Prof. A. M. Mayer's Researches in Acoustics. 377 



those of the second joint from the base of the antenna to those 

 of the second joint from the tip. These fibrils are highly elastic, 

 and so slender that their lengths are over three hundred times 

 their diameters. They taper slightly, so that the diameter at the 

 base is to the diameter near the tip as 3 to 2. 



I cemented a live male mosquito with shellac to a glass slide, 

 and brought to bear on various fibrils a one-fifth objective. I then 

 sounded successively, near the stage of the microscope, a series 

 of tuning-forks with the openings of their resonant boxes turned 

 towards the fibrils. On my first trials with an Ut 4 fork of 512 

 vibrations per second, I was delighted with the results of the 

 experiments ; for I saw certain of the fibrils enter into vigorous 

 vibration, while others remained comparatively at rest. 



The Table of experiments which I have given is characteristic 

 of all of the many series which I have made. In the first column 

 (A) I have given the notes of the forks in the French notation, 

 which Konig stamps upon his forks. In the second (B) are the 

 amplitudes of the vibrations of the end of the fibril in divisions 

 of the micrometer-scale; and in column C are the values of 

 these divisions in fractions of a millimetre. 



A. 



B. 



Ut 9 . 



. 0-5 div. 



Ut s . 



• 2-5 „ 



Mi 3 . 



• 1-75 „ 



Sol 3 . 



■ 2-0 „ 



Ut 4 . 



• 6-0 „ 



Mi 4 . 



• 15 „ 



So) 4 . 



1-5 „ 



bi- . 



• 1-5 „ 



Ut. . . 



• 2-0 „ 



c. 





•0042 millim 



0200 



a 



•0147 



)) 



•0168 



)> 



0504 



■>> 



0128 



a 



•0126 



t) 



•0126 



}} 



•0168 



a 



The superior effect of the vibrations of the Ut 4 fork on the 

 fibril is marked ; but thinking that the differences in the ob- 

 served amplitudes of the vibrations might be owing to differ- 

 ences in the intensities of the various sounds, I repeated the 

 experiment, but vibrated the forks which gave the greater ampli- 

 tudes of co vibration with the lowest intensities; and although I 

 observed an approach toward equality of amplitude, yet the 

 fibril gave the maximum swings when Ut 4 was sounded ; and I 

 was persuaded that this special fibril was tuned to unison with 

 Ut 4 or to some other note within a semitone of it, The differ- 

 ences of amplitude given by Ut 4 and Sol 3 and Mi 4 are con- 

 siderable ; and the Table also brings out the interesting ob- 

 servation that the lower (Ut 3 ) and the higher (Ut 5 ) harmonics 

 of Ut 4 cause greater amplitudes of vibration than any interme- 

 diate notes. As long as a universal method for the determina- 



