 
400-day or Anniversary Clocks
These clocks are designed to run for 400-days on one winding. This
means that there is very little power to drive the pendulum and so it is
imperative to keep these clocks in first-class condition and to set them up
correctly. The large old ones are good time-keepers but the smaller,
mechanical, modern ones are not quite as good.
Place these clocks on a level and firm surface where they will not be moved
nor jarred.
The later examples of these clocks (illustrated above) have a four ball
pendulum, the bottom of which hangs within a small brass cup fixed to the
base. The levelling feet must be turned until the pendulum is centered
within this cup and not touching it.
Winding
Wind the clock fully using a well-fitting key ( a slipping key could ruin the
clock). The clock will then run for a year although, it is
recommended for better time-keeping to wind every three months.
Starting the clock
With the clock wound and levelled as described above, give the pendulum a
half to 3/4 turn and let it go and the clock will start if it is in good
condition. if the pendulum is turned too far, you will put a permanent
twist into the fine wire suspension and it will have to be replaced. If
you move the top of the suspension, the clock will be put out of beat and it
will require the attention of the clock repairer to correct it.
Transporting the clock
Later clocks had some means for locking the pendulum for transporting the
clock. As there were so many ways devised in which this can be done
it would be wise to ask your clock repairer how to do it. Earlier 400-day
clocks had no means of locking the pendulum so that it has to be lifted
carefully off the bottom of the suspension before the clock is moved.
Regulating
The 4-ball pendulum clocks have a knurled disc at the top of the pendulum for
regulation (see illustration above). Hold the pendulum firmly while
turning this disc to - or S to make the clock go slower or to + or F to make it
go faster. Older disc pendulum clocks have a horizontal adjusting screw
for regulation.
Any regulation should only be done after the clock has been running for at
least an hour and then by no more than 1/16 of a turn at a time. They take
weeks to adjust to good time-keeping, so be patient.
© John Locke 1996-2004
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