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POPULAR SCIENCE REVIEW. 
All who have passed much time on sandy shores, or among 
sand-dunes, must have remarked the peculiar whistling sound 
produced by the friction of the particles of sand against each 
other. Similar sounds, but far louder, are produced when dry 
sand runs down a slope. Captain IT. S. Palmer has described 
such sounds as heard at Jebul Nagus, near Mount Sinai. 
Coarse sand, derived from the waste of the sandstone hills, is 
carried by high winds up the slope of the hill ; here it lies at 
the angle of rest (30°), and the slightest cause is sufficient to 
set it in motion. Sometimes the sound is as soft and low as 
the hum of a humming-top ; sometimes it almost approaches 
the roar of thunder. 
