Villariño was blamed for not exploring this river, certainly by far the most considerable affluent of the Negro. He seems to have satisfied himself with merely ascending it in a little boat for about a couple of leagues, which brought him to the place where the Indians are in the habit of crossing it, and where he doubted whether there was sufficient water at the time to allow the launches to go up, though, from the vestiges of the floods along shore, it was evidently navigable at times for much larger craft. His best excuse for not doing more was his anxiety to reach the Cordillera before the state of the snow should prevent his communicating with Valdivia. To make the best of his way onward in that direction was now his main object; but the difficulties he had as yet experienced were nothing to those which awaited him in his further progress. The horses obtained from the Indians were completely worn out, and after passing the Neuquen, the whole labour of towing the boats along again devolved upon the men. About a league above the junction of the two rivers, the latitude was found to be 38° 44´. The course of the Negro shortly afterwards was found to incline very much more to the south, apparently turned off by the prolongation of a chain of hills from the north, which equally determines the course of the Neuquen higher up, and as far as the eye can reach from the point of its junction with the Negro. Through these hills the Negro has either found, or forced a passage, which on either side is bounded by steep, rocky escarpments, rising 500 or 600 feet above it; and here the stream ran with such violence, that it was with the greatest difficulty the launches were dragged on, one by one; a difficulty further increased by the shallowness of the water, which made it necessary in many places to deepen the channel with spades and pick-axes, and to unload the boats and carry their cargoes considerable distances, before they could proceed[25]. All this caused incredible fatigue to the men, unaccustomed to such service, and supported only on the dry and salt provisions they had with them. Their legs became swelled with working for days together in the water, and they were covered with sores from the bites of the flies and mosquitos which hovered in clouds above its surface. The scurvy broke out, and some of them became seriously ill: fortunately they fell in with some apple-trees, the fruit of which was a great comfort to the sick; but the snow-capped peak of the Cerro Imperial, as well as the whole range of the Cordillera, was now in full view before them; and the hope of being soon in communication with Valdivia gave them fresh courage, and redoubled their exertions to reach their journey's end.