Dudingston's decision to move Fortune to Boston…

British naval officer James Cook prepares to observe the solar eclipse of the planet Venus, having arrived sailing from Cape Horn to Tahiti on the ship HM Bark Endeavour on April 13, 1769, and commissioned the building of a small fort and observatory at what is now known as Point Venus.

The astronomer appointed to the task is Charles Green, assistant to the recently appointed Astronomer Royal, Nevil Maskelyne.

The primary purpose of the observation is to obtain measurements that can be used to calculate more accurately the distance of Venus from the Sun.

If this can be achieved, then the distances of the other planets can be worked out, based on their orbits.

The transit takes place on June 3.

Disappointingly, the separate measurements of Green, Cook and Solander vary by more than the anticipated margin of error.

Their instrumentation is adequate by the standards of the time, but the resolution still cannot eliminate the errors.

When their results are later compared to those of the other observations of the same event made elsewhere for the exercise, the net result is not as conclusive or accurate as had been hoped.

The difficulties are today thought to relate to the Black drop effect, an optical phenomenon that precludes accurate measurement—particularly with the instruments used by Cook, Green and Solander.

Once the observations are completed, Cook opens the sealed orders for the second part of his voyage: to search the south Pacific for signs of the postulated rich southern continent of Terra Australis, acting on additional instructions from the Admiralty.

The Royal Society, and especially Alexander Dalrymple, believe that it must exist and that Britain's best chance of discovering it and claiming its fabled riches before any other rival European power manages to do so would be by using Cook's Transit of Venus mission (on an inconspicuous small ship such as the Endeavour) as a cover.

Cook, however, has his own personal doubts on the continent's existence.

Domingo Bernardo de Bonechea, commanding an exploratory expedition to Tahiti commissioned by the Viceroy of Peru, Manuel de Amat y Juniet, sails with Tomás Gayangos as his lieutenant on the Aguila, Santa Maria Magdalena, from Callao harbor, Peru, and reaches Tahiti on November 7, 1772.

He anchors opposite Tautira village, which de Bonechea christens "Santísima Cruz".

De Bonechea forbids himself and his crew any sexual relations with local women, which surprises the Tahitians greatly.

He leaves Tahiti on December 20 and will reach Valparaíso, Chile, on February 21, 1773.

Georg Forster, who had accompanied Cook on his Second Voyage, refers to him as "Domingo Buenechea".

 

The aim of de Bonechea's second expedition is the annexation of Tahiti to the Spanish crown, with the approval and encouragement of King Carlos III, and to convert its inhabitants.

Two ships, the Aguila and the Jupiter, had left Callao on September 20, 1774.

After winning over Tu, the most important king of the Tahitians, de Bonechea's men are allowed to establish a mission.

However, de Bonechea dies on January 20, 1775, in Tahiti, where his grave, which had been dismantled on Captain Cook's orders, will be rediscovered in the twentieth century in the village of Tautira.

The Spanish mission on Tahiti is abandoned on November 12 the same year and the whole enterprise comes to an early end.