Among the granite rocks on the Orinoco, Baron Humboldt heard the strangest subterranean sounds; and at the palace of Carnac, some of Napoleon’s _savans_ heard noises exactly resembling the breaking of a string. It is curious that Pausanias applies exactly this expression to the sounds of the Memnonian granite,—the colossal head of Memnon, which was believed to speak at sunrise. He writes,—“It emits sounds every morning at sunrise, which can be compared only to that of the breaking of the string of a lyre.” Juvenal has the same notion, but he has multiplied the sounds. The mystery of Memnon may be readily explained, by the temperature and density of the _external_ air differing from that _within_ the crevices, and the effort of the current to promote an equilibrium; yet these simple sounds were in course of time warped into articulate syllables, and at length obtained the dignity of an oracular voice. And in these illustrations, fair Castaly, you have the clue to all the mysteries of demonia and fairyland. To these natural illusions, let me add the triumphs of phonic mechanism and the peculiar faculty of the ventriloquist, the secrets of which the science of Sir David Brewster has so clearly developed. The wondrous heads of Memnon, and Orpheus, and Æsculapius, the machines of Albertus Magnus, and Sylvester, are now held but as curious specimens of art, and are indeed eclipsed by the speaking toys of Kratzenstein, and Kempelin, and Willis, and Savart, and the ingenious instruments of Wheatstone. Of ventriloquism, it is not my purpose to speak; but there is a wonder of our time in the person of young Richmond, which, with many distinguished physiologists, I examined at the _conversazione_ of Dr. E——, in C—— Street. When Richmond sat himself to _perform_, we heard a subdued murmur in his throat for about half-a-minute, when suddenly a sound issued of the most exquisite and perfect melody, closely resembling, but exceeding in delicacy, the finest musical box. The mouth was widely open, and the performance was one of considerable effort. The sounds were a mystery to us at the time, for they were perfectly unique, and are yet not satisfactorily explained. It is decided, however, by some, that the upper opening of the windpipe may be considered as a Jew’s-harp, or Æolina, of very exquisite power, _behind_ the cavity of the mouth, instead of being placed _between the teeth_. ASTR. And thus concludes our lecture on special mechanics. EV. I professed no more, Astrophel. It may be the privilege of the _sacred poet_ to soar beyond the confines of our own planetary system: “Into the heav’n of heav’ns he has presum’d, An earthly guest, and drawn empyreal air.”