Improvements in Apparatus for Measuring the Speed of Ships.
Year: 1888

page_text: Date of Application, 24th Aug., 1888
Complete Specification Left, 23rd May, 1889-Accepted, 24th Aug., 1889
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Measuring the Speed of Ships.
I. WILLIAM PUDDICOMBE GRANVILLE, of Ailsa Craig, Fairholt Road, Stoke
Newington, in the County of Middlesex, Electrician, do hereby declare the nature of
this invention to be as follows:-
Electric logs as at present constructed consist of two parts one of which is armed
with screw blades which cause it to rotate about the other part as the log is dragged
through the water. This motion causes electric currents to pass along a circuit of
which an insulatod wire (usually employed to tow the log) forms a part.
These currents actuate a step by step recording instrument upon the ship. Great
difficulty has been experienced in maintaining the insulation both of this wire and
also of the electrical apparatus in the log itself.
According to my invention I tow the log by an uninsulated wire
and do not employ the insulated wire as has always heretofore been the
practice. In order to render this possible it is necessary either to employ
a new log which is hereinafter described or to modify existing logs by making
them produce or work with currents of very low potential compared with those that
have always hitherto been employed and to lower their resistance and that of the other
electric apparatus so that the whole resistance of the circuit through the wire shall be
at any rate not much greater than that of the circuit through the sea. To assist in
this I prefer to use a wire of some good conductor, such as phosphor-bronze or copper
but steel or iron may be employed.
When the wire is of a different material to the sides of the ship, as both are exposed
to the sea water they form a battery which would set up a permanent current through
the recording instrument. I prevent this current by interposing between the recording
instrument and the ship's side a vessel filled with sea water and containing one or
more plates of the same metal as the conducting wire and also one or more plates of
the same metal as the ship's side, the plates of different metal being kept from touching
each other, and I connect the first named plate or plates to the recording instrument
and the last named plate or plates to the ship's side; or 1 connect the wire direct to
the ship's side and introduce into the circuit a condenser of large capacity; or I
prevent the current froin affecting the recording apparatus by connecting the conduct-
ing wire from the log to one end of the primary circuit of an induction coil the other
end being connected to the ship's side, and I connect the two ends of the secondary coil
to the recording apparatus.
In some cases, where the current is weak I employ a relay.
In using all existing electric logs with uninsulated wires it is also necessary to make
all the parts of the log exposed to sea water of the same material as the wire otherwise
a permanent current would be set up.
By using uninsulated wire I am enabled to use a very simple log and yet dispense
with the usual battery on board ship, but, as before stated an uninsulated wire can be
used with logs and especially magneto logs similar to those now made but modified as
above described.
In my apparatus I make the ship and the log itself to form a battery-for this
purpose I form one part of the log of some positive metal such as zinc, which is
normally kept metallically disconnected from the tow wire but is connected with it say
once in every revolution of the rotating part of the log, so that once in every
revolution a current is sent through the wire and actuates the recording instrument on
board ship.
In order to ensure the contact maker being kept dry 1 prefer to actuate it magneti-
cally in place of mechanically. It consists of an arm or needle free to rotate or

page_text: oscillate about an axis carried on the inner surface of a diaphragm, which forms one side of
a water tight box. On the outer surface of the diaphragm is a permanent magnet
carried by the rotating part of the log so that the contact maker is moved by the
magnet.
CARPMAEL & Co.,
A crents.
COMPLETE SPECIFICATION
Improvements in Apparatus for Measuring the Speed of Ships.
I, WILLIAM PUDDICOMBE GRANVILLE, of Ailsa Craig, Fairholt Road, Stoke
Newington, in the County of Middlesex, Electrician, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
Electric logs as at present constructed consist of two parts one of which is armed
with screw blades which cause it to rotate about the other part as the log is dragged
through the water. This motion causes electric currents to pass along a circuit of
which an insulated wire (usually employed to tow the log) forms a part.
These currents actuate a step by step recording instrument upon the ship. Great
difficulty has been experienced in maintaining the insulation both of this wire and also
of the electrical apparatus in the log itself.
