SOUND. 325 



* 



without any windows or doors, by which the sound might 

 be dissipated or lost. The repetition of the sound dwells 

 chiefly on the last syllable, which might have been alter- 

 ed by allowing a greater distance between the two wings ; 

 but possibly it was apprehended, that the number of the 

 repetitions would be diminished by that means. Two or 

 more bodies placed opposite each other, at different 

 distances, are requisite to form a multiplied echo ; or the 

 wall at which the speaker stands, must have another wall 

 opposite to it, so as to form two parallel planes, which 

 will alternately reflect to each other the sound communi- 

 cated to them, with as little dissipation as possible. This 

 last circumstance is found in the two parallel wings of 

 this seat, which, forming right angles with the main body 

 of the building, have a very surprising effect. A man's 

 voice is repeated above forty times, and the report of a 

 pistol above sixty, by this echo : but the repetition is so 

 quick, that it is difficult to tell them, or even to mark 

 them down, unless it be early in the morning, or in a 

 calm still evening ; when the air is rather too moist or 

 too dry, the effect is found not to answer so well.' 



Southwell mentions a building, similar to the palace 

 of Simonetta, which had projecting wings, and produced 

 sixty repetitions of every sound. 



The Abbe Guynet describes an echo on the road from 

 Rochepot to Chalons, which repeats, in the day-time, 

 fourteen syllables well articulated, and, during the night, 

 sixteen syllables. 



About three leagues from Verdun, there is a singular 

 echo, occasioned by two towers projecting from the body 

 of a house, and distant twentysix toises, or about fifty 

 metres. When a person stands in the line between the 

 two towers, and pronounces a word in a pretty high tone, 

 he will hear it repeated twelve or thirteen times at equal 

 intervals, and always more feebly. If he places himself 

 at a certain distance out of this line, the echo is no 

 longer heard. One of these towers has a low apartment 

 vaulted with hewn stone, while the other has its vestibule 

 vaulted. 



In the memoirs of the French Academy of Sciences 

 for 1792, there is described a curious echo, at Geuefay, 



