The most important of these desert winds is the sirocco, a wind that is most likely to blow in spring and summer, although occurring in autumn also, and to a very limited degree in the winter season. The sirocco crosses the Mediterranean and is felt in the southern portions of France, on the Italian Riviera, and in other parts of southern Europe. It is especially common on the High Plateau; for example, during five years it was reported on an average of 28.4 days each year. It does not generally last more than three days, but at Batna, in July, 1902, it was recorded on eight consecutive days. The sirocco operates to lower the relative humidity and to raise the temperature. For instance, on the first day of the eight-day sirocco above alluded to, the average relative humidity was 16 per cent, while the average on the preceding day was 25.6 per cent. It has already been remarked that on the days of the greatest temperature variation the sirocco was usually blowing. In the desert the winds often bring with them much dust and sometimes last during several days; for example, one is reported at In Salah, in May, 1904, for six consecutive days. Such winds on the desert may come from the north, or at least may be northerly, and when storms of this character are in progress, although possibly destructive of animal life or at least comfort, the effects as regards decreasing the relative humidity and raising the air temperature are not so marked as is the case when the sirocco is blowing. =SOME CHARACTERISTICS OF THE VEGETATION OF THE TELL.=