Balthazar had moreover heard of the marvellous system of irrigation whereby the Incas had fertilized nearly the whole of the Peruvian desert; and as he surveyed the ruins he conceived the great idea of restoring the aqueduct and repeopling the neighboring waste. To this task he devoted his life. His first proceeding was to convert the Indians and found a mission, which he called San Cristobal de Quipai; his next to show them how to make the most of the water-privileges they already possessed. A reservoir was built, more land brought under cultivation, and the oasis rendered capable of supporting a larger population. The resulting prosperity and the abbé's fame as a physician (he possessed a fair knowledge of medicine) drew other Indians to Quipai. After a while the gigantic undertaking was begun, and little by little, and with infinite patience and pain accomplished. It was a work of many years, and when I travelled the whole length of the _azequia_ I marvelled greatly how the abbé, with the means at his command, could have achieved an enterprise so arduous and vast. The aqueduct, nearly twenty leagues in length, extended from the foot of the snow-line to a valley above Quipai, the water being taken thence in stone-lined canals and wooden pipes to the seashore. In several places the _azequia_ was carried on lofty arches over deep ravines: and there were two great reservoirs, both remarkable works. The upper one was the crater of an extinct volcano, of unknown depth, which contained an immense quantity of water. It took so long to fill that the abbé, as he laughingly told me, began to think that there must be a hole in the bottom. But in the end it did fill to the very brim, and always remained full. The second reservoir, a dammed up valley, was just below the first; it served to break the fall from the higher to the lower level and receive the overflow from the crater. A bursting of either of the reservoirs was quite out of the question; at any rate the abbé so assured me, and certainly the crater looked strong enough to hold all the water in the Andes, could it have been got therein, while the lower reservoir was so shallow--the out-flow and the loss by evaporation being equal to the in-take--that even if the banks were to give way no great harm could be done. I mention these particulars because they have an important bearing on events that afterward befell, and on my own destiny.