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 land.
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 convenient.
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
compensation. The best clock of this type she has seen lost 15
seconds after 70 of running (without synchronization).
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 involvement.
The USNO started
using the Photographic Zenith Tube about 1934 (article in Popular Astronomy Feb 1942).
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
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
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.
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
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 escapement.
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,
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 hour.
The newer Self Winding Clocks use a
single coil that has a laminated core.
I have a factory drawing that shows how to add a door bell botton 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
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. WWVB.
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
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 resistance welder
2745015 Automatic Tuner, J. Stillman (ITT), - RF amp tank tuning
3063233 SECONDARY STANDARD TIMER, Donald A.
Bly (Hamilton Watch), Nov 13, 1962, 368/47 ; 368/187; 968/466;
decodes the tones from WWV and WWVH and
each second generates a pulse that advances the clock (problem with
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
5572488 Wristwatch paging receiver having analog
message display, (Seiko) - watch had disks that revolve to show message
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.
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)
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
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 Fahenstock 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
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 much.
The eBay ad says "The rewinding function is not now working".
I doubt the seller will get their asking price after burning up the
I got this clock expecting the coils to be burned out, but instead both
winding switch springs have burned completly 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
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
Washeres Rubbing on Rollers
non 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 moisture
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
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 drawing current.
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
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.
Syncronizing Problem with 19" Clock
3 Oct 2007 - After fitting a door bell
button wired to the sync
terminals and the 3 volt battry 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 to Be?
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
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 150 ma.
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 power supply.
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
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 swapped to:
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 sould is now much stronger than with the 1900L battery
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 soulds stronger.
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 Clips?
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 seconds.
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 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
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 used.
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
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 me.
Suspension spring is maybe 0.003"
thick. You can see it just to the left of the two Fahnestock
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 munting 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.
Weight 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 accuratly 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.
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.
Pendulum Shipping Bolt Down
A very important feature of the pendulum is that it's
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) peldulum length would be:
enter T=2.0 sec, g= 9.80003 m/s*s and get 0.99295063933042 meter or
Bob anjustment 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 given above.
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
or a change in length of 0.022628" or 44.19 TPI which seems
strange. standard thread pitches might be 32 or 40.
9.8 m/s*s for 100 seconds/day change.
nominal pendulum length (T=1, g=9.8) is 9.7731062962097" or
adding 1/40" to length gives 9.7981062962097" gives a new period of
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
rivits. At the bottom of the rod there is a short 4-40 threaded
part attached to the rod by a couple of rivits. 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 rivits makes sense since
Invar is hard to machine. Invar doesn't expand when 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 = 9.773109287977"
gives: inertia moment or mass center (I) = 0.041926744315037
1023140 Excapment 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 wrong classification.
368 Horology: Time Measuring Systems or Devices/
368/170 - Oscillation or Reciprocating Means.Balance Wheel Type..With
368/171 - Oscillation or Reciprocating Means.Balance Wheel Type..With
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 chronometers).
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 = D/L: Resistance, Distance over which the brake acts,
pendulum Length. Used for
a gas regulator that compensates for pressure and temperature.
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 compensation.
617852 Balance Escapment, 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 screws.
895172 Compensating Controller for Timepieces, F. Ecaubert, August 4,
1908, 368/171 ; 368/202 - same inventor as 1023140 above
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
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. rotates.
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 pendulum
965508 Balance Wheel for Timepieces, F. Ecaubert, July 26, 1910, 368/171
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
The Siderial Clock at the Gweenwich observatory when GMT time started
was made by Dent who made the Meridian Instrument.
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 froce causes the pendulum to maintain it's
weight. GMT started 1 Jan 1885. It causes the astronomeres
to set their clocks forward by 12 hours.
John Harrison of "Finding the Longitude" fame invented the Gridiron
of steel and brass
(didn't have zinc then) to get temperature compensation.
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
air friction to zero allowing the clock to run faster.
And also supports the idea that no air provides no buoyancy so
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 vacuum.
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
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 Pendumum, S. Riefler, November 14, 1893,
508760 Pendulum Excapement, S. Riefler, November 14, 1893, 368/134 ;
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 type..With regulation
since it's regulation but not temperature.
In the book Watch & Clockmakers Handbook (1881) it suggests that by
design Pendulum error (circle vs. cycloid) can be used to correct
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.
1.5# lead or
* 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 required.
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 second.
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 (petrolum 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 why 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.
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 stick
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 position.
This method depends on looking at each of the pallets in relation
to the teeth on the escapment wheel. Something my eyes are not up
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.
Imediatly after 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 you're done.
Another possiblity 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 stablize so you can not check the
rate until that's happened.
Since it can take hours for the pendulum to stablize after
being restarted it would be advantageous to allow for adjusting the
period while the clock was running. The stablization 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.
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
Also, since this clock does not have an official second hand, how do
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
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 installed.
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
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 Clocks photo.
On the right side battery can it says:
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 slow.
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 is changed.
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 the hour.
27 May 2007 9:45 pm about 1 minute slow in 38 hours or 38 sec/day slow
28 May 2007 8:45 am about 1:15 slow in 49 hr or 37 sec/day slow
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
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 < 1.1
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
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 minute hand.
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 sec/day
28 Jun 2007 3:00 pm - slow 3.00 minutes in 673 hrs or 6.42 sec/day
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 sec/day.
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 cause winding.
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
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 hand.
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
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 more wax)
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, 368/184 274325
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 ;
C.H. Pond patent:
Electro Mechanical Clock, C.H. Pond, November 25, 1884, 368/49 Pond
Self 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,
Synchronizing Clock, 8-Jun-1897, 368/60 ; 368/187 - 611822
Electric Time Switch, 4 Oct 1898,
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
Vol 2, 1995, Tran
Duy-Ly, ISBN10 0930163443 - has a Chapter of information from
Self Winding Clock Co. advertizements and
installation brochures up to about 1910. No information on
Western Union clocks. Mainly aimed at collectors.
The 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
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.
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 for rods.
The 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 escapment design.
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.
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
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.