A. G. Beli—Production of Sound by Radiant Energy. 467 
sulted from smoking the mica. In this experiment the effect 
was observed by placing the mica diaphragm against the ear and 
also by listening through a hearing-tube, one end of which was 
closed by the diaphragm. The sound was found to be more 
audible through the free air when the ear was placed as near 
to the lamp-black surface as it could be brought without 
shading it. Thus the vibrations produced in lamp-black under 
the above circumstances do not appear to be communicated to 
any very appreciable extent to the diaphragm on which the 
lamp-black is deposited. 
keeping the light steadily directed on the receiver. Wo 
and sentences spoken into the transmitter in a low tone of 
