For ages they had been testing the amount of magnetism in the air at various heights and temperatures and various times of day, month, and year, and recording the results of their investigations. They were now able to decide from these and from their experiences of the pirakno that irregular changes in the weather were due chiefly to magnetic influence. They saw that the tremendous storms which every few years swept the earth had their origin in exceptional inflows of cosmic magnetism. During the history of man since he had come to self-consciousness and to the habit of recording his own movements, there had been many sudden and temporary climatic changes, that had led to vast displacements of the inhabitants of the earth. A series of severe winters in the north and in the temperate zone would strip the trees and fields of all frugiferous qualities, and drive the animals of the chase away to the south in search of food. And the races of man had to follow them. So in the tropics a series of droughts would destroy half the chances of life, and exterminate one-third of the dwellers inland. As a rule the agony there led to no displacement of nations, so passive and fatalistic are they by nature near the equator; but in times when some new religious idea had broken the spell of fatalism, the first goad of starvation drove hordes to search for food in other zones. Oftentimes there has been a simultaneity in the meteorological severity, partly due to a universal influx of interstellar magnetism, but still more to the fact that the earth and the planetary system to which it belongs have swung into a region of space that is exceptionally barren of all life-impetus. At such periods came those wide-spread migrations of the dwellers on the globe that made new eras in history. It was one of those cosmic disturbances of climate that sent the Arabs out of their deserts, a flaming portent along the shores of the Mediterranean with their newly reformed religion, the creed of Mahomet, and at the same moment flung the Saxons against the northern frontier of Charlemagne’s empire, and the Danes on the coast of Britain. So, earlier, in the fourth and fifth centuries of the Christian era, the Huns burst from the east like a torrent, and again and again swept all before them in the west, whilst simultaneously the Goths broke in from the north across the boundaries of the Roman empire. Later, in the ninth century, the Danes and Normans broke away from the north again and again, and plagued Europe with their piratical energy in the very period when the Magyars were migrating from the east to the west. And it was only the closer packing of the continents, and the consequent military organisation of European nations that checked these displacements in later centuries, though there were refluxes towards the east, as in the crusades. But the cosmic meteorology of the earth took different effect in the same