind of material which is a bad conductor of electricity
and the other disc made of any kind of material which is a good conductor of electricity
and so place them that one flange of any joint or coupling of the propeller shaft is in
contact with the bad conducting material, and the other flange is in contact with the
good conducting material. I do not limit myself to any kind of material of which
the discs may be made, nor to making them of any particular size or shape, as the
discs which project beyond the periphery of the joints or couplings of the propeller

page_text: shaft may be straight, fluted, plain, or bent into any convenient form to facilitate the
collecting of any electricity that may be contained therein, or for its conveyance clear
of the ship, or to be used for
any purpose. The discs, of either description, have holes
made in them for the bolts, which fasten or bind the joints or couplings of the screw
propeller shaft together, to pass through, and the discs are made to suit the ends of
the shaft, so that when the joints or couplings are put together with the discs between
them, all may be screwed together by the bolts, so that the discs may arrest or deflect
any current of electricity that may be in the screw propeller shaft, and the collectors
and their conductors may be varied to suit the various circumstances in each case.
Having now particularly described and ascertained the nature of my said Invention
and in what manner the same is to be performed I declare that what I claim is
1. The manufacture or construction and the application of simple and compound
discs of good or bad conductors of electricity to screw propeller shafts of steam ships
substantially as hereinbefore described.