VALLEY OF THE RIO GRANDE. 189 
inches thick, and baked in the sun. This material, 
with slight repairs, will endure for centuries. Some- 
times chopped straw and gravel are mixed with it, 
which greatly improves its quality. The houses of the 
better classes are large, and built in the form of a hollow 
square. The walls are from two to three feet in thick- 
ness, and have but few openings. When plastered 
and whitewashed they look very neat, and make com- 
fortable -dwellings. All the floors are laid with mud, 
concrete, or brick. Such a thing as a wooden floor is 
unknown in the country. This mode of building, as 
well as the material, is precisely that adopted by the 
Church and Plaza, i us ; ‘ 
ancient Assyrians, and practised at the present day on 
the banks of the Euphrates and the Nile. From the 
