446 Increased Accuracy in the Use of Bifilar Suspensions. 



In fig. 2 an exerimental curve for T = 5 is drawn to 

 show the form of creep over a longer range. It will be 



Ffr. 2. 



^ 



T IM M//WTS6 



seen that it is only during the primary strain that equation (8) 

 holds, the latter part of the curve being of the type 



y = a + b log t ; 



the dotted line represents the theoretical curve (8), which is 

 identical with the experimental curve for the first fifteen 

 minutes. 



Conclusions, 



Our results indicate" that deflexion measurements which 

 involve the use of bifilar suspensions can be performed with 

 an increased accuracy. 



An examination of the deflexion variation of this suspension 

 during the first few minutes after producing a distortion, 

 shows that the creep can be represented by a curve of the 

 type 



i/ = A + Be- ct 



(where B can be expressed in terms of A and C), although 

 later the character of the movement alters, and is represented 

 by 



y = a + 6 log t. 



This shows that it is at first proportional to the distance from 

 an asymptotic value, and later proceeds approximately in- 

 versely proportional to the lime. It is chiefly with the first 

 part of the curve, during the primary strain, that we have to 

 deal in the case of bifilar suspensions, when seeking a 