According to my invention I tow the log by an uninsulated wire and do not employ
the insulated wire as has always heretofore been the practice. In order to render this
possible it is necessary either to employ a new log which is hereinafter described or to
modify existing logs by making them produce or work with currents of very low
potential compared with those that have always hitherto been employed, and to lower
their resistance and that of the other electric apparatus so that the whole resistance
of the circuit through the wire shall be at any rate not much greater than that of the
circuit through the sea. To assist in this I prefer to use a wire of some good
conductor, such as phosphor-bronze or copper but steel or iron may be employed.
All existing rotary electric logs may be divided into two classes. First: those in
which a battery is used on board ship the current from which is periodically started or
arrested by the movement of a contact maker in the log itself, and secondly the form
in which the revolving head rotates a magnet in close proximity to a coil of wire and
so producing an alternating magneto current which traverses the conducting wire and
actuates the indicator on board ship.
"
An uninsulated wire cannot practically be used with the first class because the
battery would very speedily be worked out as the sea would partially "short circuit.
the battery.
Logs of the second! class as at present made have a comparatively high resistance of
say about 80 ohms for the whole circuit including the indicator.
The potential or electromotive force, varies with the speed of the ship but it is
probably somewhere about 2 or 3 volts.
To make such a log capable of working with an uninsulated wire I reduce the
resistance of the log itself from say 30 ohms as at present to say 2 ohms. To do this I
use thicker wire in the coil of the log and therefore a shorter length, this necessarily
reduces the electromotive force from say 3 volts to about 7 volt and in the same way
I reduce the resistance of the indicator to about 1 ohm so that the total resistance of
the circuit would be 3 ohms against 80. The effect of reducing the resistance so
materially, is first to increase the current produced about S fold, and secondly to make
the path for the current up the wire through the indicator and ship's side to the sea
and log again so easy that a large portion of the current produced by the log chooses
that path instead of entering the sea direct from the bare wire especially as the surface
of the ship's hull is so enormous as compared with the small wire.
When the wire is of a different material to the sides of the ship, as both are exposed
to the sea water, they form a battery which would set up a permanent current

page_text: through the recording instrument. I prevent this current by interposing between the
recording instrument and the ship's side a vessel filled with sea water and containing one
or more plates of the same metal as the conducting wire, and also one or more plates of
the same metal as the ship's side, the plates of different metal being kept from touching
each other, and I connect the first named plate or plates to the recording instrument
and the last named plate or plates to the ship's side; or I connect the wire direct to
the ship's side and introduce into the circuit a condenser of large capacity; or I
prevent the current from affecting the recording apparatus by connecting the conduct-
ing wire from the log to one end of the primary circuit of an induction coil, the other
end being connected to the ship's side, and I connect the two ends of the secondary
coil to the recording apparatus.
In some cases, where the current is weak I employ a relay.
In using all existing electric logs with uninsulated wires it is also necessary to make
all the parts of the log exposed to sea water of the same material as the wire or of some
metal or alloy whose chemical behaviour in salt water is such that little or no difference
of potential exists between it and the metal of the ship's side otherwise a permanent
current would be set up.
By using uninsulated wire I am enabled to use a very simple log, and yet dispense
with the usual battery on board ship, but, as before stated, an uninsulated wire can be
used with logs and especially magneto logs similar to those now made but modified as
above described.
In my apparatus I make the ship and the log itself to form a battery - for this
purpose I form one part of the log of some positive metal such as zinc, which is
normally kept metallically disconnected from the tow-wire but is connected with it
say once in every revolution of the rotating part of the log, so that once in every
revolution a current is sent through the wire and actuates the recording instrument on
board ship.
In order to ensure the contact maker being kept dry I prefer to actuate it magneti-
cally in place of mechanically.. It consists of an arm or needle free to rotate or
oscillate about an axis carried on the inner surface of a diaphragm, which forms one
side of a water tight box. On the outer surface of the diaphragm is a permanent
magnet carried by the rotating part of the log so that the contact maker is moved by
the magnet.
In order that my said Invention may be more fully understood and readily carried
into effect I will proceed to describe the drawings hereunto annexed: -
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a full sized longitudinal section partly in elevation of a log constructed
according to my Invention.
