that the oldest form of building known to them was therefore an
inclosure of lava-stones, whence the application of the contraction
_hé sho ta_, and its restriction to mean a walled inclosure.

[Illustration: FIG. 492.--Plan of Pueblo structure of lava.]

[Illustration: FIG. 493.--Section of Pueblo structure of lava.]


RECTANGULAR FORMS DEVELOPED FROM CIRCULAR.

It may be well in this connection to cite a theory entertained by Mr.
Victor Mindeleff, of the Bureau of Ethnology, whose wide experience
among the southwestern ruins entitles his judgment to high
consideration. In his opinion the rectangular form of architecture,
which succeeds the type under discussion, must have been evolved from
the circular form by the bringing together, within a limited area, of
many houses. This would result in causing the wall of one circular
structure to encroach upon that of another, suggesting the partition
instead of the double wall. This partition would naturally be built
straight as a twofold measure of economy. Supposing three such houses
to be contiguous to a central one, each separated from the latter by a
straight wall, it may be seen that (as in the accompanying plan) the
three sides of a square are already formed, suggesting the
parallelogramic as a convenient style of sequent architecture.

[Illustration: FIG. 494.--Evolution of rectangular forms in primitive
architecture.]

All this, I need scarcely add, agrees not only with my own