In 1768, Captain James Cook set sail on his first epic voyage aboard the Endeavour. The three-year expedition was to become one of the greatest journeys of European exploration in history, and Cook is now most famous for the contact he and his crew made with the islands of the South Pacific en route. The reason his voyage was commissioned in the first place is less well known. It was in fact a scientific mission, organized by the Royal Society of London.
The eighteenth century was the time of the Enlightenment, an era characterized by a tremendous thirst for knowledge. One of the hallmarks of the age was a great enthusiasm for scientific enquiry, with many new studies being carried out in a wide variety of areas, including geography, natural history, and the universe as a whole. The British Royal Society had been formed in the mid 1600s as a forum for learned men to discuss scientific issues. Fellowships of the Royal Society were then, as they are now, earned through an individual¡¦s achievements in science.
The Royal Society was interested in all matters scientific and, at the time Cook¡¦s journey was proposed, had a special interest in one of the burning issues of the time, the problem of how to measure the distance of the Earth from the Sun. Such a measurement, it was believed, would contribute greatly towards a much better understanding of the universe and how it operated.
Just how to obtain such a measurement had been the subject of a great deal of thought, and in 1716, astronomer Edmond Halley hit upon a possible solution. Halley suggested that an accurate calculation of the distance of the Earth from the Sun could be obtained by taking simultaneous measurements of an astronomical phenomenon, the transit of Venus, from widely spaced geographical locations.
The transit of Venus occurs when the planet Venus passes directly between the Earth and the Sun, and its unlit side can be seen as a small black circle moving across the face of the Sun. By observing this phenomenon, the speed of the planet¡¦s orbit can be calculated, and through trigonometry, the Earth-Sun distance (known as the Astronomical Unit) can be determined.
Because of the way the orbits of all three bodies coincide, transits of Venus occur in pairs, eight years apart, approximately once every 120 years. There had been a transit of Venus in 1761, during which a large international team of scientists had traveled to different parts of the world to make observations. Unfortunately, due to a variety of circumstances, the results from this expedition were not precise enough to yield an accurate calculation of the astronomical unit.
The next transit of Venus was calculated to occur on the 3rd of June 1769, and the Royal Society was eager to be at the forefront of new efforts to measure it. As well as the intrinsic scientific interest created by such an activity, the Society was particularly anxious to extend Britain¡¦s role in this scientific endeavour, as there had been only a few English scientists amongst those who took part in the first attempt to measure the transit. As a result, the Royal Society proposed a journey to the south Pacific to measure the second transit of Venus from Tahiti.
When the British Admiralty heard of the Royal Society¡¦s plans for a voyage to the south Pacific, they were extremely interested, as they too had been considering a journey to that same region, but for a very different reason.
For many years, it had been thought that a landmass, the ¡§Great Southern Continent¡¨, existed in the southern hemisphere. Such a landmass would be essential, some insisted, in order to balance the large landmasses of the northern hemisphere. Without it, they reckoned, it would not be possible for the earth to rotate properly on its axis. So sure were people of the continent¡¦s existence, that for years, maps had featured the imagined Continent.
European explorers had already been to the Pacific, but most had stayed further north, in areas with warmer waters and useful trade winds. Alexander Dalrymple, a scientist, geographer and explorer, urged that a voyage to find the Great Southern Continent should take place, and soon, before anyone else found it first. The Admiralty agreed, but was reluctant to actually commit to such a voyage. They were afraid that ships on such a journey would run into trouble with other nations, such as the French and the Dutch, who were also planning expeditions, or with countries that traded on the route the British expedition would need to take.
When the Admiralty heard about the Royal Society¡¦s plans to send a ship to observe the transit of Venus from the south Pacific, it seemed to be a perfect solution. They could hide their territorial ambitions behind the scientific mission. The Royal Society also had a strong interest in exploration to expand knowledge of the world, and so agreed to a joint voyage.
In order to secure funding for the expedition, the President of the Royal Society, the Earl of Morton, petitioned King George III, who readily agreed to fund the trip. He was very interested in science and had a new observatory built at Kew, where he and Queen Charlotte made their own observations of the 1769 Transit. James Cook was chosen to lead the expedition. Cook was acceptable to both the Royal Society and the Admiralty, having proven himself as an excellent sailor, navigator, chart maker and astronomer. He had recorded an eclipse of the Sun and submitted a paper on his observations to the Royal Society.
A vessel was chosen and renamed the Endeavour. As well as the usual provisions, the Royal Society supplied the ship with two state of the art astronomical telescopes. Other scientific instruments included a portable observatory, an astronomical clock, and a theodolite.
Another facet to the Royal Society¡¦s involvement in Cook¡¦s first voyage was the inclusion of a Fellow of the Society, Joseph Banks. Twenty-five-year-old Banks was not only extremely rich, but also had a very keen interest in natural history. A place on Cook¡¦s voyage would provide him with a perfect opportunity to collect and study specimens that were completely new to science, and would also give him the opportunity he sought to travel. Traditionally, wealthy young men of the time seeking adventure would go on a trip around Europe, an option that Banks scorned. ¡§Every blockhead does that¡¨ he is said to have remarked, ¡§my Grand Tour shall be one around the whole globe¡¨.
