Page:Popular Science Monthly Volume 66.djvu/406

402 limestone rock which everywhere abounds. This is cut into blocks a foot or more in length, eight or ten inches wide and of different thicknesses.

Even the roof is made of thin overlapping slabs of the same rock supported by slats that rest on wooden rafters. The houses, roof

and wall, are whitewashed at frequent intervals, usually twice a year. The rain that falls on the roofs is carefully collected in covered cisterns, for it is the only source of fresh water in the islands, since