As I have no intention of getting up in the middle of the night to stare at the clouds preventing me from seeing the last half hour of the transit of Venus I thought instead I would write a, for the meantime, last short post about the history of this event.
For the English the most well known of all expeditions to observe a transit of Venus is the Tahiti expedition of 1769. It is the most famous because it was the first of James Cook’s three expeditions to explore and map the Pacific Ocean. Expeditions that would make Cook one of the most famous British explorers of all time. The articles written and published in recent months on the history of the transit observations have heavily featured the Cook Tahiti expedition but in doing so all of them have made a serious error of omission. They all talk about the Tahiti expedition as if it was Cook’s expedition, it wasn’t, Cook was actually only the driver, the scientific leader of the expedition was Charles Green.
Now most of the people reading this have almost certainly never heard of Charles Green and it is Green’s historical fate that he has been swallowed up by the immense shadow cast by the heroic profile of James Cook.
The Royal Society had decided to sponsor an expedition to the Pacific to observe the 1769 transit, which would not be visible from most of Europe. With this intention they petitioned the King, George III, to order the Royal Navy to supply the necessary transport for the expedition. The King agreed and issued the necessary royal warrants. This then led to the question, who should be in command of the ship? The Royal Society wanted the command of the ship to be in the hands of the astronomer assigned to the expedition, the Royal Navy did not concur.
In 1698 the astronomer Edmond Halley had been given command of a Royal Navy vessel, The Paramour, in order to conduct a survey of the variation of the compass in the Atlantic. The idea was that should these variation turns out to confirm to a pattern, as had been believed by many people since their discovery in the preceding centuries, then they could be used to determine longitude. Halley the landlubber and the Royal Navy seamen did not see eye to eye and Halley was forced to return to England and charged his crew with insubordination. The result of the court case can best be regarded as a draw the crew being given a mild rebuke and Halley a temporary commission to finish his scientific investigations. The Royal Navy had not forgotten this incident and was not keen to give another astronomer command of one of their vessels.
In the end a compromise was found and a young naval lieutenant with experience in cartography and thus astronomy, James Cook, was appointed ships captain and Charles Green was appointed the scientific leader of the expedition. Green himself had earlier been an assistant astronomer at the Royal Observatory in Greenwich under both Bradley and Bliss but on the appointed of Nevil Maskeline to the post of Astronomer Royal in 1765 he had left the observatory and joined the navy as a purser. Green had in 1763/4 conducted the second sea trial of John Harrison’s H4 chronometer on a sea voyage to Barbados with Maskelyne as his assistant and the two men apparently did not get on. The relative status of the two naval astronomers, Green and Cook, on Tahiti is reflected in their gratuities from the Royal Society for the transit observations; Green was awarded 200 guineas whereas Cook only received 100 guineas. This was Green’s transit of Venus expedition and not Cook’s.
The two men apparently got on well and Cook commented favourably in his ship’s log on Green’s abilities as an astronomer. On Tahiti they successfully observed the transit of Venus together with a young Joseph Banks, the expeditions natural historian, who would go on to become one of the dominant figures of the British scientific establishment in the second half of the eighteenth century and on into the nineteenth.
After completing their observations came the historical moment in which Cook opened his secret orders and instead of returning to Britain set off to explore the Southern Pacific in search of the great southern continent. Green had no choice but to continue the journey and together they circumnavigated New Zealand charting the coastline as they went and then explored and mapped the east coast of Australia where Cook named Green Island after his astronomical companion.
They headed home via Indonesia and whilst refitting in Batavia Charles Green took ill and died on the home leg of the voyage on 29th January 1771. Cook would go on to great fame and a secure place in the history books whilst Green has become lost in his shadows. When we think of the history of eighteenth century astronomy we should remember that it was Charles Green’s expedition to Tahiti to observe the transit of Venus, James Cook was just the driver.
As a footnote to this story I want to point out another of those historical horrors in accounts of the transit of Venus observations. Phys.Org has a piece by a Dr Tony Phillips on “Cook’s” voyage to Tahiti to observe the transit, which is littered with the usual minor errors and which only mentions Charles Green in passing as one of those who died after to stopover in Batavia. All of this is par for the course for such pieces but the good Dr Phillips manages one error that would cause consternation in the British cultural establishment. He writes:
Their mission was to reach Tahiti before June 1769, establish themselves among the islanders, and construct an astronomical observatory. Cook and his crew would observe Venus gliding across the face of the Sun, and by doing so measure the size of the solar system. Or so hoped England’s Royal Academy, [my emphasis] which sponsored the trip.
Now the Royal Academy had been granted its charter by George III in 1768 so it is of course just possible that they had sponsored the trip. However as they are a society dedicated to promoting the creation, enjoyment and appreciation of the visual arts through exhibitions, education and debate it is highly unlikely. The expedition was, as I have already written above, of course sponsored by the Royal Society a completely different body dedicated to the promotion of the natural sciences.