supervision of Friar Francisco Tembleque, a Franciscan monk, and served for about two centuries to carry water from the mountain Lacayete to the city of Otumba, state of Hidalgo, district of Apan, a distance of 27.8 miles. The aqueduct, which is known as the Zempoala, included three arched bridges of a maximum height of 124 feet. This aqueduct is further interesting from the fact that the original agreement, under which the work was performed, is still in existence, a copy of which was published in the _Engineering News_, 1888, from which the following copy is taken. The first bridge contains forty-six arches, the second thirteen arches and the third sixty-eight arches. The length of the longest bridge is 3,000 feet and the span of the arches at the springing line is fifty-six feet. About five years were required to build the principal part of the aqueduct which is carried on arches. CONTRACT UNDER WHICH AQUEDUCT WAS BUILT I, Friar Cristobal y Chanriguis, preacher and secretary of this holy province of the holy evangel, certify that Father Luis Gerro, preacher and guardian of the Convent of All Saints, Zempoala, has presented to me a patent in favor of natives of said town, whose legal tenor is as follows: We, Friar Juan De Bustamanti, Commissioner General of the Indes of the Ocean Seas, and Friar Juan De San Francisco, Provincial Master of the province of said holy evangel, and Friar Deigo Nolivarte, and Friar Juan De Gavna, and Friar Antonio Centad Rodriquez, and Friar Bernardino De Sahagun, subordinate of priests of said province of the holy evangel, declare: