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Subject: Re: Sextant Accuracy and anomalous dip
From: Bruce Stark (Stark4677@XXX.XXX)
Date: Sun Mar 23 2003 - 20:22:53 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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