AN IMPROVED ELECTRIC LOG AND REVOLUTION INDICATOR
Year: 1884

page_text: We PERCY SCOTT of Winterbourne, Upper Norwood in the county of Surrey
Lieutenant R.N. and ARTHUR TEMPLE HOPETOUN SCOTT of Trinity House, London
in the county of Middlesex, Trinity House Clerk, do hereby declare the nature of
the said invention for AN IMPROVED ELECTRIC LOG AND REVOLUTION INDICATOR
to be as follows:-
This Invention relates to an improved electric log and revolution indicator
whereby the speed of a ship or of her engines may be ascertained with precision
almost at a glance and at any moment required.
The log and engine counter may be used separately but would generally be
combined in one instrument in steam ships. Each is based on the employment of a.
combined time glass and electrical circuit closer whereby an electrical circuit is'
kept closed during any unit of time adopted in combination with a make and break
actuated by the log or by the shaft whose revolutions are to be counted, and with
a step by step recording instrument whereby the making and breaking of the
circuit during the given unit of time is recorded or translated in the form of the
corresponding number of knots per hour or revolutions per minute or according to
any other system of calculation preferred.
The combined time glass and circuit closers consist of a mercurial time glass
resembling a sand glass in which mercury takes the place of the sand. At the
neck or other convenient part of the glass two wires are inserted and terminate
within the bore so that the mercury in its passage must place them in electrical
contact, these wires being connected with respective portions of a battery circuit.
They may also serve as an axis upon which the time glass may be oscillated.
the same circuit are placed the electro magnet of the step by step recording instru-
ment and the make and break for producing the necessary interruptions in the
current for the operation of the said instrument.
In
In the case of a revolution counter for the engine or screw shaft this make and
break consists merely of a series of contact studs on the shaft which come
successively into contact with an insulated spring in electrial connection with one
pole of the battery through the metallic circuit and the instruments above men-
tioned whilst the contacts may be in electrical connection with the other pole
through the shaft and the external water or the skin of the ship.
In the case of the log the revolution of the vanes is caused to make and break
the circuit which is partly formed by the towing line to which the log is attached
and partly by the water.

page_text: For this purpose the log (which may be provided with the ordinary mechanism
for indicating the total distance run) would be towed by an insulated wire in
electrical connection with an insulated spring contact contained in the casing of
the log. The other and moveable contact is a spring or other device actuated by a
lever which is oscillated by a wiper on the revolving vane shaft and is caused at
each oscillation of the lever to make contact with the insulated spring. This
contact is in electrical connection by the casing of the log water and the skin of
the ship with the opposite pole of the battery to that with which the towing wire
is connected, but the chamber which contains the make and break arrangement is
made absolutely water-tight.
To accomplish this and yet transmit the motion of the vane shaft to the lever
contact the chamber containing the make and break is separated from the
remainder of the log by a water tight partition through a hole in which the
lever contact passes a flexible sleeve attached to the partition around said hole
and to the end of the lever which passes through it excluding the water whilst
permitting the oscillation of the lever.
The vanes and mechanism in connection therewith are arranged to rotate with
the minimum of friction whilst the casing containing the make and break is
prevented from partaking in the revolution of the vanes by the resistance to
torsion of the towing wire.
When the log and revolution indicator are combined as would generally be the
case the same time glass and recording instrument would be used for both a switch
being provided to throw either one or other into the circuit as required.
The dial of the recording instrument would be suitably graduated to indicate the
knots and tenths per hour, or in revolutions per minute according to the period of
time for which the time glass runs and the pitch of the log vanes or the number of
contacts on the shaft as the case may be.
The time glass may be inverted by hand each time it is desired to ascertain the
speed either of the engines or ship or it may be inverted periodically by suitable
clockwork and a permanent record obtained on a tape actuated by the same
clockwork by means of a pencil or marker actuated by the same electro magnet
as the indicator.
DL: 00
Jaha 100A.
We PERCY SCOTT of Winterbourne, Upper Norwood, in the County of Surrey
Lieutenant RN, and ARTHUR TEMPLE HOPETOUN SCOTT, of Trinity House,
London, in the County of Middlesex, Trinity House Clerk do hereby declare the
nature of our invention for "AN IMPROVED ELECTRIC LOG AND REVOLUTION 4
INDICATOR and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
"
This Invention relates to an improved electric log and revolution indicator
whereby the speed of a ship or of her engines, may be ascertained with precision.
almost at a glance and at any moment required.

