Research & Article

The Jesuits as part of their conversion strategy sought to impress royal courts and nobles with their mathematical and astro- nomical knowledge. The first French Jesuits to come to Siam in 1685 were on their way to China for this purpose. They profited from a lunar eclipse to demonstrate their science to King Narai. One of their number, Tachard, instead of going to China returned to France and brought back in 1687, supposedly at King Narai’s re- quest, fourteen more mathematical Jesuits, this time destined to stay in Siam. The following year they observed, separately from the king, a lunar eclipse on 16 April at a crucial juncture of events for the French in Siam, when General Desfarges had refused to advance to Lopburi to support Phaulkon in his bid to check the impending revolt of Phetracha. There was also a solar eclipse witnessed on 30 April 18 days before the coup led by Phetracha; this was witnessed by the king and the Jesuits, but only one text remarks on this.

The lunar eclipse of 1685 and the solar eclipse of 1688 were both (probably imaginatively) illustrated contemporaneously, and the contents of the collection of naïve watercolours in which the solar eclipse is found, in the Bibliothèque Nationale in Paris, are examined.