Voyage Historique de l'Amérique Méridionale: Fait par Ordre du Roi d'Espagne
In 1734, King Philip V of Spain asked Spanish mathematician, scientist and mariner Jorge Juan and scientist, author and astronomer Antonio de Ulla to join the French Geodesic Mission in measuring the length of a degree of meridian arc at the Equator. The mission was to determine the roundness of the Earth. Ulloa later published an account of the people and sights they encountered. Shown here is a triple rainbow seen after the eruption of Mount Cotopaxi.