French astronomer Guillaume Le Gentil sailed from Paris in 1760 for Pondichéry (Puducherry) in India to observe the transit of Venus on June 6, 1761.
On the way, he stopped off at Île de France (Mauritius) and learned of the war that had broken out with the English in the intervening months. They had colonized Pondichéry and so he changed his destination for the more easterly isle of Rodrigues.
But en route, the captain of the frigate he was travelling aboard became wary of the escalating crisis, and performed an about-face, heading back to Mauritius.
Le Gentil was still at sea when the transit of Venus happened and due to the motion of the boat and lack of an accurate timepiece he was unable to carry out any meaningful measurements, despite perfect weather. The astronomer was too embarrassed to return home and resolved instead to remain on Île de France, using it as a base from which to scout the Indian Ocean for appropriate observation posts for the 1769 transit.
After spending some time mapping the eastern coast of Madagascar, he decided to record the transit from Manila in the Philippines. Encountering hostility from the Spanish authorities there, however, he headed to Pondichéry, which had been restored to France in 1763. He arrived in March 1768 and built a small observatory where he waited patiently.
At last, the day of the transit – June 4, 1769 – arrived, but although the mornings in the preceding month had all been clear, on this day the sky was overcast, and Le Gentil saw nothing. The misfortune drove him to the brink of insanity, but at last he recovered enough strength to return to France.
The return trip was first delayed by dysentery, and further when his ship was caught in a storm and dropped him off at Île Bourbon (Réunion), where he had to wait until a Spanish ship took him home.
He finally arrived in Paris eleven years later in October 1771, only to find that he had been declared legally dead and been replaced in the Royal Academy of Sciences. His wife had remarried, and all his relatives had “enthusiastically plundered his estate”.
But it wasn’t all misfortune for Le Gentil. He eventually got back his seat in the academy, remarried, and apparently lived happily for another 21 years. His story was also dramatized (with some artistic licence) in Transit of Venus, a 1992 play by Canadian playwright Maureen Hunter, pictured above.