more prolonged. It seemed as if issuing from under his knees, beneath which the sand, disturbed by his efforts, was sliding downwards along the surface of the rock. Concluding that the sliding sand was the cause of the sounds, not an effect of the vibrations which they occasioned, he climbed to the top of one of the declivities, and, sliding downwards, exerted himself with hands and feet to set the sand in motion. The effect produced far exceeded his expectations; the incoherent sand rolled under and around in a vast sheet; and so loud was the noise produced, that "the earth seemed to tremble beneath him to such a degree, that he states he should certainly have been afraid if he had been ignorant of the cause." At the time Sir David Brewster wrote (1832), the only other European who had visited _Jabel Nakous_ was Mr. Gray, of University College, Oxford. This gentleman describes the noises he heard, but which he was unable to trace to their producing cause, as "beginning with a low continuous murmuring sound, which seemed to rise beneath his feet," but "which gradually changed into pulsations as it became louder, so as to resemble the striking of a clock, and became so strong at the end of five minutes _as to detach the sand_." The Mountain of the Bell has been since carefully explored by Lieutenant J. Welsted, of the Indian navy; and the reader may see it exhibited in a fine lithograph, in his travels, as a vast irregularly conical mass of broken stone, somewhat resembling one of our Highland cairns, though, of course, on a scale immensely more huge, with a steep, angular slope of sand resting in a hollow in one of its sides, and rising to nearly its apex. "It forms," says Lieutenant Welsted, "one of a ridge of low, calcareous hills, at a distance of three and a half miles from the beach, to which a sandy plain, extending with a gentle rise to their base, connects them. Its height, about four hundred feet, as well as the material of which it is composed,--a light-colored friable sandstone,--is about the same as the rest of the chain; but an inclined plane of almost impalpable sand rises at an angle of forty degrees with the horizon, and is bounded by a semi-circle of rocks, presenting broken, abrupt, and pinnacled forms, and extending to the base of this remarkable hill. Although their shape and arrangement in some respects may be said to resemble a whispering gallery, yet I determined by experiment that their irregular surface renders them but ill adapted for the production of an echo. Seated at a rock at the base of the sloping eminence, I directed one of the Bedouins to ascend; and it was not until he had reached some distance that I perceived the sand in motion, rolling down the hill to the depth of a foot. It did not, however, descend in one continued stream; but, as the Arab scrambled up, it spread out laterally and upwards, until a considerable portion of the surface was in motion. At their commencement the sounds might be