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thinking outside the tank

Captain Cook in Google Earth: Batavia to Cape Town

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Endeavour sailed from Batavia on 27Dec1770. It was slow progress at first and they had to anchor the ship frequently to avoid losing ground against contrary tides and currents.

In Sunda Strait, the ship sailed within 3 miles of the island of Krakatoa, which must have had a very different appearance in January, 1771, than it did after its violent eruption in 1883.

Cook stayed over a week anchored off Prince’s Island, at the south-east end of the strait, to stock up on wood, water, and food before making the journey across the Indian Ocean to the Cape of Good Hope. They set sail on Tuesday, 15Jan1771 and progress was still slow owing to light and variable winds.

(See my previous post about the deaths of 23 members of the crew from dysentery)

Once she was in the south-east trade winds, Endeavour started to cover between 100 and 150 miles per day, arriving rather abruptly, and surprisingly, off the African coast on Tuesday, 05Mar1771:

In the evening some people thought they saw the appearance  of land to the Northward; but this appear’d so improbable that I, who was not on deck at this time, was not acquainted with it until dark, when I order’d them to sound, but found no ground with 80 fathoms, upon which we concluded that no land was near. But daylight in the morning proved this to be a mistake by shewing us the land at the distance of 2 Leagues off (about 6 miles).

Cook began to appreciate the strength of the currents that had carried Endeavour to the west and the south of her position determined by dead-reckoning. Remember that Cook did not yet have access to one of John Harrison’s chronometers and the determination of longitude was still a tricky business (though Cook was one of the most meticulous observers). On Wednesday, 13th Cook wrote in his journal:

Latitude observed 34 degrees 15 minutes South; Longitude in, by our reckoning, corrected by the last observation, 341 degrees 7 minutes West, or 18 degrees 53 minutes East from Greenwich, by which the Cape lies in 34 degrees 25 minutes South Latitude, and 19 degrees 1 minute East Longitude from Greenwich, which nearly agrees with the observations made at the Cape Town by Messrs. Mason and Dixon in 1761; a proof that our observations have been well made, and that as such they may always be depended upon to a surprizing degree of accuracy. If we had had no such guide we should have found an error of 10 degrees 13 minutes of Longitude, or perhaps more, to the East, such an effect the current must have had upon the ship.

I assume that the men Cook refers to were the British experts Charles Mason (astronomer) and Jeremiah Dixon (surveyor) who were commissioned in 1763 to resolve the border dispute between the British colonies of: Pennsylvania, Maryland, Delaware, and West Virginia. They had been in Africa because, like Cook, they were despatched on a mission to observe a transit of Venus (the 1761 transit). They never reached their destination of Sumatra and instead were forced to observe the transit from the Cape of Good Hope.

You can now view the part of Cook’s first voyage round the world between Batavia and Cape Town by visiting http://www.hazelhurst.net/Cook/. The website has over 15 hours of animation and audio presenting Cook’s voyage in the Google Earth plugin.

Copyright © Colin Hazlehurst, 2012

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