I have not yet procured what I expect to procure soon,--sand enough from the musical bay at Laig to enable me to make its sonorous qualities the subject of experiment at home. It seems doubtful whether a small quantity set in motion on an artificial slope will serve to evolve the phenomena which have rendered the Mountain of the Bell so famous. Lieutenant Welsted informs us, that when his Bedouin first set the sand in motion, there was scarce any perceptible sound heard;--it was rolling downwards for many yards around him to the depth of a foot, ere the music arose; and it is questionable whether the effect could be elicited with some fifty or sixty pounds weight of the sand of Eigg, on a slope of but at most a few feet, which it took many hundred weight of sand of _Jabel Nakous_, and a slope of many yards, to produce. But in the stillness of a close room, it is just possible that it may. I have, however, little doubt, that from small quantities the sound evoked by the foot on the shore may be reproduced: enough will lie within the reach of experiment to demonstrate the strange difference which exists between this sonorous sand of the Oolite, and the common unsonorous sand of our sea-beaches; and it is certainly worth while examining into the nature and producing causes of a phenomenon so curious in itself, and which has been characterized by one of the most distinguished of living philosophers as "the most celebrated of all the acoustic wonders which the natural world presents to us." In the forthcoming number of the "North British Review,"--which appears on Monday first,[1]--the reader will find the sonorous sand of Eigg referred to, in an article the authorship of which will scarcely be mistaken. "We have here," says the writer, after first describing the sounds of _Jabel Nakous_, and then referring to those of Eigg, "the phenomenon in its simple state, disembarrassed from reflecting rocks, from a hard bed beneath, and from cracks and cavities that might be supposed to admit the sand; and indicating as its cause, either the accumulated vibration of the air when struck by the driven sand, or the accumulated sounds occasioned by the mutual impact of the particles of sand against each other. If a musket-ball passing through the air emits a whistling note, each individual particle of sand must do the same, however faint be the note which it yields; and the accumulation of these infinitesimal vibrations must constitute an audible sound, varying with the number and velocity of moving particles. In like manner, if two plates of silex or quartz, which are but large crystals of sand, give out a musical sound when mutually struck, the impact or collision of two minute crystals or particles of sand must do the same, in however inferior a degree; and the union of all these sounds, though singly imperceptible, may constitute the musical notes of the Bell Mountain, or the lesser sounds of the trodden sea-beach at Eigg."