In Eclipse: Journeys to the Dark Side of the Moon by Frank Close, it is stated that the 1584 lunar eclipse was used to determine the width of the Atlantic, by measuring the times in London and in Virginia. However, I cannot seem to find any other source, except at his RI talk.

I would like to know if this claim is true, and if yes, some more historical details (such as the names of the people involved) on it.

Note that the question is not about the methodology, but about the historical fact, whether or not the claimed measurement happened. It would also be great to know about histories of measurements similar to this.

In contrast, this related question focuses on the basic methodical aspect of such measurements.

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    $\begingroup$ It was well-known that "time equals longitude", and a method for determining it using lunar eclipses was proposed already by Hipparchus (marking the difference in local times when the eclipse is observed). Vespucci claimed to have used this method in 1502. One can then find the distance between London and Virginia knowing the latitudes and the circumference of the Earth. $\endgroup$
    – Conifold
    Jan 5, 2020 at 2:20
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    $\begingroup$ @Conifold: I was not asking how it is possible, but whether the claimed event happened. $\endgroup$
    – timur
    Jan 5, 2020 at 2:54
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    $\begingroup$ Thomas Harriott springs to mind as someone who might have done this, except he did not seem to arrive in Virginia until 1585, and does not seem to mention it in his Brief and true report... . $\endgroup$ Jan 5, 2020 at 15:07
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    $\begingroup$ Spaniards arranged global observation of eclipses in 1570-80s, including 1584:"What makes the enterprise remarkable is the sponsorship and the execution. Preparations were made under the auspices of the Royal Academy of Mathematics in Madrid and the Royal Council well enough ahead of time to supply observers in Antwerp, Venice, Sevilla, Toledo, Madrid, and Mexico City with identical instructions for an "instrumento", i.e., a uniform-sized sheet containing a half circle of the same radius, to register the sightings." see Lamb. $\endgroup$
    – Conifold
    Jan 5, 2020 at 15:28
  • $\begingroup$ Timur, you question is "Was ... first determined ..." So Conifold's comments on earlier measurements is valid. $\endgroup$ Jan 6, 2020 at 13:47


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