The load, which is termed a carga, was generally three hundred pounds. Two arrieros, or packers, place the goods on the mule's back, one, the cargador, standing on the near side, his assistant on the other. The carga is then hoisted on top of the saddle if it is a single package; or if there are two of equal size and weight, one on each side, coupled by a rope, which balances them on the animal. Another stout rope is then thrown over all, drawn as tightly as possible under the belly, and laced round the packs, securing them firmly in their place. Over the load, to protect it from rain, is thrown a square piece of matting called a petate. Sometimes, when a mule is a little refractory, he is blindfolded by a thin piece of leather, generally embroidered, termed the tapojos, and he remains perfectly quiet while the process of packing is going on. When the load is securely fastened in its place, the blinder is removed. The man on the near side, with his knee against the mule for a purchase, as soon as the rope is hauled taut, cries out "Adios," and his assistant answers "Vaya!" Then the first says again, "Anda!" upon which the mule trots off to its companions, all of which feed around until the animals of the whole train are packed. It seldom requires more than five minutes for the two men to complete the packing of the animal, and in that time is included the fastening of the aperejo. It is surprising to note the degree of skill exercised by an experienced packer, and his apparently abnormal strength in handling the immense bundles that are sometimes transported. By the aid of his knees used as a fulcrum, he lifts a package and tosses it on the mule's back without any apparent effort, the dead weight of which he could not move from the ground. An old-time atajo or caravan of pack-mules generally numbered from fifty to two hundred, and it travelled a jornado, or day's march of about twelve or fifteen miles. This day's journey was made without any stopping at noon, because if a pack-mule is allowed to rest, he generally tries to lie down, and with his heavy load it is difficult for him to get on his feet again. Sometimes he is badly strained in so doing, perhaps ruined forever. When the train starts out on the trail, the mules are so tightly bound with the ropes which confine the load that they move with great difficulty; but the saddle soon settles itself and the ropes become loosened so that they have frequently to be tightened. On the march the arriero is kept busy nearly all the time; the packs are constantly changing their position, frequently losing their balance and falling off; sometimes saddle, pack, and all swing under the animal's belly, and he must be unloaded and repacked again.