THE DISSIPATION OF ENERGY AND OTHER 



EFFECTS OBSERVED IN TORSIONAL 



OSCILLATION 



IN the determination of the law of decrease of torsional oscil- 

 lations of an iron wire, when the range of oscillation is large 

 in comparison with the palpable limits of elasticity, an equa- 

 tion of the form 



has been shown by Dr. Peddie (Phil. Mag., July 1894) to 

 give close representation of results where 

 i/=the range of oscillation, 

 #=the number of oscillations since the commencement 



of observations, 

 n, a, b= quantities, constant for any one experiment, depend- 



ing on the initial conditions of the experiment and 



the previous treatment of the wire. 



The present work has been undertaken to find if this 

 equation can with equal accuracy be applied in the case of 

 wires of brass and other materials, and to find the effect pro- 

 duced on the constants of this equation by altering the initial 

 conditions of the wire by change of temperature and by 

 fatigue induced in the wire by repeated extensional or 

 torsional strains. 



METHOD OF CALCULATING THE CONSTANTS 



The method described by Dr. Paddle in a second paper on 

 the same subject (Trans. Roy. Soc. Edin., 1896) was employed 

 for the determination of the quantities n, a, and b. 



Since n log ?/+log (x+a)=log b, 



