Page:Africa by Élisée Reclus, Volume 3.djvu/85

 FLOEA OF THE CANARIES. §9 The Canaries have a relatively slighter rainfall than Madeira, and especially than the Azores, months at times passing without a single refreshing shower. On an average there are reckoned three hundred rainless days, the regular rains usually beginning at the end of November and lasting two months. They thus mainly coincide with the west winds, although moisture is also precipitated at other times, and especially in spring, when opposing currents of varying temperature meet in this region. Tn winter the clash gives rise to tornadoes, local cyclones destructive to shipping and to the crops. But the great cyclones of the West Indies never sweep the Canarian waters. During the dry or summer season, from April to October, the aerial currents set steadily from north-east to south-west, and the " brisa," or trade wind, is so constant that all navigation of sailing craft in the opposite direction is entirely interrupted. Owing to the friction of opposing atmospheric currents, the moisture is greater on the plateaux and slopes of the mountains. Thus on the Peak of Teyde a layer of clouds intermediate between the trade winds and the counter currents rises and falls according to the elevation of the zone of contact, usually descending in summer down to from 3,600 to 6,500 feet and in winter to between 1,650 and 2,300 feet above sea-level. In Teneriffe three aerial strata — the counter wind, trade wind, and marine breeze — may be observed all superimposed one above the other. In proof of this normal disposition, Humboldt refers to two windmills, which worked nearly always simultaneously, one revolving towards the north-west, the other towards the south. Thus the inhabitants of Teneriffe and of the other mountainous islands are able to remove at pleasure from one climate to another, selecting the degree of heat and moisture best suited to their constitutions. Thanks to this advantage, the number of invalids coming to the Canaries in search of renewed health is yearly on the increase, and these islands will probably in the near future be resorted to more generally even than Madeira. Flora of the Canaries. With a drier climate than Madeira, and especially the Azores, the Canaries present a less verdant appearance than the northern archipelagoes, and in many places are even quite destitute of vegetation. In Lanzarote and Fuerteventura neither forests nor plantations of the same species are any longer visible, and the land here assumes the aspect of the steppe. But patches of woodland still survive in the western group, and especially in Palma, at once the best-timbered and the best-watered of all. But although their vegetation is less exuberant, the Canaries are distinguished from the other archipelagoes by a relatively larger number of different species, Webb and Berthelot's lists comprising as many as a thousand, or more than double the number found in the Azores. At the same time it is impossible to determine which are strictly indigenous, for even before the arrival of the Europeans the Berber natives had already modified the flora by additions from the neighbouring continent. Far greater changes were made by the Spaniards, partly by clearing