Ek. IT- Ch. II. MEXICAN CONSTRUCTION. 579 seem most modern, the upper parts of the doorways, as well as the roofs of the chambers, are formed by bringing the courses nearer together till they meet in the centre, thus forming a horizontal arch, as it is called, precisely as the Etruscans and all the earlier tribes of Pelasgic race did in Europe at the dawn of civilization, and as is done in India to this day. This form is well shown in the annexed woodcut, representing a chamber in the Casa de las Monjas atUxmal, 13 ft. wide. The upper part of the doorway on the right hand has fallen in, from its wooden lintel having decayed. A still more remarkable instance of this mode of construction is shown in the Woodcut No. 1005, rejiresenting a room in a temple at Chichen Itza in Yucatan. The room is 19 ft. 8 in. by 12 ft. 9 in. ; in the centre of it stand two pillars of stone, supporting beams of sapote- wood, which also forms the lintels of the door, and over these is the stone-vaulting of the usual construction : the whole apparently still perfect and entire, though time-worn, and bearing the marks of as great age as any of the other buildings of the place. When the roof was constructed entirely of wood, it probably jDar- took very much of the same form, the hori- zontal beam being supported by two struts meeting at the centre, and framed up at the sides, which would at once account for the appearances shown in the woodcuts Nos. 1000, 1001. It is also probable that both light and air were introduced above the walls, between the interstices of the wood- ^ooe. Diagram of Mexican coiistructiOD. work ; which is further confirmed by the strange erection on the top of the Casa at Palenque (Woodcut No. 998), where the openings look very like the copy of a ventilator of some sort. It is, of course, impossible to ascribe any very remote antiquity to buildings containing so much wood in their construction, and erected in a climate so fatal to the durability of any class of buildings what- ever. In addition to this, it must be borne in mind that the bas-reliefs are generally in stucco, which, however good, is still a very perishable material, and also that the painting on these and on the walls is still bright and fresh. In such a climate as that of Egypt no argument could be drawn from these circumstances ; but in a country subject to tropical rains and the heat and dryness of a tropical summer the marvel is that they should have lasted four or five centuries, and still more that they should have resisted so long the very destructive powers of vegetation. Taking all these circumstances together, the epoch of their erection does not seem a matter of doubt, and all that remains for the elucidation of their history is that they should be arranged in a sequence during the six or eight centuries which may have intervened between the erection of the oldest and the most modern of these mysterious monuments.
