Precise measurements of the middle room at the second floor level, 8 feet above the base previously stated, are as follows: Eastern side, 24 feet 8½ inches; western side, 24 feet 2 inches; northern side, 9 feet 3½ inches; southern side, 9 feet 1 inch. The eastern room is a little more regular, but there is a difference of 11 inches between the measurements of the northern and southern ends. A similar difference is found in the western room, amounting there to 6 inches. The northern and southern rooms do not afford as good bases for comparison, as a corner is missing in each; but measurements to a point where the interior wall surfaces would intersect if prolonged, show variations of from 6 inches to a foot. The statement that the ruin exhibits exceptional skill in construction on the part of the builders, is not, therefore, supported by facts.

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 in the illustration, a close inspection of the wall itself shows them. It will be noticed that the builders were unable to keep straight courses, and that occasional thin courses were put in to bring the wall up to a general level. This is even more noticeable in other parts of the ruin. It is probable that as the walls rose the exterior surface was smoothed with the hand or with some suitable implement, but it was not carefully finished like the interior, nor was it treated like the latter with a specially prepared material. The material employed for the walls was admirably suited for the purpose, being when dry almost as hard as sandstone and practically indestructible. The manner in which such walls disintegrate under atmospheric influences has already been set forth in detail in this report. An inhabited structure with walls like these would last indefinitely, provided occupancy continued and a few slight repairs, which would accompany occupancy, were made at the conclusion of each rainy season. When abandoned, however, sapping at the ground level would commence, and would in time level all the walls; yet in the two centuries which have elapsed since Padre Kino's visit—and the Casa Grande was then a ruin—there has been but little destruction, the damage done by relic hunters in the last twenty years being in fact much greater than that wrought by the elements in the preceding two centuries. The relic hunters seem to have had a craze for wood, as the lintels of openings and even the stumps of floor joists have been torn out and carried away. The writer has been reliably informed that as late as twenty years ago a portion of the floor or roof in one of the rooms was still in place, but at the present day nothing is left of the floors except marks on the vertical walls, and a few stumps of floor joists, deeply imbedded in the walls, and so high that they can not be seen from the ground.

[PLATE LVI]

INTERIOR WALL OF CASA GRANDE RUIN

The floors of the rooms, which were also the roofs of the rooms below, were of the ordinary pueblo type, employed also today by the American and Mexican population of this region. In the Casa Grande ruin a series of light joists or heavy poles was laid across the shorter axis of the room at the time the walls were erected; these poles were 3 to 6 inches in diameter, not selected or laid with unusual care, as the holes in the side walls which mark the places they occupied are seldom in a straight line, and their shape often indicates that the poles were quite crooked. Better executed examples of the same construction are often found in northern ruins. Over the primary series of joists was placed a layer of light poles, 1½ to 2 inches in diameter, and over these reeds and coarse grass were spread. The prints of the light poles can still be seen on the walls. The floor or roof was then finished with a heavy coating of clay, trodden down solid and smoothed to a level. A number of blocks of this final floor finish, bearing the impress of the grass and reeds, were found in the middle room. There is usually a setback in the wall at the floor level, but this practice was not followed in all the rooms.

The position of the floor is well marked in all cases by holes in the wall, into which beams projected sometimes to a depth of 3 feet, and by a peculiar roughness of the wall. Plate LVI shows two floor levels, both set back slightly and the upper one strongly marked by the roughness mentioned. This roughness apparently marks the thickness of the floor in some cases, yet in others it is much too thick for a floor and must have had some other purpose. The relation of these marks to the beam holes suggests that in some cases there was a low and probably narrow bench around two or more sides of the room; such benches are often found in the present Pueblo villages.

The walls of the northern room are fairly well preserved, except in the northeastern corner, which has fallen. The principal floor beams were of necessity laid north and south, across the shorter axis of the room, while the secondary series of poles, 1½ inches in diameter, have left their impression in the eastern and western walls. There is no setback in the northern wall at the first floor level, though there is a very slight one in the southern wall; none appears in the eastern and western walls. Yet in the second roof level there is a double setback of 9 and 5 inches in the western wall, and the northern wall has a setback of 9 inches, and the top of the wall still shows the position of nearly all the roof timbers. This suggests—and the suggestion is supported by other facts to be mentioned later—that the northern room was added after the completion of the rest of the edifice.

The second roof or third floor level, the present top of the wall, has a decided pitch outward, amounting to nearly 5 inches. Furthermore, the outside of the northern wall of the middle room, above the second roof level of the northern room, is very much eroded. This indicates that the northern room never had a greater height than two stories, but probably the walls were crowned with low parapets. In this connection it may be stated that a calculation of the amount of débris within the building and for a distance of 10 feet about it in every direction, the interior floor level being determined by excavation, showed an amount of material which, added to the walls, would raise them less than 3 feet; in other words, the present height of the walls is very nearly the maximum height.

Subsequent to this examination the ruin was cleared out by contractors for the Government in carrying out a plan for the repair and preservation of the ruin, and it was reported that in one of the rooms a floor level below that previously determined was found, making an underground story or cellar. This would but slightly modify the foregoing conclusion, as the additional débris would raise the walls less than a foot, and in the calculation no account was taken of material removed from the surface of the walls.

In support of the hypothesis that the second roof level of the northern room was the top roof, it may be stated that there is no trace of an opening in the walls above that level, except on the western side. There was a narrow opening in the western corner, but so well filled that it is hardly perceptible. Doubtless it formed a niche or opening in the parapet.