AUDITORY APPARATUS OF THE MOSQUITO. 585 
in its present vague qualitative condition.* Now, not having the 
means of equalizing the intensities of the vibrations issuing from 
the various resonant boxes, I adopted the plan of sounding, with 
a bow, each fork with the greatest intensity I could obtain. I 
think that it is to be regretted that Kénig did not adhere to the 
form of fork, with inclined prongs, as formerly made by Marloye ; 
for with such forks one can always reproduce the same initial in- 
tensity of vibration by separating the prongs by means of the 
same cylindrical rod which is drawn between them. Experiments 
similar to those already given revealed a fibril tuned to such per- 
fect unison with Ut, that it vibrated through 18 divisions of the 
micrometer or -15mm., while its amplitude of vibration was only 
3 div. when Ut, was sounded. Other fibrils responded to other 
notes, so that I infer from my experiments on about a dozen mos- 
quitoes that their fibrils are tuned to sounds extending through the 
middle and next higher octave of the piano 
To subject to a severe test the supposition I now entertained, 
that the fibrils were tuned to various periods of vibration, I meas- 
ured with great care the lengths and diameters of two fibrils, one 
of which vibrated strongly to Uts, the other as powerfully to Ut,; 
and from these measures I constructed in homogeneous pine wood 
two gigantic models of the fibrils; the one corresponding to the 
Ut, fibril being about one metre long. After a little practice I 
Sueceeded in counting readily the number of vibrations they gave 
When they were clamped at one end and drawn from a horizontal 
Position. On obtaining the ratio of these numbers I found that 
E I have recently made some experiments in this direction, which show the possi- 
ty of « eventually being able to express the intensity of an aerial vibration directly 
fraction of Joule’s Dynamical Unit, by measuring the heat developed in a slip of 
a 
can be devised b i i fork can always 
y Which the aerial vibration produced by this fo 
Produced with the same intensity. This anas expressed in fraction of Joule’s unit, 
— afterwar: TOOS 
s0 The operation can be performed on on other forks of different pite 
a series of Sru ka of different periods of vibration is obtained expres ma 
< ding series of fractions of Joule’s unit. Recent ents _— given 
lent oft hundred thousandth of a Joule’s unit as the approximate dynamic equiva- 
term tet seconds of aerial vibrations produced by an Uts fork, set in motion by in- 
nlar: 
ced before a 
i 
