In February, 1800, the travellers traced the water system of the Orinoco, often in the midst of danger. Once, in a severe storm, their boat was two-thirds full of water. "Our position," says Humboldt, "was truly appalling; the shore was distant from us more than a mile, where a number of crocodiles could be discerned lying half out of the water. Even if we had gained the shore against the fury of the waves and the voracity of the crocodiles, we should infallibly have either perished from hunger or been torn in pieces by the tigers, for the woods upon these shores are so dense and so intertwined with lianas as to be absolutely impenetrable. The strongest man, axe in hand, could hardly make his way in twenty days for the distance of a league. The river too is so little frequented that even an Indian canoe scarcely passes oftener than once in two months. At this most momentous and perilous crisis a gust of wind filled the sails of our little vessel and effected in a marvellous manner our deliverance." To his botanist friend, Willdenow, he writes:--"During four months of this journey we passed the night in forests, surrounded by crocodiles, boa constrictors, and tigers, which are here bold enough to attack a canoe, while for food we had nothing better than rice, ants, bananas, and occasionally the flesh of monkeys, with only the waters of the Orinoco wherewith to quench our thirst. Thus have we with difficulty toiled, our hands and faces swollen with mosquito bites, from Mondvaca to the volcano of Duida, from the limits of Quito to the frontier of Surinam--through tracts of country extending over twenty thousand square miles, in which no Indian is to be met with, and where the traveller encounters only apes or serpents. "In Guiana the mosquitoes abound in such clouds as to darken the air, and, as it is absolutely necessary to keep head and hands constantly covered, no writing can be done by daylight; the intolerable pain produced by the attacks of these insects renders it impossible to hold the pen steadily. All our work had therefore to be carried on by the light of a fire, in an Indian hut, where no ray of sunlight could penetrate, and into which we had to creep on our hands and knees. Here, if we escaped the torment of the mosquitoes, we were almost choked by the smoke. At Maypures, we and the Indians took refuge in the midst of the cascade, where the spray from the foaming stream kept off the insects. At Higuerote, the people are accustomed at night to lie buried three or four inches deep in sand, with only the head exposed." Sometimes twenty-four Indians were in Humboldt's employ for months together, and fourteen mules were required to carry his instruments and plants.