32 DR. F. HORTON ON THE EFFECTS OF CHANGES OF TEMPERATURE 



TABLE VI. Platinum Wire. 



From the above table it will be noticed that, with the exception of the first 

 heating, increase of temperature increases the logarithmic decrement. This result 

 is the opposite to that obtained for soft iron. The logarithmic decrement was 

 continually decreasing with the time, the rate of decrease being more rapid the 

 higher the temperature. This time effect masks the effect of temperature to such 

 an extent that no useful knowledge is obtained by plotting the results given in 

 Table VI. 



When the determinations of the rigidity had been completed, a series of observa- 

 tions was taken to see in what manner the period and logarithmic decrement varied 

 with the amplitude of vibration of the vibrator. A set of observations was taken 

 at temperatures very near to 19 C., and a second set at temperatures very near to 

 9 8 '6 C. The observed periods were corrected to these temperatures. 



The results of these experiments are recorded on Diagram VI., in which the 

 continuous lines show the alteration of the period of vibration, and the dotted lines 

 the alteration in the logarithmic decrement of the oscillations. It will be noticed 

 that both the period and logarithmic decrement increase with the amplitude of 

 vibration, and that the rate of increase of each is less at larger amplitudes than at 

 smaller ones. The curves corresponding to the same temperature are of similar 

 form. 



Gold. 



A pure gold wire was used. As with platinum and iron, the period of vibration 

 diminished with time. The amount of this diminution got less and less on repeated 



