Improved Apparatus for Automatically Ascertaining the Inaccuracy of a Clock, and for Automatic Delivery of Corrected Time Signals from such Clock.
Year: 1895

page_text: Date of Application, 10th Oct., 1895-Accepted, 7th Dec., 1895
COMPLETE SPECIFICATION.
Improved Apparatus for Automatically Ascertaining the Inaccuracy
of a Clock, and for Automatic Delivery of Corrected Time Signals
from such Clock.
1, ADOLF FRANKE of 4 Bachstrasse, Berlin in the Empire of Germany Doctor
of Philosophy, 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:-
n
To automatically control the accuracy of a pendulum clock at a distant spot, it is
necessary, especially when fractions of the pendulum oscillations have to be
correctly given, to directly influence the pendulum itself. It is possible by keeping
up a periodical electric current, to cause the oscillations of the pendulum to remain
in complete synchronism with the regulator clock. This requires however a
permanent circuit between the regulator clock and the clock commanded by it,
which ordinarily is not the case especially when considerable distance separates the "
two. In the latter case the circuit can only occasionally be made serviceable for
the purpose referred to, perhaps once in the day and only for a short time, and it is
therefore necessary to depend on the action of a single current.
Now to influence
the oscillations of a pendulum with a single current is very difficult, especially in
the case of the heavy seconds-pendulums which are required for greater exactness
siure the clock between two current-impules-that is to say during a day, may not
bave made any appreciable gain or loss.
It is therefore more easy to obtain the exact registration of time, from clocks
placed in distant spots by renouncing the exactness of the clock itself, and devising
instead an arrangement for registering its inaccuracy either by hand or automatically
only within certain limits, say 10 seconds, to determine the inaccuracy most exactly
every day by the electric current and to make it readable on the clock face.
For this purpose 1 use a small correcting work such as a spring or other running
train with very even revolution or a clock work with a very quickly oscillating
balance (for instance oscillating in second). This is arrested by the armature
of an electromagnet and only freed when the armature is attracted. The hand or
indicator pertaining to this work makes for instance a revolution in 20 seconds, its
dial being divided into tenths of seconds.
Reference being made to the annexed drawings.
Fig. 1. shows the said dial divided into twenty main divisions each of which is
sub-divided in tenths.
Fig. 2. is a diagram illustrating the electric connections.
To ascertain by means of such a work the defects of a clock with reference to
the regulator the correcting work is put in action by closing a local curcuit before
current is sent through the main circuit from the regulator. The correcting work
then begins to run, and runs until its hand has arrived on the lowest point of the
dial.
In this position the correcting work interrupts the local circuit and remains
stationery.
The regulator will send every day at the same time, let us say for instance
exactly at four o'clock in the morning, a current which again releases the correcting
work. This current is intercepted by the controlled clock as soon as the latter
indicates 10 seconds past 4 o'clock. If both clocks are exactly in concurrence the
current will last exactly 10 seconds. The correcting work is therefore not

page_text: intercepted until it has made just half a revolution, and its hand is therefore
arrested at its highest point thus showing that the inaccuracy of the clock is zero.
If however the controlled clock is say 23 seconds fast, for instance, the duration
of the main current will be shortened for that time, the correcting work will not
run so far accordingly and its hand will remain stationary at 23 seconds. On the
other hand if the controlled clock is slow the duration of the current will be
lengthened accordingly and the hand will run beyond the zeru point of the dial.
Thus it may be read at any time on the dial what inaccuracy or difference the
clock hnd at the time of putting in circuit, and it the sume has worked sufficiently
to register no remarkable difference between two time comparisons, the exact time
statement may be guaranteed.
It is however a condition that the correcting work should not be inaccurate in
the short time of its revolution but this can be easily obtained.
A correcting work of the kind can be used at the same time to cause the
delivery of exact single time signals from the controlled clock.
The delivery of time signals of extraordinary accurary, as required, for instance,
for the shipping service on the consts can naturally only be obtained from a
observatory which is capable through continuous astronomic observations of
controlling the running of clocks even to fractions of seconds.
If however the observatory is situated at a great distance from the cast it is very
often impossible because of the very extensive ordinary telegram circulation to
institute a direct telegraphic communication at midday when the time ball has to
fall.
To avoid this a controlled cluck and a correcting work are fitted at the time-ball
station and the latter is put in circuit in the above describe manner with the
observatory clock at a time when the circulation of the telegraphic message is
very small say for instance at 4 a.m. In the position given at this comparison of
time the hand of the correcting work remains until the release of the time ball
has to take place. This is usually the case at full hours mostly at 12 o'clock
midday.
As soon as the clock in the time ball station indicates 10 seconds to 12 o'clock
its local current is set in action for exactly 20 seconds, the connecting work runs
during this time, and therefore stops after exactly one revolution. At the moment
at which the hand of the correcting work passes the lowest point on the dial, a
contact is made which acts on the time ball. This moment will fall always at
the full hour quite independent of the inaccuracy of the clock as will be shown by
the following explanation.
If the clock is necurate the hand of the correcting work will point to the highest
point of the dial. From here to the moment of contact of the ball circuit the
correcting work has to make just half a revolution ... 10 seron Is, and as it was
released exactly 10 seconds before the fall bour the falling of the time ball will
occur precisely at 12 o'clock.
If however the clock is inaccurate, if it is for instance 23 seconds fast, then the
duration of the current will be shortened for that amount when comparing time in
the morning at 4 o'clock. The hand will then rennin stationery for a corresponding
amount before the zero point of the dial. From this point to the release of the
time ball the correcting work will have to run 123 seconds instead of 10 seconds,
but as through the inceuracy of the clock it will be released 123 seconds before
the exact hour (according to observatory time, the moment of acting on the tim
ball will again occur precisely at the full hour. Of course it is the same when th
clock is slow. Then the correcting work will have to make more than half
revolution when comparing time and will run less than 10 seconds upon its second
release thus again eliminating the inaccuracy.
Referring to Fig. 2 from the local battery having one pale led to earth a wire
lends to the binding post 3 of the clock, from there through contacts and C
from post 4 of this clock to post. 2 and the electromagnet M of the correcting work,
thence to earth. The armature of electromagnet M is attached to a lever A to

