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Pastimes : Authors & Books & Comments
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To: Tom Clarke who wrote (386)12/12/2007 10:08:37 PM
From: ManyMoose  Read Replies (1) of 9622
 
Thus a common sailor and buccaneer who is also at the cutting edge of scientific study seems somewhat incredulous to the modern reader.

That report brought to mind a book that I recommend. "The Navigator" by Morris L. West is a fictional account of western mariners before celestial navigation was highly developed. In those days, mariners were confined to running coastlines, lest they become completely lost. There was no way to tell latitude nor longitude.

Arab navigators learned a trick so simple that a child could do it but so powerful that the holder of the secret would defend it to the death, and those who knew he had it would kill or go to war to get it.

The plot dramatizes how the western mariners might have obtained this trick.

The instrument is a chip of wood on a string. The navigator holds the string against his cheek and orients the chip of wood on the horizon towards Polaris. He ties a knot in the string at the length where the chip exactly spans the gap between the horizon and Polaris. That length of string records the reference latitude, presumably of his Port.

If the mariner is out of sight of shoreline, all he has to do is relocate Polaris and repeat the sighting. If Polaris is higher than the span of the wood chip, he is North of the reference latitude and if Polaris is lower he is South.

All that remains is to return to the Port's latitude and head east or west by the compass to return to it.

Simple, but so precious people would die for it.

The ability to precisely determine longitude came much later, and required mechanical clocks that measured time accurately without a pendulum, which would be disturbed by the ship's motion at sea.
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