Early clocks and watches were
all mechanical in nature. Of the mechanical clocks the
Pendulum type keeps the best time, but can only be used on
The earliest clocks used mechanical methods to power the
movement. Weights that need to be periodically lifted or
a spring that needs winding. If you forgot to wind a
clock it would stop. This is as true today as is was
then. So a clock that winds itself would sure be
The first figures show the clock as it arrived. Although
there are some minor scratches on the outside paint the rest
looks very good. The movement number is 39580.
Marybeth Grisham has told me that the movement was made around
1900 - 1910 and later taken out of storage after 1938 when the
red synchronizing light came out to make a clock. The
synchronizer was available back in the 1900 time era, it's
just the red bulb that was added in 1938. The white
outer paint was commonly used in hospitals. The metal
bob was designed to provide both temperature and atmosphere
pressure compensation. The best clock of this
type she has seen lost 15 seconds after 70 of running (without
These clocks are still (2007) in use for the London
underground and/or transportation locations.
Around 1932, 1933 the Self Winding Clock Co was about to go
bankrupt and Western Union bought them and started making the
Western Union clocks based on the "F" movement that had been
in production for at least 24 years prior to that. So
the movement 39580 was made long before the Western Union
started using the Photographic Zenith Tube about 1934 (article
in Popular Astronomy
If either batteries or mains derived DC power is used for the
winding, if either fails for up to an hour or more, the clock
just keeps on ticking powered by the internal spring.
So, unlike most clocks, is very tolerant of power failures.
At the bottom of the cover there
is a knurled screw that fits in threads that are in the cover,
so you can loosen the screw while gently pulling back on the
cover and at some point the cover will hinge open. There
are two pins on the top of the frame that mate with holes in
the cover so now you can just lift the cover off. ( Fig
3 shows the cover upside down so you can see both the thumb
screw and the holes in the top)
Fig 4 shows the knurled thumb nut removed and both hands
lifted off. I've heard that the hole in the minute hand
is not square. But my minute hand will set down on the
square shaft in 4 positions without any binding. Also in
Fig 4 you can see the 4 slotted round head screws that hold
the dial. Although the minute hand might fit in any of
four positions, only one will be correct for the synchronizing
pulse. This was done so that lightning induced pulses
that arrived for most of the hour would not reset the clock
incorectly. So pay attention. If you loosen the
knurled nut holding the hands when the clock is mounted on a
wall the minute hand has a tendency to fall to 6:00.
It's only when the knurled nut is finger tight that the
friction clutch is working.
Fig 5 shows the clock now with dial removed and hanging on a
peg nearby and the clock running. First while holding
the clock on the table I wound the mainspring by turning the
wheel that the bottom coil turns when it vibrates. I
turned it until it hit the stop mechanism. Unbolting the
pendulum and giving it a push would allow the clock to run for
about 4 minutes. So I put a screw into a wall stud and
hung the clock on it. Just the movement involved started
the clock. The hands were at about 4:00 when it started
and at 5:25 there was a noise that I think were the contacts
closing asking for the electric wind, but now there's no
batteries connected. I'm writing this with the clock
showing 5:45 and I expect it to stop shortly. Stopped at
6:40 , run time about 2 hr 40 min. Set to 7:00, manually
wound spring, started.
The escapement shaft sticks out in front, probably so those
clocks that have the hole between the center and 12:00
can mount a second hand. I made up a paper dial 0.8"
diameter and made the center hole slightly larger than the
0.076" dia shaft so that the shaft would not rub on it.
Then made a second hand from 3x5 card stock with a center hole
slightly smaller than the shaft and just pressed it on the
The short pendulum is a 120 beats per minute so the second
hand moves in 1/2 second steps. The top of the pendulum
is connected to the clock's rear frame with a short flexible
metal band. Below the band there's a hinge that allows
the pendulum to move forward and backward. So that when
it's held solid against the frame with the shipping bolt
installed it can move to the rear slightly. The clock
movement connects to the pendulum by means of a stiff wire
that's forged into a hole in the escapement shaft then goes
behind the clock movement and down about 5" then has a
horizontal projection that fits a slot in the pendulum support
arm. This way when the movement is removed from the
frame the pendulum stays with the frame. I expect that
once adjusted the timing ability of a pendulum would not
change if a new movement was installed.
Some simple wire tracing shows the a blue wire connects to
both batteries and so must connect to + on one and - on the
other to get a series connection. So 3 volts (two "D"
cells in series) goes to the two free Green wires.
Making this connection causes the winding electromagnet to hum
and in maybe 10 seconds wind the clock. showing about
8:35. Goes about 30 minutes between windings.
The GE 43 red painted lamp did not light but it may not have
been fully seated. Checks at 1.2 Ohms so looks
good. Cleaned tip with eraser and reinstalled. It
does light during Synchronization rather than winding.
Powered by the local batteries, not the sync signal.
At the bottom of Fig 3 and Fig 4 you can see a raided section
at the center that's just over an inch long. It may be
that on earlier clocks a degree scale was attached here, but
on all the metal cases clocks I've seen on eBay, none has a
scale here. Nevertheless this hump can be used with the
pendulum to level the frame. The center of the pendulum
should move equally about this center marker for the
frame. If the frame is out of plumb by some small amount
the clock will stop.
Early January 2014 I installed a couple of printers and
needed to move a clock like Fig 3 above. Also added
Clock 1900GS synchronizer and 2 "D" cell battery
The battery holder includes some super caps to provide
higher current pulses to the clock for winding and
synchronization than you would get from a real No. 6 battery.
The synchronizer has a button at the top that you press
briefly at the top of the hour to tell it the current top of
Then every hour thereafter it pulses the synchronizer coil
in the clock.
Mounted the clock on wall and leveled it using a digital
level good to a fraction of a degree. And pressed the
But in a few days the clock was off by a couple of
minutes. That's because the miinute hand had been
manually turned to set the time and there was no longer a
relationship between the top of the hour and the notch in
the "heart" that the synchronizer needs to work.
That's to say that the minute hand needs to be in a specific
place on the shaft for the synchronizer to work.
To fix that I stopped the clock and manually rotated the
minute hand a little and manually activated the synchronizer
arm and keep moving the hour a little until I found the
notch in the "heart" and while holding the synchronizer in
moved the minute hand to the top of the hour. Then
aligned the hour hard to the exact hour mark. Then at
the top of the next hour started the pendulum.
To fix that I stopped the clock and
manually rotated the minute hand a little and manually
activated the synchronizer arm and keep moving the
hour a little until I found the notch in the "heart"
and while holding the synchronizer in moved the minute
hand to the top of the hour.
The hour hand has not yet been moved to be right on
Clock is stopped here waiting to restart the pendulum.
The wind button has been pressed to wind the spring.
PS the top screw is in a stud and has a large flat
head and is tight. It is tight enough that the
case does not swing.
I might put a couple of push pins in the lower
mounting holes just to be sure the case does not move,
but it will be gilding the Lilly.
Also at this time I manually held the wind button until it
stopped winding to be sure the spring was wound.
