Fifth.--The pass of the Cumbre by Uspallata, the road most usually taken by travellers proceeding from Mendoza to Santiago de Chile, and which has been very particularly described by several Englishmen, who have gone that way. Of the published accounts that of Mr. Miers is, perhaps, the best, as he had the most opportunities of making it so, having crossed it no less than four times, once with his wife, who was taken in labour upon the road. Lieutenant Brand's is particularly interesting, from his having crossed at the season when the Cordillera was covered with snow, which obliged him to proceed on foot a great part of the way, and to encounter fearful risks, which he has very graphically described. The whole distance from Mendoza to Santiago is 107 post leagues; and the highest part of the Andes crossed is (by barometrical measurement), according to Dr. Gillies, 12,530 feet above the sea:--Mr. Miers says about 600 feet less. From the commencement of November to the end of May, occasionally a few weeks sooner or later, this road is passable the whole distance on mules:--for the rest of the year it is generally closed to all but foot-passengers, and the crossing is then attended with considerable danger; many lives have been lost in attempting it. A striking object on this road is the splendid arch called the Inca's Bridge, seventy-five feet over, which nature has thrown across a ravine one hundred and fifty feet deep, through which runs the river of Las Cuevas. There are natural hot springs about it, which some persons suppose to have contributed to its formation:--it is evident, however, that some infinitely more powerful agency has been at work, from the appearance of beds of fossil shells there at an elevation of 8650 feet above the level of the present sea. Sixth.--About half way over, near the station called the Punta de las Vacas, a road branches off to the valley of Tupungato, and afterwards crosses the Cordillera to the north of the peak so called, descending on the opposite side into Chile by the valley of the little river Dehesa, from which it is called the Dehesa Pass: it is very little used. Seventh.--South of the mountain of Tupungato is the Portillo Pass, which falls into the valley of the river Maypú in Chile with the Rio del Yeso. By many travellers it is preferred to the high road by Uspallata, being the shorter way of the two by twenty leagues:--it is, however, seldom open longer than from the beginning of January to the end of April, the greater elevation of that part of the Cordillera causing it to be longer blocked up by the snow.