Ship Wrecks And Deaths

The High Cost Of Ignorance

The effects of not being able to calculate longitude were profound. The distortion of maps due to guesswork in east-west positioning (which resulted in the wrong charting of land masses in particular) and the inaccurate charting of land masses was a hazard for sea-faring travellers. Just how hazardous is exemplified by the experience in the eighteenth century of a British naval officer, Commodore Anson. In 1740 Anson and his crew sailed from Britain past Cape Horn to Manila and then onwards back to Britain. During this trip they pillaged a Spanish galleon of half a million pounds worth of treasures. Of the 1939 who began the journey, 1051 died as a result of the poor conditions on board ship. Anson had expected to relieve conditions and obtain fresh supplies at Juan Feranandex, a small island west of Cape Horn but he was unable to find it because he could not determine longitude accurately enough. Normally, to locate a target such as an island, a navigator of this time would sail along its known latitude until the target was sighted. Aware of his crew’s failing condition, Anson sought to save time by diverting from this practice. Instead he set sail directly north from his position for Juan Fernandez. He followed his charts, but reached the given latitude without sighting the island. Ignorant of this his longitudinal position, he was not sure whether to turn east or west. First he turned west and actually ran to within a few hours sailing from the island. He then turned and ran east all the way back to the coast of Chile which at least gave him an east-west landmark (Benthon and Robinson, 1991:117). He never did find Easter Island and his losses continued. The fame of his plunder was to make him First Lord of the Admiralty in spite of the fiasco.

The problems encountered by Anson were not new and they persisted after him. The hazards of sea travel during the 15th century are clearly illustrated by Columbus' experience. His journal reveals that he did not know even how to calculate latitude properly, his determinations being far too high. Moreover he, like all sailors at the time, was unable to calculate longitude (Williams, 1992:76). Columbus, when he encountered the Americas actually thought he had reached India which explains why the names Indies and Indians are still attached to the lands he found.

As well, near the equator where Columbus was sailing, the meridians are travelling even faster than they did at lower latitudes (because the equator has the greatest circumferential distance to cover in the 24 hours of each rotation), so the consequences for error more profound. After a few weeks at sea the inaccuracies in the clocks could produce an error in longitude of thousands of nautical miles. It is likely that the best clocks in the land at the time lost 10 minutes a day which translates into an error of 175 miles. But not even this daily loss could not be relied on, so it could not be compensated for (Williams, 1992:78).

During the sixteenth century the Spaniards and Portuguese both regularly navigated across the Atlantic apparently relying only on estimating of east-west distances. Martin Fernandez De Enciso writing in 1519 recorded that: "Sailors calculate distance in an East-West direction in nights and days and with an hourglass and the calculation is reasonably correct for those who know their ship well and how much it sails in an hour...Because their estimation is approximate...they over-estimate rather than underestimate the number of leagues so as to be warned of their approach to land, rather than running upon it suddenly..." (Randles, 1995:402).