Then after an hour passed pressed the white synchronize
button and put the cover back on.
Now to watch and see if it keeps good time.
Idea For Improvement
Instead of using 4.5 volts (3 each AA batteries in the
synchronizer) it would be much better to use a high voltage
(like in a throwaway flash camera) in series with a carbon
resistor to get a much more lively and snappy
synchronization that would also be able to synchronize a
number of clocks connected in series.
I have a circuit coming from the UK that may be able to do
this. More to come . . .
The dial is close to 12"
diameter and the glass is about 11" dia. This is the
post 1938 dial that has the red lightning bolt and the red
lamp that flashes when the clock is synchronized on an hour
(+/- 2 minutes). The box is about 15" x 15" x 4.5".
This is what SWCC calls their
"F" movement. Some popular prior movements were the "A",
"B" and "C" that have a rotary motor made using 3 pair of
electromagnets. The "E" movement was for big clocks,
like in towers, posts or brackets. There was also a "C"
that used a vibrating winding motor. This first
vibrating motor drove the mainspring gear directly with a
pawl. The "F" movement drives an intermediate gear that
drives the mainspring gear. The "F" vibrating motor
assembly can be removed without disturbing the clock
gears. The "F 1/2L" is a heavy duty version for driving
large hands (up to 3 foot).
The "F" movement was used on many different SWCC clocks.
All that's needed to work with different beat pendulums is to
change the escapment gear to match the beat of the
pendulum. There are two styles of second hand, one is a
small hand placed on the shaft of the excapment wheel that's
between the center and 12 o'clock on the dial. Some with
a hole in the dial and some without the hole (Why?). The other
uses a gear on the escapment shaft to drive a regular seconds
hand that rotates about the center of the dial.
When used as a master or submaster clock switch contacts are
fitted so that once per turn of the escapment when the switch
closes, thus providing a 1 minute signal. This can be
used via external relays to drive slave clocks or a combined
day of the week and hour of the day bell program.
For an hour of the day only program the "F" movement can be
fitted with a 24 hour wheel holding a disk with notches for
the bell hours that works in conjunction with the minute hand
to ring the bell at any minute in the day, but with at least
10 minutes between bells.
The pivot point for the escape wheel is on a short arm held by
a screw thus allowing adjustment of the distance between the
anchor and escape wheel. I'm sure there are a number of
things that can be adjusted, some of which are not as obvious
as this one.
The distance between the pallet faces is 1.198".
The angle of the pallet faces is arc tangent (0.28/1.165) =
13.5 deg. The crutch angle shown in the photo was
measured on the photo and agrees pretty well with the computed
angle of 13.5 degrees.
In the photo the front of the clock is facing the camera but
the back of the pendulum is facing the camera. So you can see
that if the anchor was mirrored about the clock center line
the left pallet face would then be horizontal and the right
pallet would be vertical, which is correct for the Graham
The animated figure at http://www.abbeyclock.com/bbigrhm.html
shows the anchor with the pallet faces moving away from
horizontal and vertical by the swing of the pendulum.
But in the W.U. clocks the pallet facts are much further
away. Why is that?
As was the common practice in Telegraph equipment coils are
made in pairs. This clock uses one pair of vertical
coils in the hourly setting mechanism and another pair of
horizontal coils for the vibrating winding mechanism.
I'm still looking for patents to support why this was done.
DC resistance: 5.7
Ohms across resistor & coil
(Blue Gray Black Silver = 68 ohms) soldered across the coil
to reduce arcing of the switch contacts.
578976 Electric Clock Setting Mechanism, C.M. Crook, himself,
Mar 16, 1897,
584128 Synchronizing Clock, J.H. Gerry, SWCC, Jun 8, 1897, .
954714 Synchronizing Attachment for Clocks, P.E. Burns, Dey Time
Register Co., April 12, 1910, 368/52 ; 368/181
These dual coils use a solid iron core.
DC resistance: 12.6 Ohms
Inductance: not stable?
3 volts @ 230 ma will operate the synchronizer.
Must be done within a few seconds (minutes?) of top of the
The newer Self Winding Clocks
use a single coil that has a laminated core.
Experiments Feb 2014
In order to make a high voltage drive for a number of WU
Self Winding clocks testing what size HV capacitor with
what voltage to get snappy synchronizing action.
When using a DC power supply set to 1.5 volts (120
mA, 12.5 Ohms) the action is very slow.
Try 187 Ohm series resistor because that's the value of
the first high power one seen in the 100 to 999 Ohm bag.
At 20.8 V using the 187 Ohm series resistor directly on
the power supply it takes a few seconds to pull in (104
This is way too weak for reliable operation, but does give
some idea about the coil: 1.35 Volts, 13 Ohms.
Voltage drop = .12 A * 187 Ohms = 22.4 V plus 1.5 V drop
across coil = 24 Volts capacitor charge.
120 uF 330 V photo flash cap - fast charge - just works
220 uF 100 V - very weak (long charge time -poor quality
2200 uF 50 V - fast charge to 0 current - snappy sync 1
second hold w/187 Ohm res
60 Volts through 187 Ohms is a strong
50 Volts through 187 Ohms will synchronize plus or minus 2
minutes from top of the hour reliably.
40 V through 187 Ohms works
30 Volts through 187 Ohms is too weak to sync.
Video of the sync
The above video shows the sync working 2 minutes prior to
and 2 minutes past the top of the hour. But then it
appears to not work. I think this was caused by my
moving the clock hands relative to the heart shaped cam to
the point where they were out of sync.
I have a factory drawing that shows how to add a door bell
button to a clock so that it can be manually
synchronized. One of the two wires going to the button
is connected to the left battery positive terminal and the
other to the left Fahnestock clip. The Normally Open
push button (doorbell button) is connected at the far end of
the pair of wires. A short wire is connected from the
right Fahnestock clip to the right battery negative terminal.
The button is pressed one second before the top of the hour
and released on the hour.
Ideas for a Modern Synchronizer
Dec 2008 - The modern radio synchronized "atomic" clocks are
very convenient not only in terms of showing the correct time
but also handling the switch to and from daylight saving
time. It would be nice of the WU clocks could also do
that. Note that you can turn the minute hand forward
while the clock is running because there's a clutch in the
drive train. So an electromagnet, like the pair of coils
used in the winding mechanism or a more modern solenoid could
be used to pull a pawl over the minute hand gear that would
advance the hand one or more minutes for each
actuation. Also a photo sensor could be arranged to
sense when the minute hand was just prior to the top of the
hour by more minutes than the pawl can feed. i.e. sense
when to stop advancing the minute hand and get ready to use
the normal hand synchronization method.
Just like the "atomic" clocks you set the clock back one hour
be advancing it 23 hours.
Instead of using a low drive voltage it would be much better
to use a high voltage with a dropping resistor. A
possible source of HV is the power supply used in throw away
flash cameras. It's about 350 Volts which will work
well. But it may be more energy efficient to lower the
voltage to around 200 like was used when the clocks were in
A good source for the time and the DST information is the same
radio broadcast used by the "atomic" clocks, i.e. in the U.S.
