96 A. M. Mayer—Researches in Acoustics, 
on ee of the caesar might be owing to differ- 
nces in the intensities of the various sounds, 1 repeated the 
Soe aie but vibrated the iocks which gave the greater ampli- 
tudes of co-vibration with the lowest intensities ; and although 
I observed an approach toward as os of amplitude, yet the 
fibre gave the maximum swings when Ut, was sounded, and I 
was persuaded that this special Sel was tuned to unison with 
Ut, or to some other note within a semitone of it. The differ- 
ences of amplitude given by Ut, and Sol, and Mi, are ~~ 
siderable, and the table also brings out the interesting obse 
tion that the lower (Ut,) and the higher (Ut, hore of 
Ut, cause greater amplitudes of vibration than any intermedi- 
ate notes, As long as a universal method for the determination 
of the relative intensities of sounds of different pitch remains 
undiscovered, so long will the science of “soon remain in its 
present vague qualitative condition ow, not having the 
means of equalizing the intensities ‘of the eat issuing 
from the various resonant boxes, I adopted the plan of sound- 
ing, with a bow, each fork with the greatest intensity I could 
Se I think that it is to be regretted that Kénig did not 
adhere to the form of fork, Nie inclined prongs, as formerly 
while its amplitude o of vibration was a 3 div. when Ur, was 
sounded. Other fibrils responded to other notes, so that I ‘infer 
froni my experiments on about a dozen mosquitos that their 
fibrils are tuned to sounds extending through the middle and 
next ict octave of the piano. 
made some experiments in this on which show the pos- 
sibility of eventually beste. ‘able to express he intensity of an aerial vibration 
directly in fraction of Joule’s Dynamical Unit, by measuring ‘the heat developed 
in a slip of sheet rubber stretched between the prongs of a fork and enclosed in 
bai 
duced i Soe the oS dag engaged in heating the rubber and when the rubber is 
red nA the method I described in the Amer. Jour. Sci. veo Feb., 
1873. Of gute “ ean determine the amount of heat produced per seco nd by 
a known fraction of the apteenrri we have the amount signers by the vibration 
with its entire intensity. Then means par be devised by whic! al vibra- 
repr 
is intensity, expressed in fraction of Tonle? 8 unit, is stamped upon the 
which ever afterward serves as a _— —_— ure for 0 ger the intensities of rr 
vibrations of all simple sounds having e pitch as The same opera- 
tion can be performed on other forks of P different pitch, may 80 a series sp intensi- 
ties of di t f vibration is obtained expre in a nding 
fractions of Joule’s unit. Recent experiments have ett Cul uth OF of 
roxi ynami ivalent of ten 
