IOWA ACADEMY OP SCIENCE 
189 
• It will be seen that for small initial amplitudes the wire is in its be- 
havior not far different from ordinary wires, i. e., its change in period 
with amplitude is small, but it will be seen also that as the initial am- 
plitude increases, the periods corresponding to a given amplitude in- 
crease in a remarkable manner. Not only does the period increase, but 
so also does the internal friction, as is evident when we examine the 
total number of vibrations necessary to bring the wire down to a cer- 
tain small amplitude, say 5 degrees. This number will be noted in 
table 2. In the column headed is the first obtained reading for 
TABLE 2. 
o° 
T 
Vibration 
to 5° 
K ny , .80 
14.1 
3270 
625 
Dpr* 1 
37.3 
2190 
425 
T)PP . 9 
51.0 
1093 
210 
.8 
95.0 
664 
125 
Ppr* . 4 
154.0 
484 
88 
Dpr> . 
369.0 
567 
100 
the maximum amplitude from the rest point. In column headed 
is the number of seconds which elapsed while the pendulum fell from 
0° to 5b In the last column headed ''Vibrations to 5°” are in each case 
the number of vibrations that occurred while the torsion pendulum 
was coming down from the given initial amplitude to an amplitude of 5 
degrees. It is quite evident then that as the initial amplitude is gradu- 
ally increased the wfire seems gradually to change its elastic condition. 
The remarkable fact, however, is that the elasticity of this wire when 
determined by a static method has been found to be practically con- 
stant. There is not space in this paper to describe the experiments on 
the statical determination of the elasticity of the wire. 
A better insight into the frictional losses in the wire, following these 
different experiments is obtained from an examination of the varia- 
tions in the logarithmic decrement with the amplitude. These decre- 
ments have been calculated for the above set of experiments, and al- 
though the logarithmic decrement here loses its original significance, 
