May 7, 1920] 



SCIENCE 



463 



There is every probability that Mr. Visoher 

 is mistaken in his guess that the sounds are 

 made by the blowing of the wind through a 

 crevice in the rock, as will be seen by a gen- 

 eral consideration of the subject, before I at- 

 tempt to set forth the prohahle scientific expla- 

 nation of the phenomenon. It is not confined 

 by any means to the Sahara, or for that matter 

 to desert places. 



Near the coast of one of the Hawaiian Is- 

 lands is an old graveyard. The winds blow 

 ceaselessly across its barren expanse and it is 

 fast being buried by coral sands. Passing 

 fisher boats give this shore a wide berth, for 

 when the wind is right, there arises from the 

 white expanse a strange wail, like the howl of 

 a dog, which is attributed to the restless spir- 

 its of the departed. 



, On the coast of Lower California, there is a 

 locality which emits, at times, a bell-like sound. 

 Here too the winds have pUed up fine sand, 

 and the peons declare that under its mounds 

 lie buried the ruins of a convent, the bells of 

 which toll with muffled tones, at the hour of 

 prayer. 



The infrequent traveler in the region of Mt. 

 Sinai, camping at the mouth of the Wady el 

 Der, sometimes hears at sunset, a deep musical, 

 (booming sound, descending from the heights 

 above. It is the great wooden gong of a monas- 

 tery, perched upon the clifp. Such a gong is 

 common in Arabia and is named a " Nagous." 

 On the borders of the Isthmus of Suez stands 

 a hill known as "Jebel Wagons " ; that is, the 

 Mountain of the Gong. The Ara;bs tell of 

 weird sounds heard at this mountain — in 

 storms, loud and wild, audible from a distance ; 

 in more quiet weather, low and musical. Jebel 

 Nagous is alluded to in the " Arabian Nights." 

 The American scientist, the late Dr. H. 

 Carrin^on Bolton, some years before his 

 death, organized an expedition to visit the 

 mountain. After four days' journey from Tor, 

 they went into camp at the base of the hill, 

 jwhich was found to be about 950 feet high. 

 Dr. Bolton heard the music — a. song of several 

 notes, rising and falling, with one continuous 

 deep undertone, like an organ note, and was 

 able to ascertain the cause. Here, as in the 



other places named above, it is due to singing 

 sands. The winds continuously blow this sand 

 up against the sides of the hill, and impelled 

 by the wind, it rusbes up the slopes, emitting a 

 multitude of tiny, tinkling notes, which when 

 combined, make a considerable volume of 

 sound. Then, just as the waves of the sea 

 driven up the beach, rush downwards again, so 

 the sand blown up the steep incline continu- 

 ally slides back, the angle of rest being about 

 thirty-one degrees. It is the returning fiow 

 that gives out the steady undertone, increased 

 by the echo from a sandstone cliff, and vary- 

 ing with the ever-changing wind. 



What are singing sands ? Every one has no- 

 ticed the musical note made by the runners of 

 a sleigh on a cold, clear night, which is caused 

 by the impact of the snow or ice particles upon 

 each other under the pressure of the vehicle. 

 No ear could detect the sound made by two ice 

 crystals, but when this is multiplied a thou- 

 sand-fold, the combined effect is that of an in- 

 strument of music, playing one rather shriU 

 note. Something of the kind is Observed on 

 parts of many sea beaches or other sand de- 

 posits; when they are walked upon, they give 

 forth a note which varies with the locality. 

 Ordinary " singing beaches " or " musical 

 sands " are rather common, and the phenome- 

 non has often been described and scientifically 

 studied. The sounds are usually like the 

 musical note which may be evoked when the 

 wetted finger is rubbed around the edge of a 

 glass bowl. Up to 1908, seventy-four localities 

 had been noted in this country and eighteen 

 a^broad. In spite of this study, the true cause 

 of the phenomenon is not yet certainly under- 

 stood. It does not seem to make any difference 

 whether the sands have been formed from crys- 

 talline or amorphous rooks. They differ widely 

 in different localities in their mineralogical 

 constituents, yet on the same beach, one place 

 will give out a sound when disturbed, while 

 another, a few yards away, is silent though ap- 

 parently identical in structure. The property 

 may be quickly lost or may be retained for 

 months. When the sand is kept in a paper 

 bag, its quality is best preserved; shaking in a 