This is really two different functions. The hourly
synchronization can be done by one device and that can drive
many clocks. The current limiting resistor needs to be
set for the total series string of clocks. The DST
advance and retard function needs to be a device that's added
to each clock.
Once the optical sensor is in the clock it can be used to
monitor the rate of the clock and give advice on setting the
pendulum adjusting nut. It can also detect if the
battery is low. This could be done by connecting a
couple of wires from the clock battery to the DST
circuit. This would both power the circuit and allow
directly measuring the battery voltage.
2824218 Automatic Control for Clocks, T. R. Gilliland,
Feb 18 1959, 455/204 ; 368/47; 968/511 -
2512462 Diversity System, Walter Lyons (RCA), Jun 20, 1950,
2661091 Apparatus for Weight Classification, N. G. MALONEY,
2695491 Clock Correcting Means Controlled by Radio Signals,
W.A. Kropp (IBM), Nov 30 1954, 368/47 ;
968/511 - WWV corrects a spring wound pendulum clock
2695492 Radio Time Signal Clock Correcting Means, Carl T.
Young (IBM), Nov 30, 1954, 368/47 ; 968/511 - WWV
corrects a spring wound pendulum clock
2699504 Automatic Tuning Device, Horace G. Miller (ITT), Jan
11, 1955, 334/24 ; 318/606; 331/177R; 331/35;
334/22; 455/162.1 - tunes RF transmitter
2734133 Electronic Control Circuit, J.J. Riley, - for
2745015 Automatic Tuner, J. Stillman (ITT), - RF amp tank
3063233 SECONDARY STANDARD TIMER, Donald
A. Bly (Hamilton Watch), Nov 13, 1962, 368/47 ;
368/187; 968/466; 968/520 -
decodes the tones from WWV
and WWVH and each second generates a pulse that advances
the clock (problem with missing pulses)
3217258 TIMING SYSTEM FOR SETTING CLOCKS
TO DISTORTED STANDARD PULSES, Arlin et al. - not
clear which radio signal it uses
3520128 AUTOMATIC TIME DISTRIBUTION
SYSTEM, Novikov et al.- for correcting a system of
5572488 Wristwatch paging receiver having
analog message display, (Seiko) - watch had disks that
revolve to show message through window
Battery was the wet battery chemistry that evolved into
the dry cell. And the first dry cell to become popular
was the No.
6. (never heard about No. 1 to No. 5). The early
Self Winding Clock Co. clocks had wooden cabinets with a shelf
to hold a pair of Leclanché Batteries. This clock
was designed to hold two No. 6 batteries which would power it
for more than a year. But it was a nuisance to have
someone carry around a long ladder and replace the batteries
each year. The No. 6 battery was designed to
replace one Leclanché jar.
I've heard from someone else that's running these clocks using
a couple of "D" batteries and they need to be changed after 2
years. Not bad at all.
[This is my guess] So at some
point a new cable was run to each clock from a central power
supply. Then the clocks built after central power was
common changed from open end terminals that would fit under
the thumb screws on the No. 6 battery to pin tip plugs, like
were common on headphones, to plug into a connector on the
end of the cable. That may explain why this clock has
two tip pin plugs on the right side and one on the
left. The other left connector is the open ended
terminal on the green wire which is also connected to the
frame ground. That would be correct to connect to a
ground screw on the cable connector. Since the Blue
wire goes between the two batteries, when connecting an
external 2 battery pack just connect to the two green
wires. Using tip plugs would make it easy for a man on
a tall ladder to connect or disconnect the wire, much better
than screw connections. But the electrical code
probably requires a screw on the safety ground (green) wire.
Fahnestock clips (Telegraph
Connectors) were supplied with the clock. The
hole in the clip is the correct size to fit the threaded
stud on a No. 6 battery. This would be a very good
thing if you were the guy that got to climb a tall
ladder to replace the batteries. Thanks to Larry K2JIA for
clearing that mystery.
Also above each battery pocket there's a rectangular piece
of insulation material attached to the frame and it's bowed
out a little so there's a small gap from top to bottom at
the center. What is this? my answer - If Fahnestock
clips are used on the two No, 6 batteries, then it would be
very easy for the clip on the negative terminal (the one
connected to the outer Zinc can) to scratch through the
frame paint and short out. Since the batteries are
wired in series the potential from a negative terminal to
ground might be 1.5 or 3.0 volts.
Do NOT do this
Whoever did this used two 6 Volt batteries for a total of 12
Volts! instead of using two No. 6 batteries (1.5 volts
each) for the correct 3 volts! A 400% overload is too
The eBay ad says "The rewinding function is not now
I doubt the seller will get their asking price after burning
up the motor coils.
I got this clock expecting the coils to be burned out, but
instead both winding switch springs have burned completely
through so there's no longer anything for the armature to
turn off. When powered from 3 volts the armature jumps
up and stays there.
New Winding Motor Contacts
5 July 2007 - New motor contacts arrived. The new
contacts are marked L and R and as you can see in the photo
at left they are mirror images of each
other. Made By:
P.O. Box 297
St. Germain, WI 54558.
The contacts marked "R" go on the front. It's easier
to see that the spiral contact marked "L" goes on the back
in close to the position shown at left with the flat in the
washer hole level and at the top. When looking at the
back of the movement the armature is on the Left and the
spiral points to the right.
Problem with Winding Motor Coil
Insulating Washers Rubbing on Rollers
operating switch and installing only one new contact pair
the motor did not work. After properly setting the
coil position the armature stuck when it was closest to the
coil. Running a piece of paper through the gap between
the armature and pole pieces on the coils confirmed they
were not hitting. But the roller was hitting the
insulating washer on the end of one of the coils. You
can see the shiny spots in the photo at the left where the
insulation is rubbing the roller. I've seen this same
problem on another Self Winding Clock and think the
insulation must be puffing up as it ages, maybe due to
A few light strokes with a Mototool grinder almost fixed
it. Still needed a little touch up with a file after
installing and adjusting the coils. Now the motor runs
fine on a single set of contacts.
To test the motor I remove the anchor so that the crutch rod
is out of the way, but more important there is no spring
tension. Then to check the strength of the motor stop
the escape wheel and watch the winding cam side of the
mainspring barrel. You can see that prior to stopping
the escape when the mainspring barrel rear pointing pin is
locked to the idler bar and the forward pointing pin on the
hourly winding cam. After two turns the pins are on
the opposite sides of the idler are indicating an almost
fully wound mainspring. In about 3/4 of a turn the
fixed stop causes the armature to stop in the up position
These tests were run using a couple of "D" batteries with
positive to the lower terminal with a red wire attached and
negative connected to the movement frame, bypassing the
hourly winding switch.
Hourly Winding Switch Problem
contact leaf is attached to a round post that is fixed to
it's base. To change the gap the leaf can be
bent. It's now working properly. This is
very different from the stack of 4 leaves uses on the sweep second "F" clock.
The red wire goes to the lower or positive terminal.
The upper wire goes to the winding contact.
