A. M. Mayer — Researches in Acoustics. 



91 



peratures were maintained during 15 minutes. We then took 

 the frequency of vibration of the bar. 



The numbers of vibrations of the forks used in the deter- 

 minations of the pitches of the bars were corrected for tem- 

 perature by the coefficient -000 LI 18, determined by Dr. 

 Kcenig in 1880 (Quelques Experiences d'Acoustique, Paris, 

 1882, p. 172, et seq). 



The subsequent tables show the results of the experiments 

 and give the computations of velocities and moduli founded on 

 them. The curves express graphically the effect of change of 

 temperature on the modulus of elasticity of all the bars 

 experimented on. The circles, on or near the curves, give the 

 data as determined by the experiments. 



In Table III, T = temperature of bars, I— the length, £=the 

 thickness, and V=the velocity of sound through the bars, in 

 centimeters. M=the modulus in grams per square centi- 

 meter section of the bar. g, at Paris, equals 980*96. D = the 

 density, and N=the number of vibrations of bar per second 

 at temperature, T. 



All of the bars were annealed, except those of Jonas and 

 Colver steel, of the French aluminum and of brass ; these 

 were experimented on just as they came from the draw- 

 bench. 



For the analyses of the substances of the bars experimented 

 on, I am indebted to my colleagues, Professors Stillman and 

 Leeds. 



Table I. 



Bar. 



I 



t 



V at 20°:= 



N computed by 

 N=V 1-0279^ 



N observed 

 at 20°. 



Biff. 





Steel No. 1 .. 



20-022 



•5025 



150-02x3427-4 v. s. 



662-49 v. d. 



660-8 



+ 1-69 = 





" No. 2 __ 



200246 



•5037 



=5l4178 cms 



663-91 " 



661-0 



+ 291 = 



i 



" No. 3 _. 



20-0225 



•5022 





66207 " 



660-3 



+ 1-77=+^ 



Aluminum. 

















No. 1 



20-0253 



•4993 



150-05x3377 v. s. 



648-51 " 



646-6 



+ 1-91=-. 



i 



No. 2 



200296 



•4991 



= 506719 cm3 



647-97 " 



647-0 



+ 0-97 = 





No. 3 



20-0233 



•4998 





649-80 " 



648-0 



+ 1-8 = 



3^17 



Brass. 















No. 1 



20-02 



•50116 



150-05 x 23864 v. s. 



460-23 " 



459-0 



+ 1-23 = 



3T3 



No. 2 



20-02 



•50147 



= 358079 cms 



460-53 " 



458-95 



+ 1-58 = 



No. 3 



2002 



•50108 





460-16 " 



458-35 



+ 1-81 = 



St. Gobain 



23-516 



•747 



152-2x3582 v. s. 



747-03 " 



749-75 



-2-72 = 



27¥ 



Glass 







=538016 cms 









White Pine. 



41-15 



•803 



171-18 x 3072-75 v.s. 



256-38 " 



256-0 



+ 0-38 = 





Density =-365 







= 525993 cms 











Mean departure of computed from observed value 



of observed value. 



