228 THE BASIN OF EASTERN PERSIA AND SISTAN.
water, the evaporation of which cools the air that whistles through and renders the interior comfortable. When the wind dies down for a day or two, as happens occasionally, the houses become insufferably hot and myriads of flies and mosquitoes
at once swarm everywhere.
The strength and uniform direction of the wind allow windmills to be constructed with simplicity and ease. The wheel is shaped like an old-fashioned water-wheel, 6 or 8 feet long, and is set vertically on the roof of the mill, directly over the stone which
Fig. 149.—Windmills at Tabas.
it is to turn (fig. 149). About the wheel is built a high mud wall, which is left open on the south side and on the western half of the north side (fig. 150). The wind enters
through the slit at the north, turns the wheel, and finds an exit to the south. Often ten or twelve mills are set in a row, east and west, and at Neh, northwest of Sistan, I saw fifty. One unfortunate effect of the wind is that in Sistan no fruit can be raised upon trees, and in
1 certain places even melons can not thrive. The wild watermelon,
Fig. 150 Hon._ which matures its beautiful but intensely acrid little green and yellow zontal section of a fruits in the dry " nullah" beds, has learned to withstand the wind. Persian windmill. Normally, the vine spreads in all directions, but under the influence
of the wind the branches are bent to the south, and lie in a long bunch so exactly oriented that the plants might almost serve as a compass. Three that I measured were directed S. 3° R., S. 17° E., and S. I I° E.