When the battery is connected to a fully unwound mainspring
it does not wind since the winding cam is not being
driven. Grounding the negative battery wire to the
frame is the same a pressing the manual wind lever
switch. Let it wind until it stops then release the
manual wind power. Now as the clock runs down the
mainspring the winding cam is being positively driven and
when the high lobe comes up the winding motor will
start. During winding the mainspring cage will rotate
about one turn then the cam will be picked up and start to
turn which will shut off the winding.
Synchronizing Problem with 19"
3 Oct 2007 - After fitting a
door bell button wired to the sync terminals and the 3 volt
battery the clock jammed after the sync. It turns out
to be missing the thumb nut on the sync shaft and that
allowed the "C" arm to move forward slightly and engage the
gear in front of the setting cam, jamming the clock. I
have ordered a replacement and for now borrowed a nut from
another clock. The sync now works and the minute hand
points straight up. So it really does not matter where
the seconds arbor is in it's rotation since the minute hand
is centered at sync.
How Stiff do the Batteries Need
Starting about 11 June the rate changed
from about 1 second slow per day to slower and slower rates
on each successive day. Indicating some type of
problem. I'm guessing the two "D" cell batteries in
battery holders are not strong enough.
The minutes past the hour when winding occurs is controlled
by the cam and seems to be constant at :08 and :32. I
haven't come up with a simple solution to measure how long
it takes to wind, but manually timing is prone to a second
or two of error out of say 12 seconds.
I'm not yet sure of how weak batteries may effect
accuracy. So the first thing is to check on the
batteries. The setup shown has a Fluke 87 Digital
Multi Meter measuring the voltage across both batteries
(nominally 3 volts) and the MAX/MIN function is turned on so
each time the clock winds a new low is recorded. The
Open Circuit Voltage is now 2.985 and at the last wind the
minimum was 2.548 volts.
Have now changed the setup so that the winding current can
be recorded using the MAX/MIN function. The clock
would not self wind with the clip leads and series connected
amp meter. But when I press the manual wind button it
does wind. After that the peak recorded current was
296 ma although the average value I was seeing was around
The vibrating motor coil in my second S.W.C.C. Western Union
clock is about 5 Ohms which would draw 500 ma from 2.5 volts
or 600 ma from a fresh 3 Volt battery.
I thought about connecting a lab power supply to replace the
batteries, but on second thought don't want to take a chance
that the coil back EMF voltage spikes might blow out the
After disconnecting and reconnecting some of the wires, 15
Jun 2007, to do these tests the winding sounds
stronger. Maybe a poor electrical connection is
causing a problem? Need to get some Fahnestock clips.
After tracing out the circuit diagram it's clear that the 3
terminals on the left of the movement (looking at it on the
wall) are from top to bottom:
I so far have not seen anything to indicate that battery
polarity makes any difference, so the polarities could be
which is probably equivalent.
8 Oct 2007 - The clock has been sounding weak and
intermittent in it's winding and finally stopped because it
did not wind. I replaced the two 1900L battery adapters
with my home brew dual "D" No. 6 adapter that has both "D"
cells in one housing supplying 3 volts in the left pocket. I shorted the right side battery tip
plugs by pinching them using a brass #6 screw, a couple of
flat washers and a brass #6 thumb nut.
The winding sound is now much stronger than with the 1900L
Note that a single cell 1900L has about 0.22 ohms resistance
and a double "D" 1900L has about 0.12 Ohms. So when you
put one of each in series you have 0.34 Ohms or the more
common thing is to use two of the single "D" cell adapters the
total resistance is 0.44 Ohms.
But the home made double "D" adapter has only 0.15 Ohms
supplying the 3 volts. I think this is why it sounds
I don't know why the clock stopped winding. Both 1900L
adapters show good on a battery tester and their internal
resistance is the same as when I installed them.
One of the left battery wires has a "C" type terminal that
fits well under a thumb nut. The other three wire ends
all have tip plugs. Maybe I need to add some Fahnestock
In a repeating pattern of 24
minutes, then 36 minutes, then 24 minutes, etc. the clock
winds itself. The vibrating motor sounds like a small
air compressor. It has a sound that would indicate much
more powerful motor that what can be run from a couple of "D"
batteries. The motor would seem to be very
efficient. The original No. 6 batteries lasted for about
a year and a half.
5 June 2007 - checking winding times.
at 8 minutes past the hour the winding lasts about 8.2
at 44 minutes past the hour the winding lasts about
A pendulum clock has a period
that depends on the acceleration of gravity. That value
varies with Latitude (the earth is not a sphere) and
elevation. So even though a pendulum clock has been
setup to run perfectly at one location, if it's moved
somewhere else it's rate will need to be adjusted. It
turns out that the rate of an
atomic clock also depends on the acceleration of
gravity. This has implications on how accurately time
can be known. For example if there's an uncertainty in
the stability of gravity then this translates directly into an
uncertainty in the rate of a clock at that
location. An atomic clock in an Earth orbiting
satellite is in zero gravity so I expect that in not too many
years the location of the master clocks will be in satellites
rather than in metrology labs on Earth. Since GPS is THE
standard for time transfer most likely they will become the
master clocks and not the collection of atomic clocks now
It used to be that there was a physical "1 meter" bar that
was the "standard" for length. In a similar manner
there was a chemical cell used to define the Volt. But
these have been replaced with definitions based on the
second. The reason is that time can be measured much
much much much much much much much much much much much much
much much more accurately than anything else.
From the pivot to the tip the length is about 11". The
total swing is about 3/4" so the semi angle is about
ATAN(0.375 / 11) = 2 degrees.
I've been told that the pendulum in this clock is compensated
for both temperature and barometric pressure. I'm trying
to see how that's done. After some searching I'm
convinced that there's no barometric compensation and for use
in the U.S. probably unnecessary.
I've been told the rod is Invar (Wiki) which is
a metal designed for low thermal expansion. On the right
side battery support is a notice about adjusting the bob that
says this is a Type B pendulum. What is a Type A
pendulum, if you know please tell
spring is maybe 0.003" thick. You can see it just
to the left of the two Fahnestock Clips.
The hook at the very top of the pendulum that has a slit to
clear the spring and it's brass plates can also be seen.
Below the left rubber washer holding the clock mounting plate
to the frame is the switch for manually controlling
winding. The mounting "D" hole is at top center. A
small part of the anchor arbor (shaft) is visible in front of
the top center of the rear brass plate. The crutch is
attached to this shaft.
The weight of bob & rod about 1.5 pounds. Removed
bob to make drawing. Adjusting nut is 4-40 thread
Jan 8, 2009 - There is a limit to how accurately you can
adjust the pendulum nut. Maybe 1/4 or a little less of a
turn. Since stopping the pendulum and restarting it
changes the rate of the clock, i.e. you need to wait maybe a
few hours after starting the clock before making any
measurements on it's rate.
The Trick to making
fine adjustments to the rate
Set the pendulum nut so that the clock runs close to
the correct rate BUT is on the fast side. Then
use a candle to put a drop of wax on the pendulum
while it's moving. The added wax moves the
center of gravity down and slows the clock.
