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Some further comments on chronometers, for what it is worth.

In my experience, the rate of quartz watches and clocks would appear to be
dependent on the battery voltage. I have observed marked change in the
rates of quartz watches when I change batteries. Quartz watches would
appear to use 32 khz crystals which are not cut for temperature
compensation, as crystals used in radio frequency work are. Wrist watches
depend on the wearer providing a relatively stable temperature environment.
Quartz chronometers, by virtue of their much larger size, would be able to
provide a voltage controlled power source using a large battery and to use
a crystal cut for temperature compensation.

Hamilton mechanical chronometers seemed to have used the Ulysse Nardin
chronometer from Switzerland as their starting point when they started
making chronometers in WWII. They were not a copy of the Thomas Mercer
English chronometer. The Hamilton chronometers were designed to be mass
produced. Their peak production in WWII was around 130 per week, as opposed
to Mercers in England who reached a peak of 12 per week in 1945. Being
designed for mass production was not a detriment though. Those who are
knowledgeable on the finer points of chronometer design seem to rate
Hamiltons as the peak in evolution of the mechanical chronometer design.

Having compensated for temperature, the biggest problem in the rating of
mechanical chronometers is air pressure. The denser the air, the slower
they run. There is not much that can be done about this in a small clock.
Quartz chronometers do not suffer from this problem.

Geoffrey Kolbe





At 03:26 06/01/2009, Bruce Hamilton wrote:
>
>
>Thank you everyone for answers so far. The most economic solution is of
>course a wristwatch. If it is worn all the time, it will have a more
>constant temperature and be more accurate. I would love to see a graph
>of error vs temperature.
>
>There is a bit of the luck of the draw with them. I had one Timex that
>would loose less than a second every three months, but it now beeps with
>the fishes.  My present one is less accurate. The manufacturers
>obviously have some standards, but they vary quite wildly.
>
>Geoffrey Kolbe also warned us that there is a burn-in period of a few
>months. He used a small quartz alarm clock as well as a wrist watch ,
>but I can't recall how it was for accuracy.
>
>I love fine mechanical devices and would not turn down a mechanical
>chronometer if given to me, but they are getting a bit pricey for my
>budget. If I had that kind of cash, I'd get a Bretling.
>
>Cheers
>
>Bruce Hamilton
>Vancouver, BC


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