A. M. Mayer—Researches in Acoustics. 363 
issuing from their mouths is obtained, and the only sound 
that reaches the ear is the faint sound given by the fork’s ac- 
tion on the air outside the angle included by the mouths 
of the resonators. If, in these circumstances, we close the 
balance of the tissue-paper against the hot gases and vapor re- 
mained unimpaired. Thus it appears that the reflecting power 
tracing- per. 
I have also found that the passage of a sheet of cold coal-gas 
across the mouth of the resonator, was sufficient to destroy the 
balance of the interference, and caused a faint sound to issue 
from the other resonator; a similar effect, and nearly equal in 
intensity, was obtained with a sheet of cold carbonic acid gas; 
