Between Captain Cook and Mauna Kea: The British 1874 Transit of Venus Expedition to Hawaii
Michael Chauvin
An illustrated lecture delivered at the Smithsonian Institution
in Washington, D.C., on June 7, 2004
Introduction
The beginning of modern astronomy in Hawaii can be dated to the arrival, in 1778, of the British explorer Captain James Cook (Fig. 1). In addition to being supplied with state-of-the-art navigational instruments – including the sextant and the chronometer – Cook also carried, on each of his two ships, the Resolution and the Discovery, a portable astronomical observatory (Fig. 2) designed by the astronomer William Bayly. Very much like the modern observatories that now populate the summit of Mauna Kea, Bayly’s observatory sheltered a telescope and a clock and was equipped with a revolving dome that could be opened and closed at will. With these astronomical aids at his command, Cook was able to do what no one prior to his time had ever done: He was able to assign the to islands a latitude and a longitude, and thus to place Hawaii on a map (Fig. 3). 
Observations of Jupiter’s satellites, for example, helped to fix the longitude of Kealakekua Bay for the first time in history; and as the distance between the Prime Meridian at Greenwich and a tropical island paradise became as firmly defined as the science of the day would allow, a British presence became firmly established in Hawaii.Captain Cook was killed in 1779 at this very location, Kealakekua Bay – a place to which I shall return later in my story. Ten years earlier, his first Pacific voyage had taken him into the South Pacific where, in June of 1769, he had observed, from the island of Tahiti, a rare transit of the planet Venus across the sun.
At Tahiti, a temporary garrison called Fort Venus (Fig. 4) provided a safe haven for Cook’s men and their instruments and the transit was observed under sunny skies. But, just as importantly, many of the elements of this pioneering eighteenth-century enterprise – the passing of a planet in front of the sun, the demonstration of British naval and navigational prowess, the transport of observers and equipment to a remote Pacific island, and the construction of a temporary fortress – proved a good rehearsal for what was to occur in Hawaii more than 100 years later.When, in 1874, Venus again slithered across the sun, the British were once more active in the Pacific, and Hawaii, where British cultural influences were by then easily recognizable, was very much at the center of the enterprise. Cook’s three voyages of exploration, including his voyages to Tahiti and Hawaii – and, in particular, the astronomy that had informed those voyages – had set the stage for even more ambitious endeavors.
Not long after Cook’s arrival in Hawaii, the islands were united under a single ruler, Kamehameha the Great, and soon thereafter adopted for their government a European-styled monarchy. By the latter half of the nineteenth century, Hawaii had been ruled by a succession of hereditary chiefs, or ali‘i, and was still an independent kingdom when, on September 9, 1874, nearly a century after Captain Cook had appointed Hawaii a position on a map, a ship from England, HMS Scout, sailed into Honolulu Harbor carrying an expedition of seven astronomers (Fig. 5).
The mission of the expedition was – as Captain Cook’s had been in 1769 – to observe a rare transit of Venus across the sun for the purpose of better determining the value of the Astronomical Unit (Fig. 6) – that is, the Earth-sun distance – and thereby the absolute scale of the solar system. For although Copernicus had, by the 16th century, put the known planets in their correct order and had derived from his model of the solar system a set of relative distances among its members, their absolute distances remained hostage to the uncertain value of the Astronomical Unit (AU). Astronomers still needed a celestial yardstick of known length to measure distances among the planets and to link the planets to the stars beyond.The circumstances of a transit of Venus and its relationship to the Astronomical Unit are, I shall assume, well known to people in this room and need not detain us here. They form the subject matter of a fine exhibition now on display here at the Smithsonian Institution, and the American participation in the transit observations of the nineteenth century is retold in the exhibit. But because Hawaii was still an independent kingdom at that time, and not an American state until 1959, it is my task today to tell you something about Hawaii’s role at the center of an international effort to solve what was once considered the most important problem in observational astronomy.
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Robert J. Havlik, Librarian Emeritus