page_text: which is also fixed spring F the other end of which presses the balance U of the
lockwork and thus prevents its movement except while M. keeps its armature
ttracted, when spring F releases the balance and the correcting work can only run
during this time. The correcting work can therefore act only when contacts C
and Callow the current to pass which takes place every hour for 20 seconds.
10 seconds before the full hour the contact C2 is closed by the falling of a lever
on the escapement wheel of the clock. 10 seconds after the full hour by the falling
of a second lever contact C' is intercepted and contact C³ closed at the same time,
when to prevent the formation of sparks on the very sensitive contact a way is
found for the extra current over post 2 of the clock to the ground.
If the hammer of the time ball is not lifted the current will not find a way
back to earth even when the contacts C1 and C² are closed and the correcting work
remains in repose. Only in the night at 3 a.m. when the switch D' fitted on the
left of the 24 hours dial is in action the current can circulate from electromagnet M
to the contact C', post 3 of the correcting work, post 5 of the clock, switch D', and
post 2 of the clock.
At
The correcting work runs then until the contact C is intercepted which takes
place as soon as the spring of this contact falls into an indent on the face of the
correcting work when the hand of the latter has arrived at its lowest point.
4 o'clock switch D' is again pushed back and when the clock closes the contact C*,
the local current cannot circulate as yet. Only when the relay K attracts its
armature through the current sent through its coil from the observatory or head
station; the circuit through post 4 of the correcting work and the working contact
of the relay is closed and remains so until the clock breaks the contact C
10 seconds after the full hour. Even if the relay should release its armature to
early the current will not be interrupted because through the attraction of electro-
magnet Ma second circuit will be formed through contact H, post 1 of the
correcting work, post 1 of the clock, switch D and post 2 of the clock.
At other hours the correcting work remains stationary for none of its current
circuits are completed.
If the time ball is to fall at 12 o'clock it will be wound up a few minutes before 12
its release hammer will be lifted and retained by the armature of electromagnet M
contact fitted on the hammer of the time ball will thus be put in circuit. When
at 10 seconds before noon the clock closes the circuit of the local current, the latter
passes over contact C³ over post 5 of correcting work through the wire to the time
ball, the electromagnet M' the time ball release and contact Z'. At this moment
the electromagnet M' is energized, but the hammer can only fall a very little, at
the same time the electro magnet M of the correcting work is set in action and the
latter begins to run. Here also a branch circuit is formed over contact H and
the resistance W to earth. As soon as the hand of the correcting work passes
the lowest point of the dial, contact C is interrupted because its spring falls
into the indent of the plate moved by the correcting work and thus separates itself
from the contact screw, the electromagnet M³ of time ball is then without current,
the hammer falls and releases the time ball.
The current in electromagnet M disappears only because of the short circuit.
over contact H, when the clock 10 seconds after the full hour interrupts the local
current. The correcting work has then run exactly 20 seconds and has accomplished
just one revolution.
The switch contacts which are fitted on the right hand side of the 24 hours dial
are actuated at 4 o'clock and serve to connect the wire from the observatory with
the relay R.
Having now particularly described and ascertained the nature of this said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. An apparatus for automatically ascertaining the inaccuracy of a clock with
reference to a regulator at a
distann unsisting at a sunniva train or plank wal

page_text: with short time revolution which can be stopped at any point by an electromagnetic
device, which work is first released by the clock to be controlled and arrests itself
afterwards in a certain position to be again released by the regulator and again
stopped by the clock, thus indicating by the position of its hand the measure of
the inaccuracy of the clock.
2. An apparatus for automatic delivery of accurate time signals by an
inaccurate clock consisting of the apparatus described in Claim 1 combined with
an electric circuit system operating every time in a particular position of the
correcting work which latter therefore through its particular position actuates it
sooner or later so as to eliminate the differences caused by the inaccuracy of the
clock and cause the time signal to be given at the right moment.
3. The construction of an apparatus for showing inaccuracy of the clock and
giving corrected time signals substantially as described and illustrated in the
drawings.
100-
HERBERT HADDAN & Co.,
18 Buckingham Street, Strand, London, W.C., Agents to Applicant.