On the day of our visit, Lieutenant Semmes, of the navy, who had provided himself with a pocket sextant and tape-line for the purpose, determined its altitude to be 205 feet. As this measurement differed so widely from that of Humboldt, Lieut. S. requested Lieut. Beauregard, of the engineers, who visited the pyramid a few days afterwards, to test his observations; which Lieut. B., using a longer base, did, making the altitude 203 feet. These two observations, from different points, with different bases, and both with the sextant, show conclusively that Humboldt, who used a barometer, is in error. The mean of the two is 204 feet, which we may henceforth regard as the true height of this extraordinary monument--being nearly half as great as that of the pyramid of Cheops in Egypt. The pyramid of Cholula is quadrangular in form, and truncated--the area of the apex being 165 feet square. On this area formerly stood a heathen temple, now supplanted by the Gothic church of our Lady of Remedios. The temple on this pyramid was, in the days of Cortéz, a sort of Mecca, to which all the surrounding tribes, far and near, made an annual pilgrimage, held a fair, and attended the horrible human sacrifices peculiar to their superstition. Besides this great temple, there were, as we learn from the letters of Cortéz to Charles V., and also from the simple diary of his doughty old Captain, Bernal Diaz, some 400 others in the city, built around the base of the larger. The city itself contained 40,000 householders, and the whole plain was studded with populous villages. The plain is now comparatively a desert, and two or three thousand miserable leperos build their mud huts and practice their thievish propensities upon the site of the holy city. [Illustration: RUINS OF THE PYRAMID OF CHOLULA.] THE TERRITORY OF TLASCALA.