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    Re: Sextant Accuracy and anomalous dip
    From: Bruce Stark
    Date: 2003 Mar 23, 20:22 EST

    Jared,
    
    I'll try to explain "fresh rate" and put it in context. I'm no expert on
    chronometer management, so others may have to correct or fill in.
    
    Every chronometer had with it a paper giving its "Original Error" and "Rate."
    The original error was how fast or slow it was on Greenwich time when last
    examined, together with the date and hour the error was found. The rate was
    how much it was gaining or losing per day when the error was found.
    
    At sea, when an observation was timed with the chronometer, the original
    error was applied to the chronometer reading. Next, the number of days and
    hours since the date of the original error were counted up. The rate was
    multiplied by these elapsed days to find how much the chronometer had gained
    or lost since the original error. This too was applied to the chronometer
    reading. The result was the Greenwich time, per chronometer, of the
    observation.
    
    But chronometers had a way of changing rate. That's why careful navigators
    went to the trouble of getting a "fresh rate" whenever they could. That is,
    establishing afresh the chronometer's rate of gain or loss.
    
    Bruce
    
    
    

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