﻿Torsional Oscillations of Wires. 39 



The curves C, G, H, I, J, K are omitted as they were made 

 with an entirely different object and the readings did not 

 cover the same range. 



The actual value of the constant added to x depends upon 

 the interval which elapses after starting the experiment until 

 the first reading is taken. Thus the fact that in B this constant 

 is greater by about unity than the similar constants in D, E, F, 

 while the first reading in B is much less than the first readings 

 in D, E, F, points to the conclusion that the first reading in that 

 curve was taken one oscillation later than the first readings in 

 the latter. We should therefore expect that the value will be 

 small when the initial range is large, as in M. The values of 

 the other two constants in the equation for M are much in- 

 creased relatively to their values in the preceding equations — 

 a fact which illustrates the dependence of the action at any 

 stage upon the previous treatment of the wire. The decay of 

 the oscillations is at first more rapid, afterwards more slow, 

 than in the preceding experiments. 



In P the phenomenon of elastic fatigue is very apparent. 

 The conditions were practically the same in this experiment 

 as in, for example, E, F, and 0, with the exception that in P 

 the wire was kept oscillating to the maximum extent for about 

 half an hour before the observations began. The rate of decay 

 of the oscillations is immensely increased at all the observed 

 values of the range. 



Putting aside the special experiments M and P, we find that, 

 after the wire had once reached a steady state (in B), the steady 

 state was maintained day after day ; so that it was easy to 

 repeat an experiment under practically the same conditions. 

 Even the exceptional treatment in M did not prevent the 

 return of the wire to its old condition before the experiment 

 on the following day was performed. In only one case, L 1? 

 is there any exception, and this may have been due to a 

 difference of temperature. 



In the earlier experiments the initial range is said to be 

 over 100. No exact record was kept, but the excess was con- 

 siderable ; the actual angle was probably about 125. In the 

 experiment the angle was maintained steadily at 125 for some 

 time before the wire was let go and the observations were 

 begun. The constauts were not altered by this treatment ; 

 and this seems to indicate that the " after-action " under 

 steady stress has little or no effect in these experiments, which 

 are made under otherwise similar conditions. 



The experiment C was performed on the same date as B ; 

 so that D was performed after the wire had been at rest for 



