new item

new item


New World Longitude and Drake's Circumnavigation.
Bob Graham
Copyright © 2013

In the Pacific Ocean just west of Magellan's Strait at the tip of South America.
On September 6, 1578, Drake's fleet that had entered the Pacific consisted of three ships: Drake's ship the Golden Hind, the Elizabeth, Capt. John Winter, and the Marigold, Captain Edwin Bright (or John Thomas). They were immediately met with a tremendous storm that lasted for 52 days.
The following three narratives tell of the observation 9 days later of a partial lunar eclipse, and, in one account, how the time of that observation gave the longitude west of England.

A Hakluyt, The Famous Voyage, 1586 (sources unknown):
The 6th day of September we entered the South Sea at the cape or head shore. The 7th day we were driven by a great storm from the entering into the South Sea, 200 leagues and odd in longitude, and one degree to the southward of the Strait; in which height, and so many leagues to the westward, the 15th day of September, fell out the eclipse of the moon at the hour of six of the clock at night.

B Edward Cliffe's account of his voyage in the Elizabeth (Capt. John Winter). Published by Hakluyt in 1590.
The 15 of September the Moone was there Ecclipsed, and began be darkened presently after the setting of the Sunne, about 6 of the clocke at night, being then Equinoctial vernal in that countrey. The said Ecclipse happened the 16 day in the morning* before one of the clocke in England, which is about sixe houres difference, agreeing to one quarter of the world, from the Meridian of England toward the West.

C Francis Drake (Bart.), The World Encompassed, 1628 (sources Francis Fletcher, and divers others):
In the time of this incredible storm, the 15 of September the Moon was eclipfed in Aries ♈ and darkened about three points, for the space of two [hour] glasses; which being ended, might seeme to give us some hope of alteration & change of weather to the better.

Both the Cliffe and Hakluyt accounts (perhaps originally from the same source) say the eclipse was observed in the Pacific, somewhere south of the western entrance to the Strait of Magellan, beginning at "six of the clocke at night" on September 15th.
TWE says that the eclipse, "in aires" ♈ lasted for "the space of two glasses" (2 hours), putting the time of maximum eclipse (axis of Earth's umbral shadow) at about 7 p.m. in the Pacific. (clock face at right).
If so, there were 5 hours and 21 minutes time difference, (not 6 hours as stated by E. Cliffe) between their position at 7 p.m., Sept. 15 and 12:21 a.m., Sept. 16, London time.
(see the 16C eclipse catalogs below for dates and exact times)
4 minutes of time is equal to 1 degree of longitude, so 5 hours and 21 minute puts their position near the 80th meridian, as on the map above, not one quarter of the world (90°) as suggested by Edward Cliffe. Or we can use the start times of 6 p.m. in the Pacific and 11:26 p.m. in London and get the same result--about 80 degrees west of London. But we know that the duration of the eclipse was actually 1 hour 46 minutes; so less than the "space of two [hour] glasses" of The World Encompassed. That means that if the eclipse started at 6:00 p.m. their time, the maximum occured at 6:53, making their longitude 82° west of London. Still considerably less than Cliffe's "one quarter of the world."

Almanacs covering many celestial events were published at that date for astronomers, astrologists, and navigators. Someone on the Elizabeth, perhaps Edward Cliffe himself, had an almanac giving the date and time of the forecast eclipse at London--the eclipse was looked for. The difference in time by the clock between the eclipse at London and the same observed in the South Pacific is the longitude west of London. 1 hour = 15 degrees. Columbus attempted this in 1499 and 1504, but blew it--some think intentionally, to suggest he was further west (ie., the Indies) than he really was.

How accurate? Very accurate, if the ships had had their local time with precision. But the time on ships was only very crudely kept with hour glasses between available weather dependent astronomical observations.
How close was the actual local time to the stated "6 of the clocke at night?" A twenty minute error in time makes a 5 degree error in longitude. Because the storm had been driving them south and east, my own feeling is that Drake's actual longitude was closer to 75° West.

In William Bourne's 1571 An Almanacke and Prognostication for Three Years, under his Eleventh Rule, he says that "to gette the Longitude, you may at the time of the Eclipse of the Moone, for Eclipses of the Moone be generall, so that she is above the Horizon in any place upon the supersticial partes of the earth or sea, considering as I saide before, by your Almanack, at what time the Eclipse should happen the very houre and minute, knowing the place that your Almanack was made for, and then according to this rule [that .15. degrees will aunswere to one hour of tyme,] with a precise instrument the alteration of the time and hour and minute of the Eclipse."
Bourne's calling for the use of a "precise instrument" (timekeeper) is, of course, the rub.

Find the eclipse observed by Drake's fleet in these two online catalogs:

*NASA Catalog of Lunar Eclipses: 1501 to 1600
The maximum eclipse occurred (axis of Earth's umbral shadow) at 21 minutes after midnight (00:21:28) in London on Sept 16, 1578 (dates are Julian--old calendar)

Wikipedia List of 16th century lunar eclipses
The same eclipse started (U1) 23:26, ended (U4) 1:12 (dates are Julian--old calendar)

I do not have a period published almanac for the year 1578, so cannot know the precision or accuracy of the published time of the eclipse. Edward Cliffe says that the forecast time at London was "before one of the clocke in England," which only loosely agrees with the times in the above catalogs: ie., starting at 11:26 p.m.; maximum at 12:21 a.m.; ending at 1:12 a.m. Perhaps the times published in the ephemerides were not very exact. See the following example.

