226 LETTERS ON NATURAL MAGIC. 



became acquainted with confessions of the gravest 

 import. This divulgence of scandal continued 

 for a considerale time, till the eager curiosity of 

 one of the dilettanti was punished, by hearing 

 his wife's avowal of her own infidelity. This 

 circumstance gave publicity to the whispering 

 peculiarity of the cathedral, and the confessional 

 was removed to a place of greater secrecy. 



An echo of a very peculiar character has been 

 described by Sir John Herschell in his Treatise 

 on Sound, as produced by the suspension bridge 

 across the Menai strait in Wales. u The sound 

 of a blow with a hammer," says he, " on one of 

 the main piers, is returned in succession from 

 each of the cross-beams which support the road- 

 way, and from the opposite pier at a distance of 

 five hundred and seventy-six feet ; and in addition 

 to this, the sound is many times repeated between 

 the water and the road-way. The effect is a 

 series of sounds which may be thus written : the 



Fig. 51. 



r rrrrrrrr 



first return is sharp and strong from the road-way 

 over-head ; the rattling which succeeds dies away 

 rapidly, but the single repercussion from the 

 opposite pier is very strong, and is succeeded by 

 a faint palpitation, repeating the sound at the 

 rate of twenty-eight times in five seconds, and 

 which, therefore corresponds to a distance of a 

 hundred and eighty-four feet, or very nearly 

 the double interval from the road-way to the 



