On a Peculiar Noise at Nakitft, on Mount Sinai. 75 



lion of the Arabians, it resembles the tones of El Nakuh, a 

 long board, suspended in a horizontal position in the Greek 

 monasteries, and there used instead of a bell, a mode of calling 

 together the devout now nearly prohibited : hence also pro- 

 bably the tale that a monastery is concealed in the hill. 



Seetzen, although he has not attempted a full explanation 

 of this sound, maintains that it is produced by the grating 

 of the coarse dry sand along the surface of the rock. This 

 very obvious explanation does not appear to have been consi- 

 dered satisfactory, for we find an English traveller, Mr Gray, 

 who visited this place in 1818, of another opinion. He consi- 

 ders the grating of the sand not as the cause, but as an effect, of 

 the sound, and maintains, in common with some other travel- 

 lers, that the sound must, from the existence of hot-springs, viz. 

 those of Hamam Faraulni, in the neighbourhood, be of volcanic 

 origin, although he can give no other reason for this opinion. 



It is certainly not easy, and probably without experiment 

 not possible, to shew how the rolling or sliding of sand down 

 an inclined plane, could produce the remarkable noise heard at 

 Nakuh. Notwithstanding this, the opinion of Seetzen has been 

 confirmed by Professor Ehrenberg, who, in the year 18S3, also 

 visited this remarkable place. He ascended from the base of 

 the hill, over its cover of sand, to the summit, where he ob- 

 served the sand continually renewed by the weathering of the 

 rock ; and convinced himself that the motion of the sand was 

 the cause of the sound. Every step he and his companion 

 took caused a partial sound, occasioned by the sand thus set in 

 motion, and differing only in continuance and intensity from 

 that heard afterwards, when the continued ascent had set loose 

 a greater quantity of sand. Beginning with a soft rustling, it 

 passed gradually into a murmuring, then into a humming noise, 

 and at length into a threatening, of such violence, that it could 

 only be compared with a distant cannonade, had it been more 

 continued and uniform. As the sand gradually settled again, 

 the noise also gradually ceased. From the account of Seetzen, 

 it is also known that this noise is often heard when animals run 

 across the sand ; also when the wind blows violently, or when 

 loose masses of rock set the sand in motion. 



The sand of Nakuii is rather coarse granular, and composed 

 of fragments of transparent quartz. 



