_Detailed Description._

The Casa Grande ruin is often referred to as an adobe structure. Adobe
construction, if we limit the word to its proper meaning, consists of
the use of molded brick, dried in the sun but not baked. Adobe, as thus
defined, is very largely used throughout the southwest, more than nine
out of ten houses erected by the Mexican population and many of those
erected by the Pueblo Indians being so constructed; but, in the
experience of the writer, it is never found in the older ruins, although
seen to a limited extent in ruins known to belong to a period subsequent
to the Spanish conquest. Its discovery, therefore, in the Casa Grande
would be important; but no trace of it can be found. The walls are
composed of huge blocks of earth, 3 to 5 feet long, 2 feet high, and 3
to 4 feet thick. These blocks were not molded and placed in situ, but
were manufactured in place. The method adopted was probably the erection
of a framework of canes or light poles, woven with reeds or grass,
forming two parallel surfaces or planes, some 3 or 4 feet apart and
about 5 feet long. Into this open box or trough was rammed clayey earth
obtained from the immediate vicinity and mixed with water to a heavy
paste. When the mass was sufficiently dry, the framework was moved along
the wall and the operation repeated. This is the typical pisé or
rammed-earth construction, and in the hands of skilled workmen it
suffices for the construction of quite elaborate buildings. As here
used, however, the appliances were rude and the workmen unskilled. An
inspection of the illustrations herewith, especially of plate LV,
showing the western wall of the ruin, will indicate clearly how this
work was done. The horizontal lines, marking what may be called courses,
are very well defined, and, while the vertical joints are not apparent