The occupations of our travellers were much disturbed during the first weeks of their abode at Cumana by the intrusion of persons desirous of examining their astronomical and other instruments. They however determined the latitude of the great square to be 10° 27′ 52″, and its longitude 66° 30′ 2″.

On the 17th of August, a halo of the moon attracted the attention of the inhabitants, who viewed it as the presage of a violent earthquake. Coloured circles of this kind, Humboldt remarks, are much rarer in the northern than in the southern countries of Europe. They are seen more especially when the sky is clear and the weather settled. In the torrid zone they appear almost every night, and often in the space of a few minutes disappear several times. Between the latitude of 15° N. and the equator he has seen small haloes around the planet Venus, but never observed any in connexion with the fixed stars. While the halo was seen at Cumana, the hygrometer indicated great humidity, although the atmosphere was perfectly transparent. It consisted of two circles; a larger, of a whitish colour, and 44° in diameter, and a smaller, displaying all the tints of the rainbow, and 1° 43′ in diameter. The intermediate space was of the deepest azure.

Part of the great square is surrounded with arcades, over which is a long wooden gallery, where slaves imported from the coast of Africa are sold.