north behind a high chain of near hills, and is evidently a very small and short stream. Up to Último rancho the rocks are argillaceous; but near the source of the Chicapa, compact and blue limestones abound, which grow coarser as we ascend to the Arroyo Providencia.
This stream runs through a deep canon, two or three hundred feet high, and its precipitous sides are covered with overhanging stalactites.
We also found quite a large deposit of nitrate of potassa about two miles east of Scarce's rancho. After four days' travel we ascended to a high spot, where the underbrush ceases to grow.
We then ascertained that we had followed the lowest valley, which leads directly to the gap between the highest point of the Sierra and the Atravesado Peak; in other words, we had followed the valley supposed by Moro to be the bed of the Chicapa River. A reconnoissance from a high point advised us to leave Providencia Brook, which had become impossible to ascend, for another more southerly and marked valley, which was named Aguas Nuevas, in commemoration of the day, January 1, 1871. When we struck it, at 7 a. m., our height was 1,375 feet above Chivela, and at 4 p. m. our elevation was 3,245 feet. Feeling convinced beyond any possible doubt that this was the lowest thalweg within five miles from north to south, I determined to leave its bed, and see how the country looked east of us, or toward the Ostuta. Ten minutes up-hill travel brought us to a cleared eminence, from which I saw, with a feeling of disappointment I cannot describe, that the chances of bringing a feeder through this route were very few, because our height was so great, and the Ostuta, running from north to south, had to descend an astonishing distance, in order to make a junction of these rivers possible, since the Pacific plains reached to our latitude, and from this point northward the mountains rise abruptly from the plains. I hoped that our labor might still bear some fruit, because, turning to page 11 of Señor Moro's original report, in my possession, entitled 'Reconocimiento del Istmo de Tehuantepec, London, June 1, 1844,' I read the following words, which I translate. Señor Moro, standing on the Atravesado Mountain, says: 'Toward the north I saw the deep ravine through which the Chicapa runs; and on the east the high lands of the Ostuta's bed, which I had just visited and recognized perfectly, were less than three miles off. The difference of level between the two points is so inconsiderable that there is no doubt as to the possibility of effecting the junction of these rivers. And it is no less evident that there is not the least obstacle to prevent it, in the short distance intervening between them." Filled with hope at this precise statement, although very short of provisions, and with the Indians who accompanied us very discontented and rebellious, I turned to the south-east, in order to ascend the Atravesado. Failing to see from the Atravesado anything in the direction of the Ostuta, on account of an intervening mountain, we moved south and then east, in order to descend by a detour to the most south-easterly spur of the Atravesado.
With the exception of the high point just abandoned on the south, everything else east or north of us appeared under our feet; and had it been possible to see the high land of the Ostuta from any point of this mountain, this was the place from which to view it. The highest part of the sierra bears
