The length of the road, of which scattered fragments only remain, is variously estimated, from fifteen hundred to two thousand miles; and stone pillars, in the manner of European milestones, were erected at stated intervals of somewhat more than a league, all along the route. Its breadth scarcely exceeded twenty feet.41 It was built of heavy flags of freestone, and in some parts, at least, covered with a bituminous cement, which time has made harder than the stone itself. In some places, where the ravines had been filled up with masonry, the mountain torrents, wearing on it for ages, have gradually eaten a way through the base, and left the superincumbent mass--such is the cohesion of the materials--still spanning the valley like an arch ! 42Over some of the boldest streams it was necessary to construct suspension bridges, as they are termed, made of the tough fibres of the maguey, or of the osier of the country, which has an extraordinary degree of tenacity and strength. These osiers were woven into cables of the thickness of a man's body. The huge ropes, then stretched across the water, were conducted through rings or holes cut in immense buttresses of stone raised on the opposite banks of the river, and there secured to heavy pieces of timber. Several of these enormous cables, bound together, formed a bridge, which, covered with planks, well secured and defended by a railing of the same osier materials on the sides, afforded a safe passage for the traveller. The length of this aerial bridge, sometimes exceeding two hundred feet, caused it, confined, as it was, only at the extremities, to dip with an alarming inclination towards the centre, while the motion given to it by the passenger occasioned an oscillation still more frightful, as his eye wandered over the dark abyss of waters that foamed and tumbled many a fathom beneath. Yet these light and fragile fabrics were crossed without fear by the Peruvians, and are still retained by the Spaniards over those streams which, from the depth or impetuosity of the current, would seem impracticable for the usual modes of conveyance. The wider and more tranquil waters were crossed on balsas--a kind of raft still much used by the natives--to which sails were attached, furnishing the only instance of this higher kind of navigation among the American Indians.43The other great road of the Incas lay through the level country between the Andes and the ocean. It was constructed in a different manner, as demanded by the nature of the ground, which was for the most part low, and much of it sandy. The causeway was raised on a high embankment of earth, and defended on either side by a parapet or wall of clay; and trees and odoriferous shrubs were planted along the margin, regaling the sense of the traveller with their perfumes, and refreshing him by their shades, so grateful under the burning sky of the tropics. In the strips of sandy waste, which occasionally intervened, where the light and volatile soil was incapable of sustaining a road, huge piles, many of them to be seen at this day, were driven into the ground to indicate the route to the traveller.44All along these highways, caravansaries, or tambos, as they were called, were erected, at the distance of ten or twelve miles from each other, for the accommodation, more particularly, of the Inca and his suite, and those who journeyed on the public business. There were few other travellers in Peru. Some of these buildings were on an extensive scale, consisting of a fortress, barracks, and other military works, surrounded by a parapet of stone, and covering a large tract of ground. These were evidently destined for the accommodation of the imperial armies, when on their march across the country. The care of the great roads was committed to the districts through which they passed, and a large number of hands was constantly employed under the Incas to keep them in repair.
This was the more easily done in a country where the mode of travelling was altogether on foot; though the roads are said to have been so nicely constructed, that a carriage might have rolled over them as securely as on any of the great roads of Europe.45 Still, in a region where the elements of fire and water are both actively at work in the business of destruction, they must, without constant supervision, have gradually gone to decay.
