Another myth attributes the earthquake to the restlessness of the serpent Midgard, who encircles the universe, his tail in his mouth. Also, the wolf Fenrir, who is to take part in the final contest that produces Ragnarok, is supposed to have occasional differences of opinion before the time with certain of the fire giants. The earth is then liable to be shaken. Natives of the Tonga group, in the South Pacific, believed that their hero-god, Maui, upheld the world on his breast. When he became restless and shook the earth, they would rush out and beat the ground with sticks to make him lie still. [Illustration: EFFECT OF A POWERFUL EARTHQUAKE ON MASSIVE MASONRY, ITALY.] From traditions concerning Mohammed we learn that the circular earth lies in the midst of a vast sea, and is encircled by an immense whale, upon whose back 700,000 gigantic bulls walk up and down. Said whale swims about the earth very cautiously, but occasionally jostles it slightly. On the night when Mohammed was born this noble animal was so agitated with joy, that had not the Lord restrained him, he would assuredly have overturned the earth. The Sandwich Islanders believed that the goddess Pele, who dwelt in the great volcano of Kilauea, was displeased with the conduct of man; she proceeded to admonish him of her power, by shaking him out of bed in the night, or tumbling his house about his ears. If especially angry, she set her volcanic home to fuming and firing. So-called scientific theories on various topics have in time past been little more respectable, and need not be given any detailed attention. The pious gentry who deemed Roger Bacon a wizard and Columbus and Galileo heretics, would have listened with horror to any effort to explain the phenomena of earthquakes as anything else than a direct manifestation of the wrath of God. Researches in any branch of natural science met with decided discouragement in Christendom during the dark and middle ages; and the goddess of wisdom found a decidedly more congenial atmosphere at Moorish and Saracen courts. Hence the modern science of seismology, as the investigations of earthquakes are called, is comparatively in its infancy. Yet the subject of seismic phenomena has been of interest to the thoughtful from a very early period, earthquakes being of far greater frequency than most persons suppose. Some of the earliest philosophers ventured opinions on the topic; for the records of earthquakes, more distinctly than those of volcanoes, go back to the earliest times.