Improvements in Electric Logs.
Year: 1888

page_text: Date of Application, 16th July, 1888
Complete Specification Left, 16th Apr., 1889
Complete Specification Accepted, 1st June, 1889
PROVISIONAL SPECIFICATION.
Improvements in Electric Logs.
1 NESBIT WILLOUGHBY WALLACE of 3 Eastern Villas Southsea in the County
of Hants Lieut. Col. Retired, H.M.S., do hereby declare the nature of this invention
(a communication to me from abroad by Percy Scott Commander R.N. H.M. Ship
Edinburgh, Malta) to be as follows
-
This Invention relates to improvements in electric logs for which Letters Patent
were granted to P. and A. T. H. Scott dated the 20th day of February 1884 and
numbered 3666; and it has for its object to provide a mechanical, in lieu of a
mercurial, timer and contact maker as described in the specification of the aforesaid
Patent and in the case of a log provided with means of indicating the total distance
run, to provide means of indicating when and for how long a period the log has been
rendered inoperative by the fouling of the rotator_so_that the total distance run may
still be ascertained approximately by calculation.
The contact maker and timer whereby an electrical circuit is closed for a definite
unit of time consists of an àrm rotating in contact with an interrupted ring of metal,
whereby a rubbing contact is made during the revolution of the arm, the latter being
actuated by a train of clockwork controlled by an escapement or fly, the clockwork
being either independent and wound up, each time it is used, by a handle provided
with a locking device acting also as a stop for the contact arm or it may be combined
with an ordinary clock which is kept going, the contact maker only being brought into
operation at required times.
The mechanism for indicating the fouling of the rotator, consists of an electro-
magnetic stop mechanism applied to act on the balance wheel or other convenient
going part of a clock, but which is kept inoperative so long as the intermittent
electric currents pass but which arrests the motion of the clock whenever it is
permitted to act by the continuous cessation or the continuous passage (as the case
may be) of the electric current consequent on the fouling of the rotator when the
contact maker is either on or off the contacts.
The said electro-magnetic stop mechanism may be applied to a separate clock, or
to one provided with two sets of hands and going mechanism, the one set being

page_text: independent and capable of being arrested by the stop mechanism-without affecting the
going of the other set, so that by comparing the two clocks or the two sets of hands,
as the case may be, the total period of stoppage may be ascertained and the total
distance travelled during the stoppage may be approximately computed.
This stop mechanism consists of detents operated by the armature of an electro-
magnet in combination with a locking wheel whereby the detents are held out of
engagement with the balance wheel except when they are permitted to fall into
notches in the wheel. So long however, as the current continues to pass inter-
mittently, the engagement of the detent with the notch of the locking wheel is but
momentary and the motion of the balance is not materially affected, but should the
current wholly cease the one detent, or should the current pass continuously the
other detent, will become permanently engaged with the locking wheel and so arrest
the balance.

page_text: 1 NESBIT WILLOUGHBY WALLACE, of 3, Eastern Villas, Southsea, in the County
of Hants, Lieut.-Col. Retired H.M.S. do hereby declare the nature of this invention
(a communication to me from abroad by Percy Scott, Commander R.N., H.M. Ship
Edinburgh" Malta) 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 improvements in electric logs for which Letters Patent
were granted to P. and A. T. H. Scott, dated the 20th day of February 1884 and
numbered 3666, and it has for its object first to provide a mechanical, in lieu of a
mercurial, timer and contact maker as described in the specification of the aforesaid
patent; and secondly in the case of a log provided with means of indicating the total
distance run, to provide means of indicating when, and for how long a period, the
log may have been rendered inoperative by the accidental fouling of the rotator in
order that the total distance run may still be ascertained approximately by
calculation.
Reference is to be had to the accompanying drawings forming part of this
specification, wherein figure 1 is a rear view partly in section, and drawn to an
enlarged scale, of the essential parts only of the timer and contact maker constituting
the first part of the invention, parts of known construction being omitted for the sake
of clearness.
This instrument is connected in circuit with the log and with the revolution
indicator described in the specification of the former patent aforesaid in place of the
mercurial timer herein described, whereby the electrical circuit is closed for a definite
unit of time during which the revolutions of the log are counted for the purpose of
ascertaining the then speed of the vessel. This timer consists essentially of a contact
arm and of an interrupted metallic contact wheel whereby a rubbing contact is made
with the arm during a revolution of the contact wheel which is performed in the unit
of time adopted the rotating contact being actuated by a train of clockwork controlled
by an escapement and wound up each time the instrument is used.
a is the fixed contact, being a light spring arm insulated from the frame of the
instrument and in electrical connection, by a terminal a', with the one wire say that
from the log or revolution indicator, and 6 is the rotating contact, being a whee!
against whose periphery the contact arm a bears when the instrument is in operation,
the periphery of the wheel being interrupted by one or more notches c or otherwise,
so as to limit the period of time during which the circuit is closed by the contact
of a and b. In the present example the wheel has two notches c and the unit of
time adopted is 30 seconds which is the exact duration of contact between a and b
during a half revolution of the latter. The wheel bis in electrical connection through
its arbor and the frame of the instrument, with the other terminal connected to the
indicator specified in my former patent. The wheel b is actuated from the arbor d
of a spring barrel through a wheel and pinion and its motion is controlled by an