Tried this but the candle wax did not make enough
Pendulum Shipping Bolt Down
A very important feature of the
pendulum is that it's designed for shipping. First there
are a couple of holes front to back near the center of mass of
the bob and matching holes in the metal frame so that a screw
and wing nut can be used to bolt the bob to the frame.
There are also small long pockets next to each battery cup
designed to hold the screw and nut when the clock is
hung on a wall. At the top of the pendulum rod (see
photo immediately above) there is a "2 finger hook" that
attaches the pendulum to the suspension spring. The pins
at the top of the suspension spring run left to right and
since there's two of them the spring acts like the link in a
chain so that when the bob is bolted down the link allows the
rod to sit parallel to the frame.
I've read of many sad stories of people shipping pendulum
clocks where the bob became a wrecking ball. That won't
happen to this clock if the bolts are used! When they
are not, it's a mess.
Just to see what a 2 second
period (60 beats per minute) pendulum length would be:
enter T=2.0 sec, g= 9.80003 m/s*s and get 0.99295063933042
meter or 3.257712071294
Bob adjustment thread pitch results in 100 seconds in 24 hours
change for one turn. So:
If the clock was running perfectly the length would be as
If the clock was running 100 seconds slow per day then:
the period would be 1.0
sec * (86400 + 100) / 86400 = 1.001157
entering T=1.001157 sec and g= 9.80003 m/s*s
gives a length of 9.7957373456323"
or a change in length of 0.022628" or 44.19 TPI which
seems strange. standard thread pitches might be 32 or
Start with 40 TPI and g = 9.8 m/s*s for
100 seconds/day change.
nominal pendulum length (T=1, g=9.8) is 9.7731062962097"
or 248.23689992373 mm
adding 1/40" to length gives 9.7981062962097" gives a new
period of 1.0012782032604 sec
times 86400 seconds per day = 86510.4 or an increase of 110.4
seconds. Which is probably close enough.
The threads on a Brunell telegraph
sounder are 8-40, i.e. a #8 diameter but with 40 TPI. It
has a standard 4-40 thread for adjusting the height of the
bob. The spring at the top is about 0.003" thick.
A line drawn 9.773" below the top pin supporting the pendulum
goes through the center of the bob. The bob and rod up
to and including the hook that hangs from the bottom of the
spring weight about 1.5 pounds (+/- 0.5 pounds).
At the top of the rod there's a hook attached by a couple of
rivets. At the bottom of the rod there is a short 4-40
threaded part attached to the rod by a couple of rivets.
The brass bob adjusting nut supports the bob on it's top
surface which is a little below the 9.773" radius. The
use of rivets makes sense since Invar is hard to
machine. Invar doesn't expand with heat, but cutting
tools do so to drill you need a slow speed tool and plenty of
Using: T = 1 sec, M = 1.5 #, g = 9.80003 m/s*s, L =
gives: inertia moment or mass center (I) = 0.041926744315037
1023140 Escapement Regulator, F. Ecaubert, April 16, 1912,
368/171 ; 368/170; 368/202; 968/130 - vanes projecting from
wheel or bob.
Class Numbers: these are watch balance wheel class numbers,
not really for pendulum clocks, so 1023140 appears to have a
368 Horology: Time Measuring Systems or Devices/
368/170 - Oscillation or Reciprocating Means.Balance Wheel
368/171 - Oscillation or Reciprocating Means.Balance Wheel
Type..With Regulation...by Compensation
368/202 - Regulation Means.for Compensation
968/130 - Compensation of Mechanism for Stablizing
Frequency..for the effect of atmoshpere pressure
Searching first 968/130: only 3 patents
1350035 Compensating Balance Wheel, I. Povelsen, August 17,
1920, 368/171 ; 368/170; 368/202; 968/127; 968/130 - non
magnetic, extreme temperatures, low air resistance (marine
1683648 Escapement Controlling Mechanism, C.H. Beasley,
(Parkinson & W. & B. Cowan, Ltd.)
September 11, 1928, 368/134 ; 368/182; 368/202; 968/130 - T =
2 * PI * SQRT(L/G) basic pendulum formula. R =
Distance over which
the brake acts, pendulum Length.
Used for a gas regulator that compensates for pressure and
Searching 368/171 there are 106 patents.
203976 Compensation Balance, C.V. Woerd, (Waltham) May 21,
1878, 368/171 - geometry involved in placing a number of
weights around a balance wheel. Instead of the classic
two temperature compensation this is an all temperature
617852 Balance Escapement, A.R. Colburn, January 17, 1899
368/127 ; 368/170; 368/171; 968/105 - all older patents in
this class are for balance wheels, most like 203976 have a
number of weights on the outside diameter in the form of
895172 Compensating Controller for Timepieces, F. Ecaubert,
August 4, 1908, 368/171 ; 368/202 - same inventor as 1023140
965503 Compensating Escapement Regulator, F. Ecaubert, July
26, 1910, 368/171 ; 368/170 - the strap spring that supports a
pendulum is deflected by an mechanism to change the effective
length for temperature compensation.
965504 Compensating Escapement Regulator, F. Ecaubert, July
26, 1910, 368/171 ; 368/170; 368/202 - for use on
400-day clock where the pendulum acts in torsion, i.e.
965505 Compensating Balance Wheel, F. Ecaubert, July 26, 1910,
368/171 ; 368/202 -
965506 Compensating Balance for Timepieces, F. Ecaubert,
July 26, 1910, 368/171 ; 368/202
***965507 Escapement Regulator, F. Ecaubert, July 26, 1910,
368/182 - Both Temperature & Atmospheric compensation of
965508 Balance Wheel for Timepieces, F. Ecaubert, July 26,
1910, 368/171 ; 368/202
1048072 Balance for Clocks and the Like, W.P. Hinkleman,
December 24, 1912, 368/171 ; 368/170; 968/103; 968/99 -claims
to replace hair spring speed regulator and pendulum.
Part 1 is in The Observatory # 103 pg 384 and part 2 in The
Observatory #104 pg 435. This is the publication of the
Royal Astronomy Society and the Liverpool Astronomical
Society. Volume VIII is for 1885.
The Sidereal Clock at the Greenwich observatory when GMT time
started was made by Dent who made the Meridian
Instrument. They were planning on using a Mercury
bob, but Dent's Zinc and Steel bob worked so well the mercury
bob was not used. The bob in the SWCC clock appears to
be a zinc alloy? But the barometric compensation used in
this clock was based on floating one end of a lever arm in the
mercury pool at the base of a barometer and the other end of
the lever arm moved a magnet up and down just below the bottom
of the pendulum which has a couple of bar magnets mounted on
either side. Thus when the air density is higher making
the pendulum lighter an added downward force causes the
pendulum to maintain it's weight. GMT started 1 Jan
1885. It causes the astronomers to set their clocks
forward by 12 hours.
John Harrison of "Finding the Longitude" fame invented the
Gridiron pendulum (Wiki)
which uses the differences in thermal expansion of steel and
brass (didn't have zinc then) to get temperature
on pendulum clocks says the errors come from: temperature,
atmospheric drag and local gravity.