page_text: The log and engine Counter may be used separately but would generally be
combined in one instrument in steam ships. Each is based on the employment of a
combined timer and electrical circuit closer whereby an electrical circuit is kept
closed during any unit of time adopted in combination with a make and break
actuated by the log or by the shaft whose revolutions are to be counted and with
an indicator whereby the circuit indicated by number of knots per hour or
revolutions per minute corresponding to the number of times the circuit is made
and broken during the given unit of time, is indicated.
Reference is to be had to the accompanying drawings forming part of this
specification wherein figure 1 represents a face view (partly broken away) of the
indicator. Figure 2 shows a rear view and figure 3 a detail of the same Figure 4
represents the make and break applied to the engine or propeller shaft Figure
is a central longitudinal section of the mercurial timer and circuit closer Figure 6 is
a longitudinal section of the electrical part of the log and Figure 7 represents the
rotator for the same.
The instrument shown in figure 5 consists of a mercurial timer resembling a sand
glass in which mercury takes the place of the sand and during its passage through
the neck of the instrument closes a metallic circuit The vessel A is made
preferably of steel and is mounted on trunnions a turning in brackets B and is
in electrical connection with the same. Through one of the trunnions passes an
insulated platinum wire C which terminates just within the neck of the vessel A. so
that the mercury in its passage will make electrical connection between said wire
and vessel A. Through the other trunnion may be passed a regulating screw d
adjusted by micrometer gear in order to contract more or less the bore of the neck
for the purpose of timing the flow of the mercury. The two ends of the vessel A
may be put in communication by a bye pass tube a¹ and the vessel may be filled
with an atmosphere of inert gas to prevent oxidation of the mercury or it might be
exhausted of air.
In the same circuit are placed the electro magnet E of the indicator figures 1
and 2 and the make and break for producing the necessary interruptions in the
current for the operation of the said instrument.
When the log and engine counter are combined as would generally be the case
the same timer and indicator would be used for both, a switch s being provided to
throw either one or other into the circuit as required.
In the case of a revolution counter for the engine or screw shaft the make and
break consists of a series of wipers ƒ figure 4 on the shaft F that come successively
into contact with an insulated spring g and cause it to make contact with another
springh (which may when desired be switched into electrical connection with one
pole of the battery through the metallic circuit formed by the wires c c c³ the
mercurial timer and the electro magnet E) the insulated spring g being in con-
nection with the other pole through the wire c c and the external water or the
skin of the ship.
In the case of the log, the revolution of the rotator figure 7 is caused to make
and break the circuit.
For this purpose the log (which might be provided with the ordinary mechanism
for indicating the total distance run) is towed by an insulated wire i which may
when desired be switched into connection with one pole of the battery through the
mercurial timer and the indicator as in the former case and which terminates in a
spring contact k contained within a watertight compartment of the casing of the
log Figure 6. The other and moveable contact is a spring actuated by a lever m
which is oscillated by a wiper n on a shaft n' actuated through reducing internal
gear by a shaft o to which the rotator is attached. The spring (which is in
electrical connection by the metal casing of the log the water and the skin of the
ship with the opposite pole of the battery to that with which the towing wire is
connected) is caused at each oscillation of the lever m to make contact with k
The rotator is a simple vaned cone towed a short distance astern of the electrical
portion of the instrument by a line attached to the shaft o which turns against ball

page_text: bearings to receive the pull of the rotator. In order to render the chamber
containing the make and break arrangement absolutely water-tight and yet
transmit the motion of the shaft o to the contact spring the said chamber is
separated from the remainder of the log by a water tight partition p through a hole
in which the lever m passes a flexible watertight sleeve q formed of a piece of
indiarubber tube is attached, to a flange on the partition p around said hole and to
the end of the lever m which passes through it the sleeve thus excluding the water
from the front chamber whilst permitting the oscillation of the lever.
The dial of the indicator would be suitably graduated (to indicate knots and
tenths per hour and revolutions per minute) according to the unit of time for which
the mercurial timer is made to run. The indicator consists of a spring barrel and
train controlled by the pallets of an escapement lever e (shown detached in figure 3)
actuated by the armature of the electromagnet E¹. The indicator hand is carried
by a tubular arbor fitting spring tight on the centre arbor, and provided with a
heart cam t operated by a spring push rod u for returning the hand to zero after
each observation The timer may be inverted by hand each time it is desired to
ascertain the speed either of the engines or ship or it may be inverted periodically
by suitable clockwork and a permanent record obtained on a tape actuated by the
same clockwork by means of a pencil or marker actuated by the same electro
magnet as the indicator.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is :-
1. The combination in an electrical circuit of a mercurial timer and circuit closer
as herein described an electro magnetic indicator and a log fitted with a make and
break actuated by a rotator the whole arranged for operation substantially as
herein shown and described for the purpose specified.
2. The combination in an electrical circuit of the mercurial timer and circuit
closer as specified, an electro magnetic indicator and a make and break actuated by
the engine or propeller shaft substantially as herein shown and described for the
purpose specified.
3. In an electric log and revolution indicator the use of a mercurial timer and
electrical circuit closer constructed and operating substantially as herein specified.
4. In an electric log the combination and arrangement of the partitioned log
casing the flexible sleeve the lever and its operating mechanism whereby the
motion of a rotator is imparted to an electrical make and break whilst excluding
the water substantially as shown and described.
Dated this 20th day of Navaho 1004.