igoS.] KENNELLY AND UPSON— HUMMING TELEPHONE. 365 



Also the range of frequency is moved bodily towards higher notes. 



All of the experimental series of observations appear to be ac- 

 counted for and explained by the above theory to a first approxima- 

 tion; although in matters of quantitative detail there remains much 

 room for further development. 



In conclusion, the authors desire to express their indebtedness 

 to the Western Electric Co. for the loan of apparatus used in the 

 tests. 



PROC. AMER. PHIL. SOC, XLVH. I89 X, PRINTED OCTOBER 3, IC 



