The Misses French and Cable, well-known missionaries in inland China, have also recorded their observations of the phenomenon in Chinese Turkestan. The City of Sands (Tunhwang) takes its name from the ranges of sand dunes that lie to the south, stretching out into the great desert of Lob. These sand hills possess the property of “singing” when the sand is moved. Before the desert gale blows, a sound like the rattle of drums is heard, but at any time the hills can be induced to voice their curious song by those who will pay the price of climbing their steep slopes. Visitors do this and then slide down the sharp incline from the knifelike edge of the highest point for the sheer fun of hearing the great vibration, which seems to spring from the very center of the mighty hill of loose sand.
Tschiffely, the “Iron Swiss,” hero of the famous horseback ride from Buenos Aires to Washington, records a strange experience he had on the Peruvian coast, and one wonders whether this, too, was allied with the phenomenon of singing sands . He fell asleep one night on a sand hill but was awakened several times by a strange noise like the beating of drums or like a motor launch traveling on a river. As he could see nothing, he went to sleep again and only awoke when the sun was hot. Then he noticed that he had been sleeping near a “gentilar,” as the ancient Indian burial grounds are called.
The next day the natives asked him if he had heard the manchang. As this sounded rather like Chinese to Tschiffely, he asked them what it meant. They explained that the sand hill where he had slept was haunted and that every night the dead Indians of the “gentilar” danced to the beating of drums. In fact, they told him so many blood-curdling stories about the hill that he began to consider himself lucky to be alive.
When later he spoke with an educated gentleman, the latter told him that both Baron von Humboldt and Raimondi, who had once investigated the strange phenomenon of that hill, had expressed the opinion that the peculiar sounds so frequently heard during the night were due to underground waters that moved as the temperature changed. Another theory put forward is that sea breezes blowing from a certain direction hit the sandy ripples on the slopes of the hill to produce this strange sound.
It is to the deserts that one must turn to hear the finest exhibitions produced by singing sands, because the immeasurable quantities of sand which characterize them offer ample opportunities for the production of the sounds. But it should be noted that a similar phenomenon has been reported from beach sands. The little island of Eigg, in the Scottish Hebrides, for instance, is a spot unique along Scotland’s western shores, for in the Bay of Laig are found sands that sing. The singing of beach sands is quite different from that of desert dunes. The beach sands are best described as “whistling” or “squeaking.” The honor of the first discovery of similar sands in England appears to go to Mr. C. Carus-Wilson, who found them about 60 years ago at Studland Bay, on the coast of Dorset. They have also been recorded on the coast of North Wales; and in the United States two observers have reported them at 74 places on the Atlantic coast alone.
But the singing of beach sands is quite different from that of desert dunes. The beach sands are best described as “whistling” or “squeaking,” according to R. A. Bagnold, who ably summarizes existing knowledge in the final chapter of his book, The Physics of Blown Sand and Desert Dunes. The squeak or whistle is produced, he explains, by any rapid disturbance of the dry top layer, particularly just above the high water level when the sand has recently dried out after a shower. It is produced when the palm of the hand is swept across it quickly or when the sand is given a light stab with the end of a pencil. When the sand is removed from the beach, it does not long retain its sound-producing quality. Grains of singing beach sand examined were rounded, but not markedly so, and were fairly uniform is size.
In contrast with the whistling of the beach sands, “the great sound which in some places startles the silence of the desert” is quite a different noise, according to R. A. Bagnold. “I have heard it,” he says, “in southwestern Egypt 300 miles from the nearest habitation. On two occasions it happened on a still night, suddenly—a vibrant booming so loud that I had to shout to be heard by my companion. Soon other sources, set going by the disturbance, joined their music to the first, with so close a note that a slow beat was clearly recognized. This weird chorus went on for more than five minutes continuously.... Native tales have woven it into fantasy; sometimes it is the song of sirens who lure travelers to a waterless doom; sometimes it is said to come upwards from bells still tolling underground in a sand engulfed monastery....”