But I've also read the the effect of atmospheric pressure is
to change the air density, which changes the weight of the bob
since the bob is floating in the air. In a vacuum the
bob is significantly heavier than it is when the air is
showing the atmospheric pressure and running rate of a
Synchronome clock clearly shows that the clock runs fast at
low pressures and slower at higher pressures. This
supports the idea that no air reduces air friction to zero
allowing the clock to run faster. And also supports the
idea that no air provides no buoyancy so the bob is
heavier, just as if gravity was increased. From the
formula for the period you can see that more gravity
causes the period to decrease, or the clock runs faster in a
If the drive power to the pendulum is near constant then less
friction or more gravity will cause the swing to get
larger. But as the semi angle gets larger so does the
cycloid error. So one way of getting barometric
compensation is to have a drive mechanism that gives the
pendulum the same drive power and somehow get the cycloid
error to balance the barometric error. Testing this
would require a way to measure the semi angle along with the
barometric pressure in a controlled way and plotting rate vs.
semi angle as the pressure is changed.
Astronomical Regulator Clock at the UK National Maritime
Museum has "concentric tubular zinc and steel temperature
compensated pendulum with cylindrical , matt-black painted
brass cased bob" 1885 used till 1937.
508530 Mercurial compensation Pendulum, S. Riefler, November
14, 1893, 368/182
508760 Pendulum Escapement, S. Riefler, November 14, 1893,
368/134 ; 368/179; 968/98
Class 368/182 = Horology/Oscillating or Reciprocating
Means.Pendulum type..With regulation...By thermal compensation
so for barometric pressure it should be 368/181 =
Horology/Oscillating or Reciprocating Means.Pendulum
since it's regulation but not temperature.
In the book Watch & Clockmakers Handbook (1881) it
suggests that by proper design Pendulum error (circle vs.
cycloid) can be used to correct barometric error.
I've received two opinions that I respect and both have said
that this clock does NOT have barometric correction.
Also that in the U.S. there almost no need for it since
barometers in most places don't change that much.
In Chapter 3 "The Pendulum" of
The Science of Clocks and Watches" ISBN 0950962139 Fig 3.8
shows an Invar rod and a lead bob where there is a short
steel tube lifting the bob. The idea being the tube
compensates the steel suspension spring holding the
rod. If the tube is made a little long, then it can be
trimmed to get the compensation perfect. It also
mentions there are problems if threads are used at the top
of an Invar rod, but this clock uses a rectangular shaped
rod and a pin for attachment of the spring suspension.
The book suggests type metal (lead 70, tin 18, antimony 10
& copper 2%) is harder. Cast iron is very
stable. The 3rd edition of the book has added
information on the instability of some different Invar
blends. Other possible rod materials are Zerodur by
Schotts, ULE, etc.
This was the SWCC offering around 1908
There must be more pendulums
9.77" len to c.g.
* SWCC clock movement s/n39580
This patent had long since run
out when Western Union took over S.W.C.C. and started offering
the Naval Observatory time service. So no patents were
954714 Synchronizing Attachment for Clocks, P.E. Burns, Dey
Time Register Co., April 12, 1910, 368/52 ; 368/181
The regulator nut on these 120 beat clocks is one turn for 100
seconds per day. I haven't yet figured out the knurling
pitch to see what one knurl of change is in time. But
it's hard to make a fractional turn of a know amount since
there's no calibration. If you got the nut to within
1/10 turn then the clock might be off by 10 seconds per
day. So an hourly synchronization would keep on within a
An error of 100 seconds in a day translates to an error of 4
seconds in an hour so the regulating nut only needs to be set
to a quarter turn if the clock has hourly synchronization to
be accurate to 1 second..
A little Vaseline (petroleum
jelly) in the rectangular window where the winding motor moves
once a year. Use a tooth pick.
Step 0 Mounting
Figure 2. On the back of the frame at the top center
there's a big hole with a slot pointing upwards. The
idea is you install a screw with a large head into a
stud. Then the clock can be hung on the screw without
any tools. After it's plumbed, or better after the beats
are set equal, you use the lower left and right mounting
holes to anchor the clock to the wall. On the back of
the frame these three mounting locations protrude slightly
from the plane of the square frame edge. The idea is
that the frame is only fixed at three points. That's way
my frame is not flat against the wall.
If you look down at the top center when the clock's mounted on
the wall with the cover installed there's a hole about 1/4"
diameter. This is composed of a groove in the front of
the frame and a notch in the cover. This is where the
synchronizing and/or DC power cable enters the clock.
Step 1 Set the Beat
The older instructions say to just have the pendulum swinging
over the center of the frame. But that's really not as
good as tilting the frame so the the time between beats is
equal. If a photo detector is placed so that it's
interrupted by the pendulum you can get a very good measure of
the period, but not the length of each beat. A
microphone would hear each beat, as does your ear, but even
when properly adjusted the beats may sound different so I
don't think a microphone is a good way. The best way is
probably some type of sensor (or sensors) activated by the
anchor or escapement wheel. (contact mike that's part of an
I taped a strip of paper to the frame, but a piece of
3x5 card stock would have been better so that the top edge
could be just below the bob when it's at dead
center. Taped a narrow pointer made of paper to
approximately the center of the bob. Manually move
the bob slowly back and forth listening for the click as
the pallets strike the escapement wheel. Mark the
left and right points. Make a new mark half way
between these (in my case this was less than a half
inch). Note the total swing is much greater than
these two points.
Now rotate the frame to bring the pointer to the center
This method depends on looking at each of the pallets in
relation to the teeth on the escapement wheel.
Something my eyes are not up to.
by Bryan Mumford has a Beat
Error Mode that works by measuring the time between
beats. Just rotate the frame until the error is
zero. Since the Microset is a small hand held device
it's easy to bring it to the clock.
Immediatelyafter setting the frame small brads were driven
into the lower two holes. One on the left side of the
left hole and one on the right side of the right hole.
Then the mounting hex head screw (into a stud) was snugged
up. But the frame can wobble back and forth. I
don't think my wall is that uneven but do think there's some
projection on the back of the clock. Maybe I'm supposed
to gouge a hole for it?
I've also installed a couple of Radio Shack 270-403A single
"D" battery holders and wired up the clock so that the cover
can be installed. I needed to change the minute hand
since it was off 90 degrees. And have manually
synchronized to clock by squeezing between the top and bottom
of the electromagnet at 1 second to the hour and releasing at
exactly the hour.
Then installed the cover. Now we'll see how it's
running. With the cover off and before setting the beat
it was running about 1 to 1.5 minutes slow per day.
3 Oct 2007 - In The
Science of Clocks & Watches by Rawlings,
he says an off beat clock will keep the time as well as one on
beat. But an off beat clock will stop sooner. So
it may take more power to run the off beat clock. If you
have data let me know.
Set the Time
The minute hand can be moved forward to set the time, but on
my clock after doing that the minute hand does not seem to
advance. So I used the lever switch to manually wind the
clock and the shaft made a little over one turn. After
that the minute hand is moving normally. So maybe if
you're going to stop the clock you do it just prior to a wind
so that it can be would after setting the minute hand when
Another possibility is that this is a problem related to why
my clock winds twice per hour?
