[11] With respect to intercalations, various periods have been taken by ancient nations. And while we take the shortest possible one, of four years; and the Aztecs took fifty two, the Chinese took sixty, and the Persians one hundred and twenty. The _architecture_ of the ancient inhabitants of Mexico and Peru, has been illustrated, within a few years, by several elaborate works; and the subject may be deemed to have been brought, by these works, within the scope of study and comparison. There are two features in this unique order of architecture, which appear to denote great antiquity in the principles developed, namely, the arch and the pyramid. These nations appear to have had the use of squares and parallelograms, in their geometry, without circles, or parabolic lines. The only form of the arch observed, is that called the cyclopean arch, which is made by one course of stones overlapping another, till the two walls meet, and a flat stone covers the space. This is the earliest type of the arch known among mankind, and is believed to be more ancient than the foundation of any city in Europe. The pyramid, as developed in the temple of the sun at Tezcuco, the Mexican teocalli, and the Aonic mounds of North America, compose a form of architecture equally ancient; which can be traced back over the plains of Asia, to the period of the original dispersion of mankind. The temple of Belus, was but a vast pyramid, raised for the worship of Bel. Originating in the Hamitic tribes, in the alluvial vallies and flat-lands of Asia Minor, a perfect infatuation, on the subject, appears to have possessed the early oriental nations, and they carried the idea into the valley of the Nile, and, indeed, wherever they went. It appeared to be the substitute of idolatrous nations, on alluvial lands, for an isolated hill, or promontory. It was at such points that Baal and Bel were worshipped, and hence the severe injunctions of the sacred volume, on the worship established in the oriental world "on high places." Such was the position of the pyramids in the vallies of the Euphrates and the Nile, and the idea appears to have reached America without any deviation whatever in its relative position, or its general design. It was every were, throughout America, as we find it, in the vallies of Mexico and the Mississippi, erected in rich and level vallies, or plains, and dedicated to idolatrous worship.