Prof. A. M. Mayer's Researches in Acoustics. 

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fork are sent intermittently into a resonator by means of a revol- 

 ving perforated disk. I will now describe the character of the 

 successive sensations experienced when, starting from rest, we 

 gradually increase the velocity of rotation of the disk until the 

 separate beats of the fork blend into a smooth continuous sensa- 

 tion. When the disk is stationary, with one of its openings op- 

 posite the mouth of the resonator, it is evident that the ear will 