Figure 2 is a transverse section on the line 1, 1, Figure 1.
Figure 3 is a transverse section on the line 2. 2. Figure 1.
Figure 4 is a fragmentary elevation of some of the parts shown in Figure 3.
The remaining Figures are separate views of the various parts.
The rear end of the log is made of two concentric cylinders A, A' of vulcanite, the
part A being grooved as shown in Figure 2 to receive the borse-shoe inagnet B,
the parts being held together by screws. C. Care metallic screw blades fixed to the
cylinder A. The part A' is perforated with a longitudinal hole lined with a metal
tube A 2 to receive a brass rod D₁ fixed to the cover D of a water-tight box, the rear
end being secured by a pin D 2 the head of which carries friction wheels D3. These
parts are shown in section and plan at Figures 5. As is shown in Figure 1 the friction
rollers D³ bear upon the end of the tube A 2 so that the rear part of the log revolves
freely on the rod D' with. little friction. The middle portion of the log consists of a
cylinder of zinc E shown separately at Figures 6 and the nose consists of a cap of
vulcanite F shown separately at Figures 7.
The cylinder E is mounted upon a tube of vulcanite G' which forms a prolongation
from the body G of the water tight box (see Figures, 8). The bottom of this box is

page_text: grooved as shown to receive the ends of the sides of the cover D which is somewhat
thinner than the width of the groove, leaving the space to be filled with resin-or the
like when the apparatus is put together so as to ensure a water-tight joint between
the two.
The nose F screws on to the end of the tube G¹ as shown, securing the parts together
H (Figures 9) is a rod of silicium bronze to the end of which the tow wire is attached.
The tow wire I prefer to make of silicium bronze. It would as usual be about one
hundred yards long whilst its thickness should be about 065 of an inch. The rod H
passes through the tube G' and screws into the base of a forked brass standard J
(Figures 1 and 4). The upper ends of the standard J. carry screws K which form the
pivots of a soft iron armature L (Figures 1. 3. and 4). In the fork of the standard is
fixed a vulcanite block M which carries a brass cross-piece. N. through which passes
two screw stops 0.0'. The point of the screw is of ivory whilst the point of the
screw O' is of platinum and is in metallic connection with the wire 02 which passes
to the brass connecting rod P. which screws into the brass collar Q (Figures 1 and 8)
which in its turn is screwed into the zinc cylinder E.
The action of the apparatus is as follows:-
As the log is dragged through the water the screw blades (cause the rear end to
turn relatively to the rest of the log. The magnet B as it revolves attracts in turn the
ends of the pivotted armature L causing the armature to rock upon its pivots K
making and breaking contact between it and the stop O' once in every revolution,
thus putting the zinc of the log into metallic connection with the metal of the ship,
the circuit passing through the rod P wire 02 screw stop 01 armature L, pivots K,
fork J, rod H, tow wire iudicating instrument, the ships sides and back by the sea to
the zinc.
It will be obvious that the arrangement may be reversed the magnet being carried
within the water-tight box and its armature in the revolving part of the log. The
arrangement of the parts also may be varied in a great variety of ways, but the con-
struction I have shown is very convenient.
Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
1. The combination, substantially as described of an electric log with an uninsulated
metallic tow line.
2. In apparatus such as is referred to in the first claim interposing between the
recording instrument and the ship's side a vessel filled with sea water and containing
a plate or plates of the same metal as the conducting wire and connected to the
recording instrument and a plate or plates of the same metal as the ship's side and
connected to it.
3. In apparatus such as is referred to in the first claim connecting the wire directly
to the ship's side and introducing into the circuit a condenser of large capacity.
4. In apparatus such as is referred to in the first claim connecting the conducting
wire from the log to one end of the primary circuit of an induction coil the other end
being connected to the ship's side and connecting the two ends of the secondary coil to
the indicating apparatus.
5. Ships' logs in which the ship, the log and the sea water form a galvanic battery
by which indicating apparatus is worked.
6. In electric logs placing the contact maker in a water tight box and actuating it
by means of a magnet.
7. Apparatus for measuring the speed of ships substantially as described and shown
in the drawings.
Dated this 99nd love of Ma.. 1000
W. P. GRANVILLE.