Some temples are built of only one kind of stone; but more frequently materials of different kinds are put together in unequal proportions. Thus the main part of the temples of Abydos consists of very fine limestone; but in the temple of Seti I., the columns, architraves, jambs, and lintels,-- all parts, in short, where it might be feared that the limestone would not offer sufficient resistance,--the architect has had recourse to sandstone; while in that of Rameses II., sandstone, granite, and alabaster were used. At Karnak, Luxor, Tanis, and Memphis, similar combinations may be seen. At the Ramesseum, and in some of the Nubian temples, the columns stand on massive supports of crude brick. The stones were dressed more or less carefully, according to the positions they were to occupy. When the walls were of medium thickness, as in most partition walls, they are well wrought on all sides. When the wall was thick, the core blocks were roughed out as nearly cubic as might be, and piled together without much care, the hollows being filled up with smaller flakes, pebbles, or mortar. Casing stones were carefully wrought on the faces, and the joints dressed for two-thirds or three-quarters of the length, the rest being merely picked with a point (Note 6). The largest blocks were reserved for the lower parts of the building; and this precaution was the more necessary because the architects of Pharaonic times sank the foundations of their temples no deeper than those of their houses. At Karnak, they are not carried lower than from 7 to 10 feet; at Luxor, on the side anciently washed by the river, three courses of masonry, each measuring about 2-1/2 feet in depth, form a great platform on which the walls rest; while at the Ramesseum, the brickwork bed on which the colonnade stands does not seem to be more than 10 feet deep. These are but slight depths for the foundations of such great buildings, but the experience of ages proves that they are sufficient. The hard and compact humus of which the soil of the Nile valley is composed, contracts every year after the subsidence of the inundation, and thus becomes almost incompressible. As the building progressed, the weight of the superincumbent masonry gradually became greater, till the maximum of pressure was attained, and a solid basis secured. Wherever I have bared the foundations of the walls, I can testify that they have not shifted. [Illustration: Fig. 52.--Masonry in temple of Seti I. at Abydos.]