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Francis Drake at Campbell Cove

by Bob Graham

A DEMONSTRATION AT CAMPBELL COVE: On October 6, 1999, Brian Kelleher (right) issued a press release announcing a meeting at noon on October 30 at Campbell Cove. Following an article and announcement by Carl Nolte, San Francisco Chronicle Staff Writer, on the 29th, about 45 people attended.

The intent of this meeting was to provide a demonstration by this writer (left) of Drake's ability to read the altitude of the sun with an astrolabe or quadrant, and to show what his determination of latitude would have been. It was a bright clear day with a light breeze from the northwest. Typically, for this place, the actual horizon was obscured by mist. The astrolabe requires no visible horizon, so this would be no problem.

On this day, due to the equation of time, the sun was approximately 16 minutes before the clock. Campbell Cove (123 W) is also 3 degrees west of the 120th meridian Pacific Standard Time 12:00, making it 12 minutes late by the clock. Therefore, the actual meridian transit of the sun (see watch in photo) occurred at about 12:56 PDT (11:56 PST).

About the watch and how easy it is today to carry the correct time about.

The computed angle that the sun was expected to rise to was 38° 01' 37". The highest angle (see spot of sunlight passing through the foresight and projected onto the back sight in the photo) that could be read on the scales of both the astrolabe and quadrant was 38 degrees. Applying standard modern reductions for the day and longitude to the 38 degrees of the sun's altitude resulted in a determination of latitude of N38° 19'. The actual latitude by GPS was N38° 18' 19".

To show the determination that Drake would have made, the solar declinations of William Bourne (for October 20 old calendar, applying the rule for the obliquity of the ecliptic to bring them up to 1999) were then used. Because Drake could not, the declinations were not corrected for longitude. This reduction resulted in a determination of N38° 24'. This is about +7 miles north of the actual position. It is, however, a very good determination due to the season of the year.
The error near the solstice, when Drake's visit occurred, would have been larger. This is reproduced on the right, which shows the altitude of the sun as Drake would have observed it on June 30 (old calendar). The sun is, of course, much higher at its meridian--much higher than it would have been possible to measure using the cross staff. During the 37 days of his stay, a noon sighting of the sun at Campbell Cove (N38° 19') would have yielded a determination ranging from N38° 24' to N38° 42'. The average determination would then have been N38° 30', exactly as recorded in The World Encompassed.

The publication of The Famous Voyage (1596) predates the appearance of The World Encompassed (1628). However, the latter includes far more detail than the earlier publication. This added detail cannot be invention, or filler, as it includes details of the peoples encountered (Pomo and Coast Miwok) and places visited which can be verified. The two accounts must have come from the same original source.
See a side by side comparrison: The World Encompassed.

So, was the detailed latitude determination for New Albion (only) in The World Encompassed deliberately distorted for some reason? Does it purposely misstate the latitude of Drake's landing place at Nova Albion (conspiracy theory?), or does it record "N38deg.30.min" because that was indeed Drake's determination?
14th Century English philosopher William of Ockham said, "entities must not be unnecessarily multiplied." Well, he wrote it in Latin, actually--entia non sunt multiplicanda praeter necessitatem. This has become known as "Ockham's Razor." What does it mean? Click the picture!


go What does the Drake Navigators Guild (the DNG) say about the latitude of Drake's landing site? This page includes my analysis of the Guild's accepted latitude.


email interest, comments, or questions.

Bob Graham