Step 2 Adjust the bob
To adjust this clock you need to stop the clock, turn the
adjusting wheel in the pendulum ( Left = slower, R = faster)
and restart the clock. After adjusting let the
clock run for at least a day, maybe longer before making
another adjustment. Note it can take a few hours for a
pendulum to stabilize so you can not check the rate until
Since it can take hours for the pendulum to stabilize after
being restarted it would be advantageous to allow for
adjusting the period while the clock was running. The
stabilization time would be much shorter. Self Winding
Clock Co. has a patent to do just that. 393638
Pendulum Regulator for Clocks, J.H. Gerry, 27, Nov 1888,
368/181, 368/271 - but so far I've never seen one. It
works at the top of the pendulum suspension by moving it up or
down changing the length of the pendulum.
I wonder if tilting the clock can be used for fine adjustment?
ans. No. The frame should be adjusted so that the time
between beats is equal.
Also, since this clock does not have an official second hand,
how do you reset the seconds? Ans: No need since as
accurately as it can be read is some fraction of a minute.
19 May 2007 7:43 am - In order to check the rate the dial is
back on. Like the Standard
Electric Time Slave Clock, you can turn the minute hand
(forward only) to set the time. The minute hand moves in
1/120 minute steps which for all practical purposes is an
analog movement. But to be technical it's really a
digital movement. With the dial installed I can't see
the second hand so it will take longer to check the
rate. Well maybe not. The minute hand is the same
width as the wide minute mark used at each 5 minutes of time
(the hour marks), so by watching for good alignment you can
recognize to at least a couple of seconds, maybe better, when
it's the top of a 5 minute minute interval. At the top
of the 8:00 hour it was spot on.
21 May 2007 - 9 pm Using two "D" cells for power, one in each
battery pcoket, have synchronization at 9 pm. and outer cover
22 May 2007 - 7 am about 1 minute slow in 10 hours, or 2.4
min/day. But this may be part of the setteling process,
need more time.
23 May 2007 - 8 am slow about 3 minutes, which is a rate of 2
minutes/day. waiting for literature that has the cal
factor for the pendulum adjusting nut.
24 May 2007 - 7am slow about 6:20 in 58 hrs or -2:37/day
24 May 2007 - 9 pm slow 8:00 in 62 hrs or -3:06 /day
<- ? accuracy of delta
25 May 2007 - 8:30 pm slow 9.5 min @ 95.5 hrs or 2:23 per
day The Clock on the right is a slave that was just set
and the 19" wide box on the bottom is a Cesium standard
running 3E-14 slow. 3
On the right side battery can it says:
Regulating Directions 120 Beat Type B Pendulum If clock gains turn
regulating nut to the left. If clock looses turn
regulating nut to the right. One turn of regulating
nut changes rate 100 seconds in 24 hours either fast or
So, what is a Type A and Type B pendulum? If you know please tell me.
So one and a half turns to the right minus a little. Done 9:15
pm. Both batteries check good. Cover back on.
26 May 2007 7:15 am - Clock was stopped. The jiggling
caused by taking the cover off triggered the self
winding. There may be a problem with the switch that
activates self winding. It winds in a pattern of 24, 36,
24 minutes between winds but the cam only has one lobe so it
should wind once per hour. When the hands are manually
turned (clockwise only) the relation with when winding occurs
27 May 2007 7:45am - Clock is about 45 seconds slow, but
that's about where it was last night. Hard to tell the
rate this soon. It's winding at 10 and 45 minutes past
27 May 2007 9:45 pm about 1 minute slow in 38 hours or 38
28 May 2007 8:45 am about 1:15 slow in 49 hr or 37 sec/day
28 May 2007 4:30 pm about 1:30 slow in 56.75 hr or about
38 sec/day slow or 0.38 turn to Right.
28 May 2007 7:30 pm restarted after making some measurements
29 May 2007 6:40 am - too close to right on to tell
anything. (winding at :08 and :44 minutes past the hour)
30 May 2007 7:30 am too close to right on to tell. 36 hrs
<10 sec so less than 6 sec/day
30 May 2007 3:00 pm - restarted clock w/manual sync).
For some unknown reason it stopped while having it's picture
taken (see above bob photos).
31 May 2007 6:00 am - maybe 10 seconds fast in 15 hrs.
The winding is now at :08 and :32 minutes past the hour.
Before it was at :08 and :44, so it looks like the :08 past
the hour is the real hourly cam and the :32 or :44 minutes
past the hour is a bug.
2 Jun 2007 7:00 am - within a few seconds after 64 hours <
4 Jun 2007 7:00 pm - Looks to be right on the money<3 sec
in 124 hrs or <.5 sec/day
9 Jun 2007 9:00 pm - Within 5 seconds in 246 hours or
better than 0.5 sec/day - It's a lot easier to set this clock
than to set the quartz clock driver for the Standard Electric Time Co. slave clock
which is now overe 1 minute fast.
10 Jun 2007 9:00 pm - running 11 seconds slow in 270 hours
or 0.97 sec/day slow. - new measurement method. First look at
the reference clock seconds count and listen to this cock's
beat. While continuing to count the time of the
reference clock, keep counting until this clock has the minute
hand pointing straight up. In this case the count was
past the hour so this clock is slow by the count. If the
minute hand was straight up before the count of 60 the clock
would have been fast. This method is much more
accurate than trying to guess the seconds by "reading" the
11 Jun 2007 9:00 pm - 22 seconds slow in 294 hrs 1.8 sec/day
12 Jun 2007 10:00pm - 29 seconds slow in 319 hours or 2.2
sec/day - appears to be slowing down?
14 Jun 2007 10:10 pm exactly 1 minute slow in 367 hrs or 3.9
sec per day - is slowing down & accelerating, battery or
the warm weather?
18 Jun 2007 6:00 pm - clock reads 6:00:00 actual time is
6:01:38, clock is slow by 1:38 in 459 hrs, or 5.1
sec/day. Still slowing down. I was expecting the
rate to remain constant. It's been hot the last week or
so, maybe that's related.
19 Jun 2007 11:30 pm clock reads 11:30 , actual time is
11:31:52 1:52 slow in 489.5 hr, or 5.5 sec/day slow.
20 Jun 2007 3:00 pm clock is 2:00 min slow in 505 hrs, or 5.7
28 Jun 2007 3:00 pm - slow 3.00 minutes in 673 hrs or 6.42
sec/day (IMP2 driving the SET slave clock is 3:44 min fast,
poorer than the pendulum)
15 July 2007 9:00 am - slow 4 minutes in 1075 hrs or 5
30 Jly 2006 - 34 sec slow - I forget if it was changed between
15 & 30 July?, don't think so. Wonder if there's
coupling to the 37SS across the room?
10 Sep 2007 16:45 - 27 sec slow measuring from 30 July it's
been 42 days and the time has speeded up 7 seconds, or
0.16 seconds/day. Pretty good.
