﻿of a Loaded Spiral Spring. 



391 



In addition, if the values of I and p 4 are obtained, E and n 

 can be separately calculated. 



Some observations were taken upon different lengths of 

 one of Salter's steel springs (r= 1*494 cm.), using as the 

 vibrating body one whose moment of inertia could be varied 

 by known amounts from an arbitrary value K by moving- 

 two equal masses in and out along a bar. 



The following is a specimen of the numbers obtained, in 

 C.G.S. measure : — 



Exp. 1.— = 300 w, Z=1408, tf = 78, m=130'5, M=267. 



Moment of Inertia. 

 K + Jmr»+ 586 



„ +1700 



„ +3400 



t r 



t 2 . 



1-473 



1-888 



1-477 



2-505 



1-474 



3-228 



1-475 



3-986 



Whence 



+ 5680 



-j^ =413, 410, 416; mean 413. 



-r^n = 319, 318, 318, 318; mean 318. 



And as a verification we can deduce 



K + 1771^ = 886, 892, 903, 884 ; mean 891, 



which gives for K the value 794. 



The results of the experiments are exhibited in the following 

 table : — 



0. 



I. 



M. 



m. 

 130-5 



1 A - 



B. 



K. 



300 7T 



1408 



267 



1 

 1-77X10 7 



230 XlO 7 



794 



200 it 



939 



267 



87 



1-78 xlO 7 



2-29 XlO 7 



785 



100 7T 



469 



267 



43-5 



1-77 xlO 7 



228 X 10 7 



791 



300 7T 



1408 



533 



1305 



1-79 xlO 7 



228 XlO 7 





The last experiment of the above series was made by 

 attaching an additional mass to the vibrating body, so that x 

 was increased to 125, and of course K was changed. 



Thus we see that the method furnishes consistent results 

 and we deduce for this specimen of steel, 



5 = ?* 2 . 57 



n A 