Here an eclipse from William Bourne's An Almanacke and Pronostication for X yeeres, beginning the year of our Lord 1581 and ending the year 1590, Being calculated for the Meridian of London of a forecast eclipse for the year 1584

This yeere of our Lorde I584, there is an Eclipse of the Moon, the vii. day of Nouember, at xi. a clocke iv. minu. at midnight, the Moone being within two degrees of the Dragons tayle, and shalbe darkened xviii. points xiiii. min. and the Moone shall begin for to come vnder the shadow of the earth heere with us at London, before xi. a clocke, and shall continue neere iii. houres from the beginning vnto the ende, and the Eclipse shall be seene due South upon the Meridian, when that it is at the greatest.

Beginning "before xi. a clocke" and continuing for "neere iii. houres" is not very precise. Compare with Edward Cliffe's "before one of the clocke," and "about sixe hours" in his statement above.

On January 31, 1582, before the start of the Fenton expedition, one of the chaplains on the voyage, Richard Madox, making an accounting of his expenses in his diary, wrote "For an ephemerides...3s 6p." Perhaps this very edition of William Bourne's.

On September 28 the Marigold disappeared and was never heard of again. On October 6 the Elizabeth deserted, reentered the strait, and was returned to England by Captain Winter, leaving Drake to complete the second circumnavigation of the world alone.

NOTE: On his fourth voyage, Columbus had tried to establish his longitude by lunar eclipse on the coast of Central America from the tables of celestial events compiled by Regiomontanis. Timing from his observed sunset with an hour glass, Columbus calculated that the eclipse had occured 7 and one quarter hours later than in Cadiz, Spain, making his longitude 110 degrees West, an error of +33 degrees.

What about Drake's determined latitudes of the Magellan Strait?
The World Encompassed says:
"Onley this by all our men's obseruations was concluded: that the entrance by which we came into this straite was in 52 .deg., the middest in 53 deg. 15 m., and the going out in 52 deg. 30 m.,being 150 leagues in length: at the very entry supposed also to be about 10 leagues in bredth. After we were entered ten leagues within it, it was found not past a league in breadth, farther within, in some places very large, in some very narrow, and in the end to be found no straite at all, but all Islands."

A very accurate description. See the actual latitude values on the map, and the errors in the chart below. Remarkable! considering that all observations were made at sea with storms and famous local williwaws throughout the period. The latitudes reported in The World Encompassed, for known places, and that are presumed to have been made on land, fall within an even more remarkable +/-11 arc minutes. A part of that error is that Drake could not adjust his published tables of daily solar declinations for his longitude west of the place of their calculation, then London. See Determination of Latitude by Francis Drake on the Coast of California in 1579, Bob Graham,1999.

Position and Date TWE
Latitude TWE

the entrance, Aug. 20, 1578

52 .deg.
52° 27'
- 27'

the middest, Sept. ?

53 deg. 15 m.
53° 56'

the going out, Sept. 6, 1578

52 deg. 30 m.
52° 37'

Before Drake could make any progress to the west, the storm blew him even further south and east, all the way to Cape Horn. He discovered that, contrary to then published maps, there was an open sea between America and the southern continent. It is today called Drake Passage.

A Short Bibliography:

  • Bourne, William, A Regiment For the Sea (1574) and Other Writings on Navigation, E. G. R. Taylor, editor, Cambridge, 1963.
  • Darwin, Charles, A Naturalist's Voyage. Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of HMS 'Beagle' round the World, Under the Command of Capt. Fitz Roy, John Murray, London, 1886.
  • Donno, Elizabeth Story, An Elizabethan in 1582: The Diary of Richard Madox, The Hakluyt SocietyLondon, 1976.
  • Drake, Sir Francis (Bart.), The World Encompassed, 1628: Any edition, but especially The Argonaut Press, London, 1926.
  • Graham, Bob, Determination of Latitude by Francis Drake on the Coast of California in 1579, 1999.
  • Kelleher, Brian T., Drake's Bay, Unravelling California's Great Maritime Mystery, Day Publishing, San Jose, 1997. (latitude analysis)
  • Murphy, Dallas, Rounding the Horn; Being the Story of Williwas and Windjammers, Drake, Darwin, Murdered Missionaries, and Naked Natives--A Deck's-Eye View of Cape Horn, Basic Books, New York, 2004.
  • Nuttall, Zelia, New Light on Drake, Hakluyt Society, London, 1914.
  • Taylor, E. G. R., Tudor Geography 1485-1583, Methuen & Co. Ltd., London, 1930.
  • Wagner, Henry R., Sir Francis Drake's Voyage Around the World, John Howell, San Francisco, 1926.
  • Wallis, Helen, The Voyage of Sir Francis Drake Mapped in Silver and Gold, Friends of Bancroft Library, Berkeley, CA, 1979.
  • Waters, D. W., The Art of Navigation, Yale University Press, 1958.
  • Wright, Edward, Certaine Errors in Navigation (1599), Walter Johnson, Norwood, N.J., 1974. 

Bob Graham