IMPROVEMENTS IN ELECTRIC LOGS
Year: 1884

page_text: I WILLIAM GEORGE ROTHWELL of Liverpool in the County of Lancaster, Master
Mariner do hereby declare the nature of my said invention for IMPROVEMENTS IN
ELECTRIC LOGS to be as follows:-
"
:
The object of the invention is to provide a log which shall measure uninterruptedly
the motion of a ship or vessel through the water and shall record both the total
motion of the ship or vessel or the distance covered during a voyage and the speed
of motion of the said ship or vessel during a given time.
.
A log under my invention consists essentially of a screw or like appliance free to
rotate provided with a contact maker and breaker acting periodically and connected
by an electric circuit with duplex recording apparatus of novel construction
The screw or like appliance is preferably constructed with advancing blades and
is attached to the vessel or other structure below the water line.in any convenient
manner so as to make and break electrical circuit. I prefer that the said screw or
like appliance should fit into a groove or grooves or on or around projecting pieces
secured to or formed in or on the side of the ship or vessel at the desired point.
From the said screw or like appliance an insulated wire or wires is or are led to the
duplex recording apparatus and to a battery. The duplex recording apparatus
consists of two trains of wheels and sets of indicators, one of which records
continuously the motion of the screw or like appliance whilst the other has free or
reversible indicators actuated periodically by means of a clock or time keeper so as
to return to Zero.
The action of the log is as follows:-The screw or like appliance is caused
to revolve by the motion of the ship or vessel through the water past the
said screw or like appliance. The electrical circuit is made and broken during each
revolution or more or less often as arranged. Each time the circuit is made and
broken both trains of wheels and indicators are actuated by electro magnets and
pawls or their equivalents. The one train of wheels is constantly moved in the
same direction and serves to show the total motion. The other train of wheels is
acted upon periodically by means of a clock or time keeper say every hour so as to
return to Zero in any well known or suitable manner. By observation of the
former the total distance travelled is shown the latter indicates the speed for the
time being.
12
T1004

page_text: position. If desired a chamber may be provided within the ship or vessel for
containing the log and an opening on side at the desired point through which the
log is projected when in use doors being provided if necessary between the chamber
and the opening. 9 are the electric circuit wires from the contact maker and
breaker 5 to the electro magnet 10 on the recorder 11. 12 battery, 13 armature
rocking on pivot 14 held out of contact with the electro magnet 10 by the spring 15
and provided with a pawl 16, 17 screw and nut appliances for adjusting the motion
of the armature. 18 ratchet wheel acted on by the pawl 16. 19 detent and spring
for preventing the ratchet wheel 18 from moving more than one tooth at a time, the
actuating tooth-by-tooth mechanism for the ratchet wheel may be made in numerous
ways and such mechanism is well known. The ratchet wheel 18 is secured on the
same spindle as the wheels 20 and pointers 21. The wheel 20 gives motion to a
train of wheels 23 and pointers 24. 25 spring with wheel geared into the train 20
to assist in overcoming friction and assist the armature and pawl mechanism in
giving motion to the said train. The wheel 20 gives motion to the wheel 26 and
the wheel 27 on the train 23 to the wheel 28. The wheels 26. 28 revolve on studs
secured to the armature 29 and actuate the pointers 30. 31 through friction discs 32.
The armature 29 is free to slide on guides 33 and is held with the wheels 26. 28 in
contact with the discs 32 by means of springs 34 and is withdrawn therefrom by
means of the electro magnet 35. The spindle of the pointer 30 has an armature 36
attached thereto in such position that the actions of of gravity and the electro
magnet 37 will cause it to carry the pointer 30 to Zero whenever the pointer spindle
is free to rotate. The spindle of the pointer 31 which never makes more than one
complete revolution is fitted with a weight and thread 38 for returning the pointer
to Zero. It will be obvious that the pointers may be returned to Zero at the
required times by any other suitable means. 39 electric wires and battery connected
to the electro magnets 35 and 37 and to studs 40 on the clock 41. The minute
hand of the clock is provided with a contact maker. It will be obvious that the
connections to the clock may be arranged for completing circuit every hour or other
specified period. A second circuit may be applied to the clock to ring a bell and
draw attention to the fact that the releasing circuit 39 is about to be completed.
The action of the apparatus is as follows:-The revolution of the screw 1. causes
an electric circuit to be made and broken through the wires 9 periodically so as to
give intermittent motion to the armature B wheel 18 train of wheels 23 and
wheels 26. 28. Each hour the minute hand of the clock 41 completes circuit through
the wires 39 withdraws the armature 29 and releases the wheels 26. 28 so that the
pointers 31. 30 return to Zero. By observing the position of the pointers of the top
train of wheels the total distance travelled will be known whilst the lower pointers
will show the distance travelled each hour.
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 :-
First. The combination of screw and recording apparatus substantially as herein
set forth.
Second. In combination with screw logs duplex recording apparatus substantially
as herein set forth.