page_text: .
escapement and balance wheel e actuated from the arbor of the wheel b. The spring
barrel is wound up each time the instrument is used by one stroke of a lever handle f
pivoted loose on the barrel arbor d and engaging by a pawl g with a ratchet wheel h
fast on the arbor d, which is moved to the extent of one tooth for one stroke of the
lever and winds up the spring barrel to an extent sufficient to cause the wheel b to
perform a complete half revolution which is performed in rather more than 30
seconds, the actual duration of contact between a and b being however accurately
timed by adjusting the regulator of the hair spring of the balance wheel e. During
the actual period of contact between a and b the balance wheel is vibrating freely,
the starting and stopping of the balance wheel é being performed whilst the spring
contact is opposite one of the notches c, so that the actual duration of the contact is
unaffected by any possible error in the swing of the wheel in starting and stopping.
The starting and stopping of the balance wheel is effected by a spring i carried by
an arm loose on the arbor of wheel b. but connected thereto by a long spiral spring
coiled about the said arbor and attached at one end to the arm and at the other
to wheel b, the arm / being also attached to a ratchet wheel also loose on the arbor
with which engages a fixed pawl . This spring i of which there are two corresponding
to the two notches c in the wheel occupies such a position relatively thereto and to
the balance wheel e that immediately after the contact a has fallen into one of the
notches the spring abuts against the periphery of the balance wheel e and arrests
it. This spring i also gives the balance wheel the impulse necessary to start it at
same time that the spring barrel.is wound up, and this is performed by a spring pawl m
carried by the lever handle engaging with a tooth n on the ratchet wheel / and
propelling the latter and with it the arm & carrying the spring i such a distance as to
move the spring clear of the balance wheel as indicated in dotted lines. In so moving
it, the end of the spring which bears with its sharp edge against the periphery of
the balance wheel e carries the latter round with it a sufficient distance to start it
swinging under the impulse of the spring barrel when the spring i quits it. This
independent motion of the spring i and ratchet wheel is permitted by the spring
connecting to b, which spring is thereby put in slight torsion and is prevented
from recoiling by the ratchet and pawl but is relieved of torsion by
the ratchet wheel and spring i remaining at rest until overtaken by the wheel when
the normal relation of the spring i to the wheel b is resumed.
Figure 2 is a rear view of the mechanism for indicating when, and at what
particular time, the rotator of the log may have become fouled. The mechanism
for indicating the fouling of the rotator consists of an electro-magnetic stop mechanisin
applied to act on the balance wheel o of a clock, but which is kept inoperative so
long as the intermittent electric currents pass but which arrests the motion of the
balance wheel and consequently of the clock whenever it is permitted to act by the
continuous cessation or the continuous passage (as the case may be) of the electric
current consequent on the fouling of the rotator at the moment when the contact-
maker in the fog is either on, or off, the contacts. The said electro-magnetic stop
mechanism is shewn as applied to a separate clock (but it may be applied to one
provided with two sets of hands and going mechanism, the one set being independent
and capable of being arrested by the stop mechanism without affecting the going of
the other set) so that, by comparison of the clock with another which is kept going
or by comparing the two sets of hands, as the case may be, the total period of
stoppage may be ascertained and the total distance travelled during the stoppage may
be approximately computed.
This stop mechanism consists of a spring detent or brake p pivoted at pl and
operated by the armature of an electro-magnet in combination with a locking
wheels whereby the detent p is held out of engagement with the balance wheel
except when it is permitted to fall into one of two notches t in the wheel s. So long,
however, as the current continues to pass intermittently, the engagement of the detent
with the notch of the locking wheel is but momentary and the motion of the balance
is not materially affected, but should the current wholly cease, or pass continuously,
the detent will become permanently engaged with the locking wheel and arrest the

page_text: balance. The locking wheels makes say one revolution per minute whilst the
armature vibrates, under the influence of the intermittent attraction of the electro-
magnet and the antagonistic spring, at such a speed that the brake p is almost
constantly held off the balance wheel o by the friction roller u carried at the end of the
armature passing to and fro beneath the stud v standing out from opposite sides of
a short downwardly projecting arm p² of the detent lever so that so long as the
vibration of the armature continues the stud v can only momentarily touch the
periphery of the locking wheel and the brake has no effect on the balance wheel.
Should the armature, however, remain stationary in either of its extreme positions
owing to the total cessation, or the continuous passage, of the current, the stud v
rests on the periphery of the locking wheel and when one of the notches t comes
beneath it, the detent is permitted to fall on to the balance wheel and stop it in which
position it is shewn in the drawing.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what
I claim is :-
1. The herein described timer and contact maker, consisting of a rotary interrupted
contact actuated by clockwork and controlled by an escapement in combination with
a stationary contact whereby an electrical circuit is closed for a given unit of time,
substantially as specified, and the employment thereof in combination with the
electric log and indicator described in the aforesaid previous patent, as specified.
2. In the herein described timer and contact maker actuated by a clockwork and
controlled by an escapement, as described, the combination with the balance wheel
of the herein-described means of starting and stopping it, substantially as specified.
3. The herein described mechanism for indicating the fouling of the rotator,
consisting of a detent or brake in combination with a notched wheel and the armature
of an electro-magnet in circuit with the make and break of an electric log, such as
that specified in the aforesaid patent, the armature being adapted, by its vibration,
to prevent the detent coming into action and the detent being applied to act on the
balance wheel of a clock when the armature ceases to vibrate, substantially as
specified.