_f f g g_, which forms the southern and largest portion of the
house (_B_), contains, therefore, twenty-two transverse rows of six
chambers each, or one hundred and thirty-two apartments on the
ground-plan; and it forms a rectangle running from north to south and
east to west respectively of 80.30 m. x 15.11 m.--260 ft. x 50 ft.

The general dimensions of this building (_B_), therefore appear as
follows:--

Length from north to south, east side 133.81 m.--440 ft.
" " west side 134.92 m.--442 ft.
Width of northern appendix 19.07 m.-- 63 ft.
Width along line _a b c_ 19.07 m.-- 63 ft.
" " _d d d_ 15.89 m.-- 52 ft.
" " _e e_ 16.33 m.-- 53 ft.
" " _f f_ 15.24 m.-- 50 ft.
Width of line _g g_, approximated 15.70 m.-- 51 ft.

From the appearance of the ground-plan, as I have been compelled to give
it, it would result that the "first floor" contained two hundred and
eleven cells, or rooms. Such is, however, not the case. The builders of
this extensive fabric had not the means of preparing the hard rock
foundation by removing it wherever it protruded over an average level.
While giving a uniform height to their structure, they accommodated its
ground-plan to the sinuosities of the rock. Out of this accommodation
the irregularities noticed in the construction have mainly arisen. Pl.
II., Figs. 1, 2, 3, will illustrate this statement.

Pl. II., Fig. 1.--Cross-section of _B_ along the line a b c, north end;
_a b_, actually visible top-line; _c d e f g h_, rock; _i k_, top of
probable highest story, now destroyed.

I have every reason to assume that this cross-section holds good for the
entire division (_a b c d d_). From _d d_ on to _f f_ the distance
between the rim of the _mesilla_ to the east and the house is greatest;
the top-rock bends also to the west about _e e_, and there the
irregularities noticed on the diagram about the chambers (_II_ and
_III_) come in. They evidently result from an effort to conform the
general plan to both the lateral and vertical deviations of its base.
About the line _f f_, while the same number of chambers (six) remains in
every transverse row, there is but one story below the general surface
to the east. I may safely assume that south of the line _f f_ all the
rooms of the first floor were on