Improvements in Ships' Logs.
Year: 1897

page_text: Date of Application, 18th May, 1897
Complete Specification Left, 16th Feb., 1898-Accepted, 9th Apr., 1898
Improvements in Ships' Logs.
We, GEORGE WALKER, of 95, Leadenhall Street, London, Engineer, and ALFRED
HILLYARD MITCHELL, of 95, Leadenhall Street, London, Engineer, do hereby declare
the nature of this invention to be as follows:-
In ships logs the log is generally fixed at the end of a rope and then thrown
overboard. The rotating log generally consists of a screw or piece of rope which
revolves as it is drawn through the water. These revolutions are transmitted by
the twisting of the connecting rope to such part of the ship as it may be necessary
to take readings. This transmission of power along the twisting rope prevents
delicate readings being taken, as it causes the rotator to slip.
According to this invention we provide a means of reading the revolutions of
the screw without transmitting the revolutions along the rope, and also of enabling
the indications to be read in various parts of the ship at the same moment.
For this purpose instead of fastening the rotator or screw rigidly to the rope
we fix it to a spindle upon which it is free to revolve. To further reduce the
friction, the screw runs on the spindle on ball bearings, anti-friction wheels or
rollers or otherwise.
The spindle is fixed rigidly to the rope, the top end of the rope being fixed to
any convenient part of the ship.
Attached to the spindle but insulated from it is a metal contact maker.
On the screw revolving each revolution makes contact with the insulated portion.
Two wires are carried up to the ship, alongside or woven into the rope, con-
nected with a battery or other electrical generating appliance, and an indicator.
The contact maker can also be fitted in a swivel, and the rotator or screw attached
to the swivel by a shackle, the swivelling part running on anti friction wheels
or rollers, ball bearings or otherwise.
In cases where it is not necessary to indicate each seperate revolution, an indi-
cation may be sent for a number of revolutions in the following manner.
A worm is fixed to the revolving spindle, into this are geared cogwheels of dif-
ferent sizes; to each wheel is fitted a projecting arm, and each revolution of the
cogwheel brings this arm in contact with a contact maker, allowing a current to
flow. If two cogwheels be used, each with a different number of teeth, contact
can only allow a current to flow when each projecting arm makes contact at the
same time, and this will be when the number of revolutions of the worm are
equal to the lowest common multiple of the number of teeth in each cog.
The indicator consists of an electro magnet, and armature, and is connected
by a pawl and ratchet with a counter. When contact is made, the current flows
through the completed circuit causing the electro magnet to act on the armature
and set the counter in motion.

page_text: Any number of indicators may be used, either in direct circuit or worked with
a relay.
Doted this 4th day of Mor 1907
We, GEORGE WALKER, of 95, Leadenhall Street, London, Engineer, and ALFRED
HILLYARD MITCHELL, of 95, Leadenhall Street, London, Engineer, 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:-
In ships logs the log is generally fixed at the end of a rope and is then thrown
overboard.
The rotating log generally consists of a screw or piece of rope which revolves
as it is drawn through the water. These revolutions are transmitted by the twisting
of the connecting rope to a recording machine fixed on the stern part of the ship
to take readings.
This transmission along the twisting rope prevents delicate readings being taken
as it causes the rotator to slip.
According to this invention we provide apparatus as shewn in sectional elevation
Figure 1, in transverse section Figure 2 in plan Figure 3 and in general arrange-
ment Figure 4, of the accompanying drawings.
A is a spindle to which the rotator may be fixed direct or by means of a shackle
or other connection.
וי
On the spindle A at E is a worm which is geared into two worm wheels I and G.
Attached to these wheels or to the spindles of them so as to rotate with them
are two arms H and K.
O is a collar with grooves cut in it at B for forming ball bearings and this
collar is held in position by the nut D.
Land M are two springs fixed onto a vulcanite or other non-conducting material
end N, and wires are carried through to the outside of the apparatus care being
taken that neither L or M or the wires connected thereto are able to form elec-
trical contact.
The whole of this gear in enclosed in a case Q, and a shackle P held in position
by a pin O passing through N is provided for fastening the apparatus to the
towing rope.
When A revolves the worm E causes the wheels F and G to revolve and as each
goes round the arms H and K will touch the springs L and M. When A has
revolved a number of times equal to the lowest common multiple of the number
of teeth in the wheels F and Ĝ then H and K will touch L and M together and
a complete electrical contact will be made by L and M through the arms H and K
the wheels F and G and the worm E.
If the two wires from L and M be connected with a battery as shewn at R in
Figure 4 and a counter S be introduced into the circuit, every time contact is
made the current from R will flow along the completed circuit and cause the
counter to indicate the number of revolutions made by the log or to indicate the
distance the ship has travelled.
The battery can be placed in any convenient part of the ship and the indicator
may also be placed on the bridge, in the charthouse, the engine room, or else-
where or one may be placed in each place referred to thus doing away with the

page_text: necessity of going to the stern of the vessel to take readings which exists with
the present apparatus.
Having now particularly described and ascertained the nature of our said in-
vention, we declare that what we claim is:-
1. Ships logs or swivels for ships logs in which the rotator runs upon ball
bearings substantially as described and shewn in the drawings.
2. Ships logs or swivels for ships logs in which the revolutions of the logs are
transmitted to an indicator on the ship by means of an electric current which
is made to flow as the log revolves, substantially as described.
3. Ships logs or swivels for ships logs in which the spindle A is fitted with a
worm E geared into worm wheels F and G connected to arms H and K which
make contact with springs L and M simultaneously when the spindle A has re-
volved a number of times equal to the lowest common multiple of the number
of teeth in the wheels F and G, thereby forming a completed electrical circuit
between L and M substantially as described and shewn in the drawings.
4. Ships logs or swivels for ships logs in which the revolutions of the log
are after the expiration of a given number of turns transmitted by an electric
current along a wire in circuit with a battery or other electrical generating ap-
pliance and an indicator or indicators substantially as described and shewn in
the drawings.
5. Indicators used in connection with an electric log in such a manner that
readings may be taken in any part of the ship or in several parts of the ship
simultaneously substantially as described.
16th of Waho 1800