In running, we incline the body more, and so, as it were, fall faster. When we walk, one foot is on the ground all the time, and there is an instant when both feet are planted upon it; but in running there is an interval of time in each step when both feet are off the ground, and the body is wholly unsupported. As we step alternately with the feet, we are inclined to turn the body first to one side and then to the other. This movement is sometimes counterbalanced by swinging the hand on the opposite side. [Footnote: In ordinary walking the speed is nearly four miles an hour, and can be kept up for a long period. But exercise and a special aptitude for it enable some men to walk great distances in a relatively short space of time. Trained walkers have gone seventy-five miles in twenty hours, and walked the distance of thirty-seven miles at the rate of five miles an hour. The mountaineers of the Alps are generally good walkers, and some of them are not less remarkable for endurance than for speed. Jacques Balmat, who was the first to reach the summit of Mont Blanc, at sixteen years of age could walk from the hamlet of the Pélerins to the mountain of La Côte in two hours,--a distance which the best- trained travelers required from five to six hours to get over. At the time of his last attempt to reach the top of Mont Blanc, this same guide, then twenty years old, passed six days and four nights without sleeping or reposing a single moment. One of his sons, Édouard Balmat, left Paris to join his regiment at Genoa; he reached Chamouni the fifth day at evening, having walked three hundred and forty miles. After resting two days, he set off again for Genoa, where he arrived in two days. Several years afterward, this same man left the baths at Louèche at two o'clock in the morning, and reached Chamouni at nine in the evening, having walked a distance equal to about seventy-five miles in nineteen hours. In 1844, an old guide of De Saussure, eighty years old, left the hamlet of Prats, in the valley of Chamouni, in the afternoon, and reached the Grand-Mulets at ten in the evening; then, after resting some hours, he climbed the glacier to the vicinity of the Grand Plateau, which has an altitude of about thirteen thousand feet, and then returned to his village without stopping.--_Wonders of the Body_.]