NavList:

Hi George

You wrote:
Even as late as 1767, such an experienced navigator as James Cook was not
noting his longitudes as from Greenwich, in his North Atlantic crossings.
They were always from the point from which he took his "departure" ...Never from Greenwich, much to my surprise.

This means that he was using incremental reckoning, not absolute reckoning. Truly interesting! The problem with this type of reckoning is the accumulation of round-off.

Example: I went west 1.234 degrees on day 1 and on day two, I went west 2.345 degrees. Since that is 'too many' digits to write, on day 1, I record 1.2 degrees and on day 2, I record 2.3 degrees. How far west am I? According to my records 3.5 degrees, when I actually went west 3.579 degrees. Make this 1000 days, and you get the picture.

Cook was out exploring for years, if I have it right. Therefore his records must show a gradual shift in longitudes with respect to time. Does your research show this outcome?

Best Regards
Brad

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