dense veil in front of the windows in walls and ceiling so that a continuous twilight would prevail. In this uniform climate, plant life developed enormously faster than animal life. The dense clouds could store considerable quantities of heat in the equatorial belt through evaporation in their upper layers and the violent wind storms above the clouds would carry the aqueous vapours to colder regions where the heat would be liberated through new cloud formations. Currents in the oceans now largely attend to this heat transportation and give for instance to the coast of Norway, and indeed to the whole of Western Europe, its remarkably mild, and to life and civilization, propitious climate, but in the carboniferous age humid air currents fulfilled the same task. They moved considerably faster and more evenly than the ocean currents, were not checked or deflected by coasts or islands, and could therefore produce the extraordinarily uniform temperature and the marine climate all over the globe. Such a heat distribution takes place also in our days at a height of about 10,000 m. (6.2 miles) in the so-called “stratosphere,” but the temperature here is very low, about -60° C. (-76° F.), so that the vapour suspended is hardly worth mentioning, and cannot give rise to cloud formations. The quantities of heat carried in these higher strata of the atmosphere are too insignificant to influence the masses of air below, whose temperature, therefore, is almost entirely governed by that of the sun-heated surface of the earth, except where the ocean currents equalize matters, as for instance in the almost wholly water-covered latitudes south of the 30th parallel on the Southern Hemisphere. Even during the carboniferous period at its height, there existed, of course, a temperature difference between pole and equator, but it was very small, some 10° C. (18° F.) perhaps. Undoubtedly, the formation of coal beds was mainly confined to those regions where the climate was most uniform all the year around. The opposite extremity, the dry desert climate, is far more pronounced in the present time. This condition is well known in all continents except Europe, where we hardly can claim a desert but instead have steppes, with a vegetation abundant after the spring rains but fast disappearing with the arrival of the burning summer heat. A particular type of plant life has adapted itself to this periodic change from rain to drought, from bitter cold during the winter to parching sun during the summer. Perennial plants, and particularly trees, can rarely endure the rigors of such climatic upheavals. Animal life on the other hand has proved fairly adaptable and displays considerable wealth.