242 A. M. Mayer—Researches in Acoustics. 
in the study of the analogical phenomena of light. A simple 
sound was obtained by vibrating a fork before the mouth of its 
corresponding resonator, and this sound was broken up into 
flashes, or explosions, by alternately screening and unscreening 
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the mouth of the eaaae b | f d di 
ee , Dy means of a perforated disc, 
which rota between the resonator and the fore ; as is shown 
= me tos oe figure (1). The mean diameter of the 
: open Sectors of the dise equalled the diameter of the mouth of 
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