On the great mountain trails their feats of endurance are almost of a marvelous character. The semi-civilized are often employed as couriers, mail carriers, etc., and in all cases they invariably make from three to five times the distance covered by the whites in the same time, while there is no known domesticated animal that can possibly keep pace with them in the mountains. It takes six or seven hours of fairly continuous climbing to make, by mule-back, from the mine in a deep gulch to the "cumbra," or crest of the Barranca del Cobre, by a most difficult mountain trail, the ascent made being five thousand to six thousand feet. It takes four hours to descend in the same way. A message was sent from "la cumbra" by a Tarahumari foot runner to a person at the mine and an answer received in an hour and twenty minutes, the same messenger carrying the letter both ways, or making the round trip. One day a Tarahumari carrier passed us just after we had gone into camp about three o'clock in the afternoon, bound for the same point we expected to reach in three days' hard travel by mule-back. I wanted to send a message by him to this place, and on ascertaining when he would reach it was, as my hearers will easily infer, somewhat astonished to find out that he expected to make it that night, and I was afterward informed that he had done so. Not a great many years ago the mail from Chihuahua to Batopilas was carried by a courier on his back, who made the distance over the Sierra Madre range, a good 250 miles, and return, or a total of 500 miles, in six days. Here he rested one day and repeated his trip, his contract being for weekly service. Alongside of this the best records ever made in the many six days' "go-as-you-please" contests that are heard of in the great cities of the United States sink into almost contemptible insignificance. I could give a dozen other instances, but these are enough. Of course these runners make many "cut offs" from the established mule trails when their course is along them, and they thus save distance, but making all such allowance their endurance is still phenomenal. CHAPTER VI. THROUGH THE SIERRA MADRES--ON MULE-BACK WESTWARD FROM CARICHIC. As our next month was passed on mule-back, and Mexican mule-back at that, I think it would be not at all inappropriate to make a brief dissertation on this kind of brute for the necessary merits and demerits of the journey.