On arriving at the camping-ground the pack-saddles with their loads are ranged in regular order, their freight being between the saddles, covered with the petates to protect it from the rain, and generally a ditch is dug around to carry off the water, if the weather is stormy. After two or three days' travel each mule knows its own pack and saddle, and comes up to it at the proper moment with an intelligence that is astonishing. If an animal should come whose pack is somewhere else, he is soundly kicked in the ribs by the rightful mule, and sent bruised and battered to his place. He rarely makes a mistake in relation to the position of his own pack the second time. This method of transportation was so cheap, because of the low rate of wages, that wagon-freighting, even in the most level region, could not compete with it. Five dollars a month was the amount paid to the muleteers, but it was oftener five with rations, costing almost nothing, of corn and beans. Meat, if used at all, was found by the arrieros themselves. On the trail the mule-train is under a system of discipline almost as severe as that on board of a man-of-war. Every individual employed is assigned to his place and has certain duties to perform. There is a night-herder, called the savanero, whose duty it is to keep the animals from straying too far away, as they are all turned loose to shift for themselves, depending upon the grass alone for their subsistence. Each herd has a mulera, or bell-mare, which wears a bell hanging to a strap around her neck, and is kept in view of the other animals, who will never leave her. If the mare is taken away from the herd, every mule becomes really melancholy and is at a loss what to do or where to go. The cook of the party, or madre (mother) as he is called, besides his duty in preparing the food, must lead the bell-mule ahead of the train while travelling, the pack-animals following her with a devotion that is remarkable. Sometimes in traversing the narrow ledges cut around the sides of a precipitous trail, or crossing a narrow natural bridge spanning the frightful gorges found everywhere in the mountains, a mule will be incontinently thrown off the slippery path, and fall hundreds of feet into the yawning canyon below. Generally instant death is their portion, though I recall an instance, while on an expedition against the hostile Indians thirty years ago, where a number of mules of our pack-train, loaded with ammunition, tumbled nearly five hundred feet down an almost perpendicular chasm, and yet some of them got on their feet again, and soon rejoined their companions, without having suffered any serious injury.