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Lu Abel wrote:
> I've found cheap Timex or equivalent
> quartz watches to be remarkably good timekeepers (at least on my wrist,
> I've never taken them off and subjected them to freeze-boil cycles) --
> if given the chance to measure watch rate, I'd be pretty confident of
> going for a month or even more without cross-checking with WWV or
> equivalent.

Here are the daily rates of my $25 Timex Expedition for the last year. I
actually check it only once per month, and convert the error to the
equivalent daily rate for that month.

+.43 March 2007
+.41 April
+.41 May
+.40 June
+.35 July
+.34 August
+.40 September
+.45 October
+.44 November
+.43 December
+.42 January 2008
+.42 February
+.45 March

This watch was bought in 2000. The original battery is still installed,
though for about a year it's been so weak that the display goes blank
when I press the illumination button. The watch still keeps good time,
so I haven't bothered to get the battery changed.

There seems to be a remarkably consistent relationship between seasonal
temperature changes and watch rate. In the table above, the fastest
rates are +.45 in October 2007 and March 2008. The corresponding values
a year before were +.43 and +.43. The slowest rates are +.35 and +.34 in
July and August, compared to +.26 and +.35 a year before. That +.26 is
not a typo. However, it may be significant that the anomalous value
occured when I forgot to do my monthly check until the middle of the
month. So "June" had 6 weeks and "July" had 2 weeks. I may have made a
mistake in my math. The consistent values from May and September tend to
confirm that suspicion. The respective rates were +.39 vs. +.41, and
+.40 vs. +.40, for 2006 vs. 2007.

For the correct time, I call WWV and the USNO on my Nextel cell phone.
The delay is about 1/4 second compared to WWV on shortwave radio. It's
so  consistent that I make no correction for the delay. I used to tune
WWV on the shortwave radio for my time reference, but sometimes the
propagation was bad on all frequencies. It's less trouble to use a phone.

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