Humboldt twice reached the edge of the Pinchincha crater, never before seen except by Condamine.
"I made my first trip," he says, "accompanied only by an Indian. Condamine had approached the crater by the lower part of its edge which was covered with snow, and in this first attempt I followed his example. But we nearly perished. The Indian sank to the breast in a crevasse, and we found to our horror that we were walking on a bridge of frozen snow, for a little in advance of us there were some holes through which we could see the light. Without knowing it we were in fact on the vaults belonging to the crater itself. Startled, but not discouraged, I changed my plan. From the outer rim of the crater, flung as it were upon the abyss, rise three peaks, three rocks, which are not covered with snow, because the steam from the volcano prevents the water from freezing. I climbed upon one of these rocks and on the top of it found a stone attached on one side only to the rock and undermined beneath, so as to protrude like a balcony over the precipice. This stone was but about twelve feet long by six broad, and is terribly shaken by the frequent earthquakes, of which we counted eighteen in less than thirty minutes. To examine the depths of the crater thoroughly we lay on our faces, and I do not think imagination could conceive anything drearier, more gloomy, or more awful than what we saw. The crater consists of a circular hole nearly a league in circumference, the jagged edges of which are surrounded by snow. The interior is of pitchy blackness, but so vast is the gulf that the summits of several mountains situated in it can be made out at a depth of some 300 fathoms, so only fancy where their bases must be!
"I have no doubt that the bottom of the crater must be on a level with the town of Quito. Condamine found this volcano extinct and covered with snow, but we had to take the bad news to the inhabitants of the capital, that the neighbouring burning mountain is really active."
Humboldt ascended the volcano of Antisana to a height of 2773 fathoms, but could go no further, as the cold was so intense that the blood started from the lips, eyes, and gums of the travellers. It was impossible to reach the crater of Cotopaxi.
On the 9th June, 1802, Humboldt, accompanied by Bonpland, started from Quito to examine Chimborazo and Tungurunga. The peak of the latter fell in during the earthquake of 1797, and Humboldt found its height to be but 2531 fathoms, whilst in Condamine's time it was 2620 fathoms.
From Quito the travellers went to the Amazon by way of Lactacunga, Ambato and Rio-Bamba situated in the province laid waste by the earthquake of 1797, when 40,000 inhabitants were swallowed up by water and mud. Going down the Andes, Humboldt and his companions had an opportunity of admiring the remains of the Yega road, leading from Cusco to Assuay, and known as the Inca's road. It was built entirely of hewn stones, and was very straight. It might have been taken for one of the best Roman roads. In the same neighbourhood are the ruins of a palace of the Inca Fupayupangi, described by Condamine in the minutes of the Berlin Academy.
After a stay of ten days at Cuença, Humboldt entered the province of Jaen, surveyed the Marañon as far as the Rio Napo, and with the aid of the astronomical observations he was able to make, supplemented Condamine's map. On the 23rd October, 1802, Humboldt entered Lima, where he successfully observed the transit of Mercury.
After spending a month in that capital he started for Guayaquil, whence he went by sea to Acapulco in Spanish America.
The vast number of notes collected by Humboldt during the year he spent in Mexico, and which led to the publication of his Essay on Spanish America, would, after what we have said of his previous proceedings, be enough to prove, if proof were needed, what a passion he had for knowledge, how indomitable was his energy and how immense his power of work.
At one and the same time he was studying the antiquities and the history of Mexico, the character, customs, and language of its people, and taking observations in natural history, physical geography, chemistry, astronomy, and topography.