The Economist ran a feature on earlier attempts to view the “transit of Venus.” Such transits in 1761 and 1769 caused the transit of Mason, Dixon, Cook, Le Gentil, and others through remote sites in the Indian and Pacific Oceans.
Insignificant though it may seem, this rare celestial event, a “transit of Venus”, was once thought a key to understanding the universe. Two and a half centuries ago, countries dispatched astronomers on risky and expensive expeditions to observe transits from far-flung points across the globe. By doing this, they hoped to make a precise measurement of the distance to the sun and thus acquire an accurate yardstick by which the distance to everything else in the solar system could be measured….
What followed was the 18th-century equivalent of the space race. Wealthy nations took up the challenge and competed for scientific prestige. The rivalry was especially intense between Britain and France, which were engaged in the Seven Years War at the time of the transit of 1761.
Among the British expeditions was that of Charles Mason and Jeremiah Dixon, who were sent to Sumatra (and who would later achieve immortality through the name of a line they surveyed between the northern and southern American colonies). Shortly after embarking from Plymouth, eleven of their shipmates were killed during an attack by the French. Mason and Dixon wanted to cancel the voyage, but in a famously nasty note, their Royal Society sponsors warned this would “bring an indelible Scandal upon their Character, and probably end in their utter Ruin”. Faced with this, they carried on. Unfortunately their destination was captured by the French before they arrived. They ended up observing the transit from Cape Town instead.
The French had their share of troubles, too. The most pathetic of these were suffered by Guillaume Joseph Hyacinthe Jean-Baptiste Le Gentil de la Galaisiere. He was aiming for Pondicherry, a French colony in India, but he learned before arriving that it had been captured by the British. When the transit occurred, he was stuck on a pitching ship in an imprecisely known location, rendering his observations worthless. Undeterred, he decided to wait for the 1769 transit. He spent eight years on various Indian Ocean islands before making his way to Pondicherry, which had by then been returned to the French. On the day of the transit, however, it was cloudy. He then contracted dysentery, was shipwrecked, and finally returned home to find his estate looted.
By contrast, the weather was splendid in Tahiti (not then a French territory), where Venus’s path in 1769 was timed by the party of James Cook. The transit had been the main impetus for Cook’s first voyage of discovery. Once this official mission was accomplished, Cook explored the south Pacific, achieving, among other things, the first accurate maps of New Zealand and the first European awareness of Australia’s Great Barrier Reef (this was obtained the hard way, by ramming into it and nearly getting wrecked).