Fig. 95 illustrates an example of this form.
[Illustration: Fig. 94. Zu?i roof-openings.]
[Illustration: Plate XCIX. Outside steps at Pescado.]
[Illustration: Fig. 95. A Zu?i roof opening, with raised coping.]
In Zu?i, where many minor variations in the forms of roof openings
occur, certain of these variations appear to be related to roof
drainage. These have three sides crowned in the usual manner with coping
stones laid flat, but the fourth side is formed by setting a thin slab
on edge, as illustrated in Fig. 96.
[Illustration: Fig. 96. Zu?i roof-openings, with one elevated end.]
Fig. 94 also embodies two specimens of this form.
The special object of this arrangement is in some cases difficult to
determine; the raised end in all the examples on any one roof always
takes the same direction, and in many cases its position relative to
drainage suggests that it is a provision against flooding by rain on the
slightly sloping roof; but this relation to drainage is by no means
constant. Roof holes on the west side of the village in such positions
as to be directly exposed to the violent sand storms that prevail here
during certain months of the year seem in some cases to have in view
protection against the flying sand. We do not meet with evidence of any
fixed system to guide the disposition of this feature. In many cases
these trap holes are provided with a thin slab of sandstone large enough
to cover the whole opening, and used in times of rain.
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