Corres^jondence — ZT. J. Loice. 673. 



dismay that it would appear to intrude on the subject of the 

 President's Address, and on hearing the address I found that the 

 President actually discussed the fusion temperature of albite from 

 one extreme, whereas I had hoped to coax a discussion on the other 

 extreme. Thus, instead of being able to ask the opinion of the 

 section, I was obliged with all emphasis to warn the section not 

 to allow my paper to be an excuse for discussing the President's 

 views, and so transgress the inviolable custom of the British Asso- 

 ciation, not to attack a chairman when he is not free to defend 

 himself- My paper being sent in too late for me to supply an 

 abstract, the Recorder of Section C most kindly wrote the excellent 

 epitome you have published, and therein stereotyped an undoubted 

 ambiguity which I subsequently con-ected in reading. Of course, 

 hornblende does not always contain water, as might be inferred 

 from my manuscript ; but certain varieties are said to do so. But 

 in the event of the hornblende being rejected, the chlorite, epidote, 

 zoisite, and the fluid inclusions in the albite, are sufficient to prove 

 my point. A. E. Hunt. 



FOXWOKTHY, MORETONHAMPSTEAD. 



'SONOROUS' SAND. 



Sir, — In September last I paid a visit to Tenby, and while there 

 made a point of seeing the notable junction between the Old Eed 

 and Carboniferous series of rocks. The section is met with a few 

 miles to the west of Tenby, in a small bay called Skrinkle Haven. 

 I was doubly repaid for the effort of getting to this not very 

 accessible spot by seeing a most interesting geological section, and 

 finding musical notes emitted from some of the sand traversed while 

 examining the junction. 



I had never met with the phenomenon before, and, being pre- 

 occupied, at first attributed the sounds to a knocking together of 

 articles on my person ; but, giving my attention to it, found the 

 sounds arose from my feet at each step, as my boots sank into the 

 sand. The notes were clear and metallic, and were emitted only 

 from the dry, loose sand above the range of the tide. I did not test 

 its ' musical ' property in any other way than walking in it, but found 

 an increase in the sound on thrusting the heel deeper into the sand. 



In Nature, vol. xxxix, there are references made to investigations 

 and explanations in regard to these sounds. Dr. Julian and Pro- 

 fessor Bolton attribute them to " a film of condensed air round 

 each grain of sand, which acts as an elastic cushion, and enables 

 the sand to vibrate when disturbed," while Mr. C. Carus Wilson 

 considers the sound to be caused by friction, " the cumulative effect 

 of numerous vibrating particles that becomes audible." 



In accordance with Mr. Wilson's theory, the grains in the patch 

 of sand which emitted the sounds " were rounded, polished, and 

 free from fine fragments ; they must have had sufficient amount of 

 ' play ' to enable them to slide one against the other ; the grains 

 were perfectly clean, and possessed a certain degree of uniformity, 

 within a certain range of size" (vide Nature, vol. xliv, p. 322). 



