Transits, Travels and Tribulations, III
The abbé Le Gentil was another who would pursue both transits. Indeed, his 11-year odyssey would rank as the longest astronomical expedition in history. Despite a contemporary saying of him that "his face did not prejudice one in his favor," at 28 Le Gentil was a well-trained astronomer. By 1753 he had made his own calculations of the transits and had volunteered to go to Pondichery in India to observe the June 6, 1761 event. He sailed from Brest in a French man-of-war in March 1760, allowing himself plenty of time to sail around southern Africa and across the Indian Ocean. Most of this trip was "uneventful, save for the loss of a fellow passenger by suicide and by the pursuit by an English fleet off the Cape of Good Hope." Arriving at Isle de France (Mauritius) in July 1760, however, he discovered that Pondichery was besieged by the British, and that a French force sent by sea to raise the siege had been all but destroyed by a hurricane while en route. A second force arrived after a delay of eight months, and Le Gentil accompanied it on its attempt to relieve the beleaguered Pondichery. Winds were contrary, however ("we wandered around for five weeks in the seas of Africa"), and by the time the fleet arrived off the Malabar Coast only two weeks before the transit, they discovered that the British had captured and consolidated themselves in Pondichery. Le Gentil's ship was lucky to elude the British naval squadrons and immediately headed back the 5,000 kilometers or so to Isle de France. In mid-ocean on June 6, under a cloudless sky, Le Gentil had a perfect view of Venus transiting across the sun's disk. But since precise timing of the event was essential, and his pendulum clocks useless at sea, the view was of no scientific value at all.
Rather than go home empty-handed, Le Gentil wrote to the Académie Royale des Sciences in Paris suggesting that he spend a year or so exploring the islands of the Indian Ocean, carrying out work in natural history, geography, navigation and more or less anything that might be useful. This was agreed to, and soon Le Gentil was busy mapping the east coast of Madagascar. Here he made the mistake of eating the local beef, which though "rich" caused "a sort of violent stroke, of which several copious blood-lettings made immediately on my arm and my foot, and emetic administered twelve hours afterwards, rid me quite quickly." The accompanying double-vision took somewhat longer.