Peter sniffed the air, and then gave voice to a long and piteous howl. "We had better be going," said Linton, while Zenobia, still stooping, tried to soothe the dog. When she looked up there was an expression on Linton's face that puzzled her. She rose quickly and laid her hand upon his arm, following his gaze upward and around. "What does it mean?" she asked, breathlessly. "If this were not England," he replied, with hesitation, "I should think it meant...." As he spoke a low but formidable rumble became suddenly audible, coming not from above, but from below. Fraught with indescribable awe and menace, it produced an instantaneously petrifying effect. They stood rigid, holding to each other, waiting, listening for the coming climax. It came as in a flash. The rumble grew into a thunderous roar. A blue flame suddenly shot into the heavy clouds above them, and beneath their feet the solid earth rocked and swayed, again and yet again, as if with the rolling motion of a mighty wave. CHAPTER XXI. THE WRATH OF SUL. The earthquake, in the twinkling of an eye, had changed the face of all nature around them, and while it did so it annihilated stereotyped manners and conventional restraints. To Zenobia it did not seem strange that Linton's arms should be folded protectingly about her, or that she should cling to him, face to face and heart to heart. The moment of the earth's convulsion had bridged a gulf and wrought a revelation. They knew themselves, beyond all doubt, for what they were, lovers and twin souls, pledged to each other by unspoken vows. The dreadful shock had come and gone, but the external changes and terrors which the catastrophe had brought about could not be immediately realised. Presently they discovered that the ground had moved with them, and that they had been swept to a considerable distance from the plateau on which they had been standing. A great gap yawned where the sundial had stood. Peter had disappeared. They themselves had been saved from falling by the trunk of a giant tree--one of the few which had not been up-rooted--while below them, on the slope of the hill, new spaces were revealed where other trees had crashed down to the ground. The air was full of a strange echoing din, caused by the collapse of buildings outside the limits of the park and in the town below. In the midst of these reverberating sounds, and in strange contrast, was heard the prolonged wail of terrified women and the shrill cry of a frightened child. Gasping, and looking up the hill, they could see, rising from Lansdown, dense volumes of sulphurous smoke, through which shot vivid gleams of forking flame. Elsewhere a greyish veil began to spread across the land. A steaming, suffocating atmosphere choked their lungs. "There may be another shock! We must escape for our very lives," Linton whispered hoarsely. Zenobia, white to the lips, made a faint gesture of assent. "Hold my hand! We must find a way across the river," he said quickly.