numerous and well laid out. They had no doors, but mats were hung in their place, with shells, broken pottery, or some such thing hung to them to warn the family, by their jingling, of the entrance of any one. It was not customary, however, for any one not a member of the family to enter another's house, and the laws against thieves were so strict that there was little danger from stealing. Conspicuous examples of their skill in architecture will be pointed out when we return to the city of Mexico in the ranks of the conquerors. Let us speak of two great achievements of this people, then we will take up the thread of historical events again.
Their calendar system was so nearly perfect as to excite the highest admiration. It has already been alluded to. Their great "calendar stone," by aid of which they calculated the recurrence of their cycles and the return of, their festivals, may yet be seen in the city of Mexico, where it is cemented into the western wall of the great cathedral; which position it has occupied since 1790, though its antiquity is much greater than that. It is said to weigh forty-five tons, is eleven feet in diameter, and was hewn from a great basaltic rock.
The most wonderful accomplishment of the Mexicans is yet to be mentioned—their celebrated picture-writing. It is thought that this art of representing historical events by means of paintings was an invention of the Toltecs. It is by means of them that their early history, as given in previous pages, has been preserved. Thousands of them were destroyed by the first Spanish missionaries to Mexico, as "works of the devil," but a sufficient number were hidden from them, and afterwards discovered and preserved, to be of service in constructing the aboriginal history. Besides the picture-paintings, proper, they had also a system of hieroglyphs, they could count up to any required number, and each
