The name Tlahualilo, a liquid-flowing aboriginal designation, means "The Devil"! The river gives life to dozens of large cotton-growing _haciendas_, whose owners have become millionaires, as a rule, thanks to this miniature Nile of the Nazas. In this region scientific canal construction has, of late years, been well carried out, but formerly methods were very primitive. On one occasion I was riding with a _hacendado_ friend over his estate, when we crossed the bed of a canal--dry and unused--which wound over the plain. "What is this?" I asked. In reply he informed me that it had been designed to irrigate a large tract of land, but the levels were wrong. In earlier times there were no engineers in the region, and irrigation canals were made by the primitive method of continually pouring water on the ground, or opening a little furrow and letting it run, and then following its course with the construction of the canal! This had been done, but for some reason an error had been made at the starting-point, and the whole work rendered useless. In justice to this primitive method of canal-levelling it must be stated that successful aqueducts were generally made, although naturally their course was often exceedingly tortuous and much longer than would have been indicated by the theodolite and level of the engineer. In the tropical parts of Mexico water is also of great value at times for the irrigation of sugar-cane, as important an industry as cotton, and long lines of canal are constructed for this purpose, but under greater difficulties, due to the broken nature of the ground. Conditions of this nature are found in the State of Morelos, on the Pacific slope, where I stayed for a period, and great tracts of rich soil are irrigated for cane, and are exceedingly profitable. In the future a vigorous and scientific development of irrigation will greatly increase the agricultural wealth of the country in all its sections. Agriculture on a large scale is very profitable, and the owners of _haciendas_ are generally men of wealth and position.