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    Re: How Many Chronometers?
    From: Frank Reed
    Date: 2009 May 10, 23:20 -0700

    Jim Wilson, you wrote:
    "I guess I thought that a chronometer was defined as a clock with a constant rate of change."
    
    That's actually a good definition of a CLOCK. :-) 
    
    Any device or phenomenon that has a constant rate/constant frequency can be 
    used as a clock and all we need is some software or mechanism to count its 
    "ticks" and then also the rate factor that takes us from its natural 
    frequency to the frequency of standard mean time. The word "constant" here 
    implies that the clock is unaffected by "external influences" and atomic 
    clocks come close to this ideal, but in practice we can deal with clocks that 
    have predictable behavior under the influence of external influences, like 
    temperature corrections for the rates of traditional mechanical chronometers.
    
    Irrelevant to practical matters (until recently) but relevant to the whole 
    science of time, this business of a "constant rate" becomes very tricky when 
    we deal with general relativity since the rate of time itself depends on 
    location, specifically our "depth" in a gravitational field (height above sea 
    level or height above the geoid for us earthlings).
    
    -FER
    
    
    
    
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