the water, and could only be reached by boat or drawbridge. The town itself was intersected by numerous canals, and the inhabitants went about as much in boats as on land. Near the coast, pile-dwellings were constructed so that the inhabitants might be out of the reach of wild beasts, and protecting walls of adobes or wooden palisades were also found. Beds in most cases were made of rushes, with cotton sheets, those of the lords being woven with feathers, and for meals a mat was simply spread upon the ground. The primitive hunting-tribes, such as the wilder Chichimec, lived chiefly in caves, though some of the more advanced constructed rude temporary huts. The Tarascans built the walls of their dwellings of natural stones, and constructed the roof of straw thatch, with, apparently, a clay ridge. Thatch was in fact the principal roofing material throughout Mexico, and even the shrines were usually so covered.
One of the chief features of Mexico city was the series of causeways which connected the island with the mainland. The position of these, according to the most recent ideas, can be seen in Fig. i, p. 13. In building them a double palisade was first constructed, and the space between filled with stones and earth faced with rubble. The great dyke which ran from Iztapalapa to Atzacualco, built by the first Montecuzoma on the advice of Nezahualcoyotl, was no less than ten miles long, and was perforated by sluices, by means of which an attempt was made to control the inundations to which Mexico was subject. The effect of this feat of engineering was to cause the portion of lake to the west, called the Lake of Mexico, to become fresh, and to be filled with wild-fowl and fish, for the springs which fed it contained no salt, whereas the streams running into the eastern portion still continued to carry into it the salt which they absorbed on their journey. Another work of economical importance was the double stone