Banks managed to secure himself a position on the voyage and paid handsomely for the privilege. To accompany him, he brought a party of eight staff, including naturalists to help him with his collecting, artists to draw what he found, and a number of assistants and servants. He took scientific equipment, including devices for catching and storing specimens, two of his pet dogs, and a complete library of books. As it happens, his inclusion in the voyage was an extremely good decision, as he ended up contributing an enormous amount to the scientific knowledge of the time, both on the journey, and when he returned.
The Endeavour began its voyage on 25 August 1768. Cook was given strict instructions by the Earl of Morton as to how the people of the lands that he and his crew encountered should be treated. With a sympathy that was all too rare at the time, he was told to ¡§exercise the utmost patience and forbearance¡¨ when dealing with the native people they met. ¡§They are the natural and in the strictest sense of the word, the legal possessors of the several regions they inhabit.¡¨ he was told. ¡§No European Nation has a right to occupy any part of their country, or settle among them without their voluntary consent¡¨.
Cook took these instructions to heart, and did indeed treat the people he encountered with a level of respect and fairness that was unusual at the time. He also passed these instructions on to his crew, ordering them to ¡§endeavour by every fair means to cultivate a friendship with the Natives and to treat them with all imaginable humanity¡¨.
After sailing around South America and into the Pacific, the Endeavour arrived in Tahiti on the 13th of April, 1769. Cook and his astronomer Charles Green immediately busied themselves making preparations for their observation of the transit of Venus. They chose a suitable location and carefully set up their portable observatory, even going to the trouble of building a fort around it in case their equipment was stolen. On the advice of the Earl of Morton, additional observation posts to the west and east were also set up, to increase their chances of a successful result.
The date that the transit was due to take place (3rd of June) duly arrived, and luckily, the weather was absolutely perfect. When the actual observation of Venus passing across the face of the sun began however, the observers soon realized they had struck a rather serious problem that they had not expected. To their consternation, Cook and his team found that the edge of the planet blurred with that of the sun in the so-called ¡§oil drop effect¡¨, making it very difficult to determine precisely when the transit actually began and ended. The result of this problem was that each of the observers at Tahiti had a slightly different opinion as to how long the transit actually took.
Observers in other places experienced the same problem. Over 600 papers were ultimately delivered to scientific bodies giving a value for the solar parallax. By eliminating inadequate or suspect data, they narrowed down the range to 8.43 to 8.80 seconds. This corresponded to a distance of 90 to 94 million miles (145-151 million kilometers). ¡§Typical of the more discriminating analyses was that presented to the Royal Society in December 1771 by Thomas Hornsby, Savilian Professor of Astronomy at Oxford University. Hornsby used the observations from just five locations: Vardo, in Lapland (Father Maximilian Hell); the Kola Peninsula, between the Arctic Ocean and the White Sea (Stepan Rumovsky); Hudson¡¦s Bay (Joseph Dymond and William Wales); California (Jean Chappe d¡¦Auteroche); and Tahiti (James Cook and Charles Green).
¡§On this basis he derived a solar parallax, at the time of transit, of 8.65, the mean parallax will be found to be =8.78;¡K¡¨ƒ¡ From this, Hornsby deduced an Earth-Sun distance of 93,726,900 miles (151 million kilometers), remarkably close to today¡¦s accepted value of 150 million kilometers.
So whilst Cook and Green were disappointed with the imprecision of their Transit observations, combined with those of other observers, their results were valuable. The Endeavour voyage turned out to be an outstanding scientific success, particularly in the area of natural history. This was thanks largely to the efforts of Joseph Banks and his entourage, who returned from the journey with about 30,000 specimens of plants, 1,000 animal specimens, and a large number of exquisite drawings. This priceless collection, and his library, are now stored in the British Museum of Natural History in London.
Although Cook went on to make two more expeditions to the Pacific, Banks never went on another voyage. He had initially planned on joining Cook¡¦s second journey, but problems arose when he insisted on taking an even more extravagant entourage than on the first voyage. He ordered that accommodation be built atop the Resolution for him and his party, but it was soon apparent that the superstructure had completely destabilized the vessel. It had to be removed and Banks simply refused to take part in the journey. This proved to be the end of his travels.
Banks spent the rest of his life extremely productively, contributing to and promoting a variety of scientific endeavours. Banks was elected president of the Royal Society in 1778, a position he retained for thirty-two years until his death in 1820, making him the longest serving president of the Royal Society to date.
As a result of the scientific success of his voyages, Cook himself was elected a Fellow of the Royal Society in 1776, and in that same year, he was awarded the Society¡¦s prestigious Copley medal. The premier award of the Royal Society, the Copley Medal is awarded annually for outstanding achievements in any branch of science. In more recent times, it has been given to such eminent scientists as Charles Darwin and Albert Einstein. Cook was given the award in recognition of his numerous scientific accomplishments, including undertaking voyages to new lands, surveying new coastlines, dispelling the illusion of the great southern continent, and in particular, the innovative new methods he used to preserve the health of his crew.
