Many of the hills, though covered with a strong soil, were too precipitous to be tilled. These they cut into terraces, faced with rough stone, diminishing in regular gradation towards the summit; so that, while the lower strip, or anden, as it was called by the Spaniards, that belted round the base of the mountain, might comprehend hundreds of acres, the upper-most was only large enough to accommodate a few rows of Indian corn.21 Some of the eminences presented such a mess of solid rock, that, after being hewn into terraces, they were obliged to be covered deep with earth, before they could serve the purpose of the husbandman. With such patient toil did the Peruvians combat the formidable obstacles presented by the face of their country! Without the use of tools or the machinery familiar to the European, each individual could have done little; but acting in large masses, and under a common direction, they were enabled by indefatigable perseverance to achieve results, to have attempted which might have filled even the European with dismay.22In the same spirit of economical husbandry which redeemed the rocky sierra from the curse of sterility, they dug below the arid soil of the valleys, and sought for a stratum where some natural moisture might be found. These excavations, called by the Spaniards hoyas, or "pits," were made on a great scale, comprehending frequently more than an acre, sunk to the depth of fifteen or twenty feet, and fenced round within by a wall of adobes, or bricks baked in the sun. The bottom of the excavation, well prepared by a rich manure of the sardines,--a small fish obtained in vast quantities along the coast,--was planted with some kind or grain or vegetable.23The Peruvian farmers were well acquainted with the different kinds of manures, and made large use of them; a circumstance rare in the rich lands of the tropics, and probably not elsewhere practised by the rude tribes of America. They made great use of guano, the valuable deposit of sea-fowl, that has attracted so much attention, of late, from the agriculturists both of Europe and of our own country, and the stimulating and nutritious properties of which the Indians perfectly appreciated.

This was found in such immense quantities on many of the little islands along the coast, as to have the appeaarnce of lofty hills, which, covered with a white saline incrustation, led the Conquerors to give them the name of the sierra nevada, or "snowy mountains."The Incas took their usual precautions for securing the benefits of this important article to the husbandman. They assigned the small islands on the coast to the use of the respective districts which lay adjacent to them.