H. P. Armshy—Digestion Experiments. 355 
Longitudinal Vibrations. 
Before using bar M table IV we compared its note with that 
ofa pitch pipe which had been graduated by a siren. 
The ice gave three-tenths of a semitone of C sharp. 
American Pitch, 
Pitch Pipe ©, 67°93 135°9 Q271°7 543°5 1087 
CH, 71°97 143°9 287°9 575'8 1152 
& = modulus of elasticity, 
” = number of longitudinal vibrations per second, 
4 length of bar, 
density of bar, 
110 C138. A = °920. 
= 
= 
WU 
7. 
40? A = 86 x 10°. 
me 
Summation. 
Average of table I - - - - oni Be MIC’ 
bad “c come a e 2 é = - 65 “ 
= Os Ns wee aes oe ee 
«6 ‘ce ‘a * . nf e - 96 “e 
= *‘ all the observations - - - 72 & 
ne assign greater value to tables III and IV than to I and 
Average of tables III and IV mee CRE Mee 
° “ transverse vibrations ane “ 
ee eo ae. 
“© longitudinal =‘ 
Velocity of Sound in Ice, 
ey S49c10" 
my/t a pete = 290,000 cm. per sec. = 2900 m. per sec. 
about nine times the velocity of sound in air, 
Jefferson Physical Laboratory. 
See 
Arr. XLV.— Contributions from the Agricultural Experiment 
Station of the University of Wisconsin. Digestion Experiments ; 
by H. P. Armssy. 
‘The methods of cattle-feeding worked out by the scientific 
®xperiments of the last twenty years require, as their basis, a 
knowledge of the average composition and digestibility of the 
fodders in common use. Thanks to the labors of American 
*Xperiment stations, we have now a very fair knowledge of the 
Composition of American feeding-stuffs; but for all estimates of 
their digestibility we have been obliged to take’ the results of 
