EEMAEKABLE ECHOES. 223 



echo which is produced by parallel walls is finely 

 illustrated at the Marquis of Simonetta's villa 

 near Milan, which has been described by Addison 

 and Keysler, and which we believe is that 

 described by Mr. Southwell in the Philosophical 

 Transactions for 1746. Perpendicular to the 

 main body of this villa there extend two parallel 

 wings about fifty-eight paces distant from each 

 other, and the surfaces of which are unbroken 

 either with doors or windows. The sound of the 

 human voice, or rather a word quickly pro- 

 nounced, is repeated above forty times, and the 

 report of a pistol from fifty-six to sixty times. 

 The repetitions, however, follow in such rapid 

 succession that it is difficult to reckon them, 

 unless early in the morning before the equal 

 temperature of the atmosphere is disturbed, or 

 in a calm, still evening. The echoes appear to 

 be best heard from a window in the main build- 

 ing between the two projecting walls, from which 

 the pistol also is fired. Dr. Plot mentions an 

 echo in Woodstock Park which repeats seventeen 

 syllables by day and twenty by night. An echo 

 on the north side of Shipley church, in Sussex, 

 repeats twenty-one syllables. Sir John Herschei 

 mentions an echo in the Manfroni palace at 

 Venice, where a person standing in the centre of 

 a square room about twenty-five feet high, with 

 a concave roof, hears the stamp of his foot re- 

 peated a great many times ; but as his position 

 deviates from the centre, the echoes become 

 feebler, and at a short distance entirely cease. 

 The same phenomenon, he remarks, occurs in 

 the large room of the library of the museum at 

 Naples. M. Genefay has described, as existing 



