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 which Baron Nordenskiöld has written as follows to Sir Clements Markham:—

The ascertaining of the longitude continued for many generations to be a difficulty, although Werner of Nürnberg proposed the method of observing the distance of the moon from the sun with simultaneous altitudes—a method subsequently known as taking a "lunar"; and Gemma Frisius of Louvain had an idea, made public in 1530, that longitude might be found by comparison of times kept by small clocks, a foreshadowing of the modern use of the chronometer.

Columbus was the first to observe the variation of the needle. This was on September 14th, 1492. It afterwards attracted the attention of Sebastian Cabot. But the peculiarity was very generally believed at the time to be non-existent, the observations being inaccurate; and, as late as 1571, Sarmiento doubted it.

Globes, and not charts, were chiefly used by the early