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Huyghens timekeeper attempt.
From: George Huxtable
Date: 2009 Dec 1, 12:15 -0000
From: George Huxtable
Date: 2009 Dec 1, 12:15 -0000
This piece, from the very first issue of Philosophical Transactions (1665) vol 1, pages 13-15, has some navigational interest. Some notes- "Major Holmes" is better known as Captain Robert Holmes, later Sir Robert. His destination, rather badly printed on line 3, was Guinea, on the coast of Africa. His voyage, with a small fleet, was a Royal-sponsored adventure, to break the profitable slave-trade monopoly of the Dutch, for the benefit of the newly-formed "Company of Royal Adventurers Trading into Africa". (See Ted Gerrard's book "Astronomival Minds".) It worked, for a year, until the Dutch restored the status quo. "The Isle of St Thomas under the line" was Sao Tomas, at about zero degrees latitude (hence "under the line") and about 6 degrees 30' East of Greenwich (though Holmes was unlikely to know that). "Adjusting his watches" there implied that any longitude changes would be relative to the longitude of Sao Tomas, whatever that was worth.. Going homeward, Holmes' enormous diversion, to the West, made sense, in taking advantage of the circulation pattern, as the Portuguese had discovered. Even to modern times, the sailing-ship route from the East to the English Channel followed a mid-Atlantic track, . Sailing Northwestward from Guinea through the Bight of Benin was unprofitable. If his pilots were proposing to touch at Barbados for water, when no more than a day's sail from the Cape Verdes, their notions of longitude must have been way adrift. It didn't call for much precision, from a timepiece, to do better than that. But Holmes' good experience, with Huyghens' marine timekeepers, was not replicated by others. One great problem, with pendulum timekeepers at sea, was the difficulty of simply keeping them going at all, in rough weather. Perhaps that was the main reason for carrying two, in the hope that if one stopped, the other might carry on. But even if all the problems of ship's motion had been resolved, a pendulum would never make a good timekeeper for ocean travel, subject as it is to the variations in gravity. It would be another century, after abandonment of the pendulum, before Harrison came up with a dependable marine timekeeper. Holmes made the most of his stop for water by seizing the Cape Verde Islands for England, another claim which would be reversed before long. Holmes had a talent for stirring up trouble, and his actions were a trigger for the Second Dutch War. Huyghens' references to the "States" presumably refer to the United Provinces of the Netherlands. A good article on "The Longitude Timekeepers of Christiaan Huygens" by J H Leopold, is on pages 102-114 of that superb volume "The Quest for Longitude", ed. W. Andrewes, (1996). George. contact George Huxtable, at george@hux.me.uk or at +44 1865 820222 (from UK, 01865 820222) or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com