[time-nuts] Antique pendulum clocks

[Ben Bradley]

You may be interested in a thread here earlier this year titled
"Absolute time accuracy pre-Cesium?" starting March 25. Also, look for
references to John Harrison in the archives. There's a video showing
several of his clocks running with the grasshopper escapement, and one
of his long clocks being taken apart.
http://lists.febo.com/pipermail/time-nuts_lists.febo.com/

On Wed, Nov 20, 2019 at 8:00 PM Philip Gladstone
<pjsg-timenuts at nospam.gladstonefamily.net> wrote:
>
> I've started to monitor the individual ticks on a grandfather clock from
> the 1790s. Essentially I timestamp whenever the pendulum breaks/restores a
> light beam.
>
> The data that I get is surprising in that the pendulum swing varies
> according to the position of the hands on the clock. It appears that the
> amplitude of the swing depends on the driving force imparted by the
> escapement. Since the second hand is not counterweighted, there is slightly
> more energy available to drive the escapement during the first half of each
> minute and slightly less in the second half. There is much bigger effect at
> the end of each hour when the mechanism has to move a lever to trigger the
> strike mechanism. This 'end of hour' effect changes the pendulum swing
> enough so that the period is noticeably affected (maybe by 300ppm)
>
> Anyway, my google-fu did not reveal anybody else interested in this
> stuff... Anybody here interested?
>
> Philip
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.