Sobel establishes the rule that exact knowledge of the hour in two places at once is
necessary to navigate with accuracy. However, due to mechanical problems, it was
impossible to know the exact time on board ships up to and including the use of
pendulum clocks. Therefore, all captains in the Age of Exploration must have spent
a great deal of time lost at sea. What kind of reasoning leads Söbel to reach this -
conclusion?
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