Archived posting to the Leica Users Group, 2000/09/16

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Subject: Re: [Leica] mechanical watches
Date: Sat, 16 Sep 2000 16:31:24 EDT

In a message dated 9/15/00 8:19:03 AM Eastern Daylight Time, 

<< When I bought my Tudor Submariner the dealer showed me an old Rolex 
information sheet
 which explained one should store a mechanical watch flat with face up to 
gain time,
 sideways with crown down to loose a little time, crown up to loose more time.
 Apparently gravity affects accuracy.  >>

Indirectly, it can.  To understand how, visualize a watch movement, with the 
balance wheel plano-parallel to the plates which serve as the chassis.  The 
balance is like a bicycle wheel, in that it is mounted on an "axle" known as 
the "staff", suspended between two carefully lubricated jewelled bearings or 
mountings, on points called "pivots".  When the watch is on its back, the 
balance rests on the lower jewel.  When it is stood on edge, it is suspended 
like a bicycle wheel during forward motion.
As mentioned by another LUG'er, watches are factory "adjusted" so as to run 
at set rates in as many as 6 positions, although more are used, but very 
infrequently.  The ultimate goal is to have the watch run as accurately as 
possible in actual use.  Extreme precision is required, compared to, say, a 
mantel clock, which needs to run in only one position.  An ideally adjusted 
watch will not show measurable differences in running rates in different 
positions.  A well adjusted watch with little wear may not either, on a daily 
basis.  But most watches are not operating optimally, let alone ideally.
It is not gravity which alone changes the rate at which a watch runs, but a 
combination of physical forces which, among others, includes friction.  
Physicists or watchmakers receiving this post are welcome to correct my 
simplistic and probably inaccurate account!

Joe Sobel