These plans were primarily intended to be used in the construction of large scale models, and consequently recorded an amount of information that could not be reproduced upon the published drawings without causing great confusion. The methods followed in surveying the ruins underwent some changes from time to time as the work progressed. In the earlier work the lines of the walls, so far as they could be determined, were run with a compass and tapeline and gone over with a level. Later it was found more convenient to select a number of stations and connect them by cross-sights and measurements. These points were then platted, and the walls and lines of débris were carefully drawn in over the framework of lines thus obtained, additional measurements being taken when necessary. The heights of standing walls were measured from both sides, and openings were located on the plan and described in a notebook, as was done in the survey of the inhabited villages. The entire site was then leveled, and from the data obtained contour lines were drawn with a 5-foot interval. Irregularities in the directions of walls were noted. In the later plans of ruins a scale of symbols, seven in number, were employed to indicate the amount and distribution of the débris. The plans, as published, indicate the relative amounts of débris as seen upon the ground. Probable lines of wall are shown on the plan by dotted lines drawn through the dots which indicate débris. With this exception, the plans show the ruins as they actually are. Standing walls, as a rule, are drawn in solid black; their heights appear on the field sheets, but could not be shown upon the published plans without confusing the drawing. The contour lines represent an interval of 5 feet; the few cases in which the secondary or negative contours are used will not produce confusion, as their altitude is always given in figures. PLANS AND DESCRIPTIONS OF RUINS.