Chasing Venus with Andrea Wulf, 29-30 May

Historian Andrea Wulf will speak about her new book, Chasing Venus: The Race to Measure the Heavens, at two local sites next week. On Tuesday, 29 May, she’ll talk to the Lexington Historical Society at 7:30 P.M. That event will take place in the Lexington Depot, and is free.

The next evening at 7:00, Wulf will speak at the Arnold Arboretum—an appropriate locale since her previous books include Brother Gardeners and Founding Gardeners, about horticulture in the eighteenth century. This talk will cost $10 for Massachusetts Historical Society and Arnold Arboretum members or fellows, $20 for others, and pre-registration is required (call 617-384-5277). Wulf will speak in the Weld Hill Research Building. (Boston 1775 readers may recall that Weld Hill was our best guess for the location of the Continental Army’s fallback position in the summer of 1775.)

Chasing Venus describes the international scientific endeavor to observe the transit of Venus in 1761 and 1769, as predicted decades earlier by astronomer Edmund Halley. On those occasions the planet moved in front of the Sun, appearing as a small black dot against the light.

Earlier this spring the Boston Globe’s review of Chasing Venus described the scientists’ efforts:

The obstacles confronting the platoon of observers were formidable. Britain and France were at war, but this did not deter fellow astronomers from linking up with each other. Indeed, a Frenchman, Joseph-Nicolas Delisle, took the lead. With contacts in Amsterdam, Basel, Florence, Vienna, and St. Petersburg, Delisle was a whirlwind planner and a hub of scientific back and forth. A skilled surveyor, his “mappemonde,” which highlighted the best spots around the globe to glimpse the transit, became an essential document for astronomers.

The theory of the transit was fine and good, but setting up the viewing stations proved a challenge. Getting to far-flung locations was dangerous work. For the 1761 transit, the British sent a man to St. Helena island, a tiny isolated speck in the south Atlantic. A colleague of Delisle’s, Jean-Baptiste Chappe d’Auteroche trekked 4,000 miles from Paris to the depths of Siberia, only to be attacked by villagers who thought his fancy scientific instruments had magical powers: They blamed him for bringing on devastating floods. Two British fellows named [Charles] Mason and [Jeremiah] Dixon (surveyors of the famous line) were nearly smashed to bits by a French warship as they attempted to get to Sumatra. They nearly quit in fear and frustration.

But surely the most star-crossed (literally) of the Venus observers was the extravagantly named Frenchman Guillaume Joseph Hyacinthe Jean-Baptiste Le Gentil de la Galaisière. His name notwithstanding, Le Gentil’s odyssey would be anything but nice. His was a story of tragic near misses. For the 1761 transit, Le Gentil was to journey to Pondicherry, then a French possession in India. War got in the way — the British laid siege to the town, and Le Gentil instead went to Mauritius, where he was waylaid by dysentery. On June 6, the day of transit, he was on a rolling ship, and he could not get an accurate fix on the planet. Eight years later, he made it back to Pondicherry for the 1769 transits, but weather marred the viewing. Poor Le Gentil had come so far “only to be the spectator of a fatal cloud.”

Wulf’s book and talk are timely because there will be a transit of Venus visible in Massachusetts on 5-6 June—assuming the weather cooperates. The Harvard Observatory has set up a viewing time for the public on the evening of 5 June.

TOMORROW: A Massachusetts scientist in 1761.