The passage from the mouth of the Río Negro to Grand Para took only twenty to twenty-five days, so we could have gone down the Amazon as far as the Brazilian coast just as easily as returning by the Casiquiare to Caracas. We were told at San Carlos that political circumstances made it difficult to cross from Spanish to Portuguese colonies, but we did not know until our return to Europe what danger we would have been exposed to had we gone as far as Barcellos. It was known in Brazil, probably through newspapers, whose indiscretion is not helpful for travelers, that I was going to visit the Río Negro missions and examine the natural canal uniting the two river systems. In these deserted jungles the only instruments ever seen had been carried by the boundary commissioners. The Portuguese Government agents could not conceive how a sensible man could exhaust himself 'measuring lands that did not belong to him'. Orders had been issued to arrest me, seize my instruments, and especially my astronomical observations, so dangerous to the safety of the State. We were to be led along the Amazon to Grand Para, and then back to Lisbon. Fortunately, the Lisbon Government instantly ordered that I should not be disturbed but rather encouraged.

As rain was pouring down we had to sleep in the overcrowded hut. The Indians slept only from eight at night to two in the morning; the rest of the time they chatted and prepared their bitter cupana drink, poking the fire and complaining of the cold, even though the temperature was 21°C. This custom of staying awake, even of getting up four or five hours before dawn, is common to the Guiana Indians.

We had as travelling companions a Frenchman, Dr Rieux from Carcassonne, and the young son of the ill-fated Nariìo. The bad luck of these two moved us, reminding us of the state of oppression in this unhappy country. Dr Rieux, a charming, educated man, had come from Europe as doctor to Viceroy Ezpeleta. He was accused of interfering in politics, dragged out of his house in Honda in 1794, clapped in irons and taken to the inquisition prison in Cartagena. This damp place caused him a chronic blindness. For more than a year his wife had no news of his whereabouts. His belongings were dispersed and, as nothing could be proved, he was sent (bajo partido de registro) to Càdiz prison where his case would be forgotten. He managed to escape off the African coast.

The Casiquiare Indians, though easily reverting to barbaric customs, show some intelligence in the missions, work well and learn Spanish. As most missions have two or three tribes speaking different languages the language of the missionaries lets them communicate with each other. I saw a Poignave Indian talk in Castilian with a Guahibo, though both had left the jungle only three months before. Every quarter of an hour one spoke a carefully prepared phrase in which the verb, following the grammar of their own languages, was always a gerund ('When me seeing the father, the father me saying...').