The adjusting nut is 100
seconds per turn. It's diameter is about 0.684" or the
circumference is about 2.15". So to get a 5 second/day
change the circumference needs to be moved about 1/20th of a
turn or 0.1" to the right. This is approaching what
can be done with the adjusting nut.
Bent winding contacts up slightly so point does not
Installed Ken's battery adapters
moved adj nut right 0.1"
manual synchronized at 10:00am - non effective, minute
hand wrong 1/4 hour, reset minute hand.
Jan 2010 - To make fine rate adjustments you can NOT stop
the clock to make the adjustment. So the procedure is
to first set the rate so it's a little fast, then use a
candle to drip wax on the bob to slow it down. Tried
that didn't work, not enough change after a few drops, maybe
need to have hundreds of drops, but the flame is a problem.
Synchronization only sets Minute hand, not seconds
There is a provision on other
SWCC clocks for the synchronizer to set both the minute and
seconds hands. But on the square metal cased clocks
without a second hand the synchronizer only sets the minute
Minute hand square shaft
Once the knurled nut is
loosened the minute hand will point to 6:00 and so should be
put back on pointing to six if that's the position when
removed. To check it before the knurled nut is
tightened look behind the dial (a flashlight helps) and
rotate the minute hand slowly clockwise and see at which 1/4
hour the pin pushes the synchronizer lock to the
right. If that happens at 12:00 then the minute hand
is on correctly, otherwise note how many 1/4 hours and which
way to move it and reinstall. If this is done
improperly the synchronizer will not work. Also the
time of the hourly winding will be different.
Now winding at 37 minutes past the hour.
The two "D" cells that were installed a couple of months ago
test in the middle of the green, i.e. like a new battery.
Regulating large square metal case clock
a couple of rough adjustments
29 sep 2007 sync at 3:00 pm
1 Oct 2007 - clock slow by 4-1/2 min or 135 seconds per day.
one turn on nut right -
12 Jan 2010 - will try the candle wax method on this
clock. It's been running for a couple (+) of years on
the same home made two "D" cell battery adapter.
12 Jan 2010 set at 6:40 am
19 Jan 2010 clock 4:52 actual time 4:45 so 7 minutes fast in
7 days 10 hrs 5 min 6.55E-4 rate
22 Jan 2010 - reset clock to 10 am and added a couple of
drops of red candle wax to pendulum while it was
running. Done from the left side.
23 Jan 2010 - actual time: 12:43, clock time 12:44, i.e. 1
minute fast after 1 day + 2h43m, 6.24E-4 rate (added much
24 Jan 2010 - acutal time 5:42 pm, clock time 5:44 pm, i.e.
2 min fast, still gaining? Wait another day or so.
31 Jan 2010 - acutal time 8:30 pm, clock time 8:40, i.e. 10
min fast since 23 Jan 12:43 pm
when it was 1 minute fast, gained 9
minutes in 8d 7h 47m (11987m) for a rate of +7.5E4 - bummer
it's not getting slower.
The Time Telegraph Co patents: 274324
Circuit For Electric Clocks, V Himmer, TTC, Mar 20 1883,
Electric Clock, V Himmer, TTC, Mar 20 1883, 368/160 ; 235/131R 305632
Secondary Electric Tower Clock, C.H. Pond, TTC, Sep 23, 1884,
368/59 ; 235/131R
C.H. Pond patent:
Electro Mechanical Clock, C.H. Pond, November 25, 1884, 368/49 Pond
Wind - the early patents above were prior to the
founding of the Self Winding Clock Co.
Self Winding Clock Co. patents: 362902
Circuit Controller for Self Winding Clocks, C.H. Pond, May 10,
1877, 368/149 411168
Gong striking mechanism for synchronized clocks, C.H. Pond,
Self Winding Clock Co, Sept 17, 1889 - 584128
Synchronizing Clock, 8-Jun-1897, 368/60 ; 368/187 - 611822
Electric Time Switch, 4 Oct
1898, - 307/141 ; 185/40B; 200/38DA; 368/149
Although this patent is mainly
concerned with controlling arc lights it does include some
features of the winding motor and the "knock away" part of
the winding motor control switch. - This is the patent date
that appears on most of the "F" movements.
W Moore, Aug 2, 1910, 368/150;
368/124 - This is a self winding clock, but long after the
611038 patent, why was this one granted?
I found it because of a patent citation on 2531121,
Mechanical time fuses.
American Clocks, Vol 2, 1995,
Tran Duy-Ly, ISBN10 0930163443 - has a Chapter of
information from Self Winding Clock Co. advertisements and
installation brochures up to about 1910. No information
on Western Union clocks. Mainly aimed at
Science of Clocks & Watches, 1993, A.L. Rawlings,
3rd Ed, ISBN10 0950962139 - Third edition has new comments by
a number of B.H.I. members. General book about precision
pendulums like used in observatories. Not directly
related to SWCC clocks. Aimed at precision clock
design. The first edition was done in 1944 and the
second in 1948 were both all the work of Rawlings so the
comment of page 56 was his thinking around 1948
"Astronomers are asking for
clocks that can be relied on to vary much less than one
second a month or even less than one second a year, so that
variations in the rate of the earth's rotation, if any, may
be detected and measured."
is a perspective into the thinking of that time.
Clock Pendulums, 2004, R.J. Matthys, ISBN 0198529716
- a close experimental look at what effects the stability of
the pendulum. A huge amount of work has gone into
looking at various questions experimentally. But the key
questions may not have been asked. For example when
looking at the bob many shapes were considered based on had
been proposed by others, but when looking at the rod only
circular was considered. A rectangular rod was not
mentioned, yet the SWCC clock uses a rectangular Invar
rod. A good thing about the book is that it puts a
number on the various errors so that you can go after the
larger ones first instead of wasting time fixing a small error
to no advantage. No mention of composite carbon fiber
Modern Clock - A study of Time Keeping Mechanism; It's
Construction, Regulation and Repair by Ward L.
Goodrich, 1984, ISBN 0-930 163-23-0 - Some details on
Information on the "A", "C" and "F" Self Winding Clock
Co. movements and their adjustment. The wording and
methods are different from those in the "F" manual,
haven't figured out which is newer. First ed. of
Modern Clock was 1905, second ed. was1950, so this info
may be more up to date than that of the "F" manual.
Also a comment about slave clocks not working in general
and how they keep track of their own errors. The
main error is either failing to advance or advancing too
far during the instant when the advance is supposed to
occur. The only way around the problem was patented
by Standard Electric Time for their tower clock and uses a
worm gear that can not be turned backwards.
Inpulse Timepiece, W.E. Maxwell, May 20, 1941 - patent
2242654 issued the same day.
Low cost Battery Adapter
Hourly Time Synchronizer that's "Atomic" accurate - the
watch crystal units are far from accurate.
Help for equalizing the beat when installing
monitor some key clock parameters
Help for setting the bob height
Precision pendulum position sensor - Instead of just
getting an on/off signal once per period, get the
pendulum position in real time.
The above ideas are not totally independent. If
interested let me know.