do the marks between the "+" and "-" represent a given amount of time over 24 hours, or is it just trial and error with the marks there as only reference points? does it depend on the manufacturer? thanks, tim

I think they are only there for reference purposes, but it sure would be nice if each mark meant + or - so many seconds per hour.

The only watch movement I've ever seen where the marks corresponded to so many seconds per DAY was that used in the Bulova "Accutron" watches. At the ends of the tuning forks in those movements, there were tiny counter weights that could be moved around by rotting "notches" on them past a tiny dot pressed into the fork's tines. This was easily done with a jeweler's screwdriver.

Moving these counter weights upward away from the base of the fork would slow the rate of time keeping because it lowered the frequency of the fork by slightly increasing the distance between the base of the fork and the center of mass at the ends of its tines. OTOH, moving the counter weights downward toward the base increased the rate of time keeping because that decreased the distance between the center of mass of the ends of the times and the base which then increased the frequency of the fork.

IIRC, moving EITHER counter weight by one notch correlated with a change in time keeping rate of 2 seconds per day and one could easily adjust the movement to keep time to WITHIN two seconds per day. In the pre-quartz world of watches, this was considered incredible accuracy.


technoguy

thanks for the info. of course two seconds per day is enormous compared to the quartz accuracy, but it's still very good in any case. i'm happy with two minutes, though i find some of my timexes can be less than 30 seconds with any luck. tim