182 ELECTRICAL MEASUREMENTS 



by projecting this resistance upon the straight line as indicated, 

 giving l c as the corrected value of the reading. 



Instead of actually making the plot, the corrections are 

 better determined as follows. 



Assuming the wire to be a meter long, the resistance per cm. 



of the uniform wire would be T/T* 



Let (yi) c be the corrected value of y\. 



(2/1 + 2/2)0 be the corrected value of (1/1 -f y 2 ). 



(2/1 -f 2/2 H- . . . -f-i/ n ) c be the corrected value of (y\ + */ 2 + . . . -f y n ). 

 Then 



/ s ^100 RS 



(yi)'i(xj -- 

 (yi + *) iW = IT 



( v _|_ v _|_ _|_ \ ^ 10 _ n ^ 



ifi -r- . . -i- p; 1QO n - 



(S 



) 



The corrections are 

 C\ = 



'#,100 



/2. 



These corrections may be plotted using scale readings as 



tOS*1c*arr\ 



General Discussion of the Wheatstone Bridge. In order to 

 set up and use a Wheatstone bridge to the best advantage, certain 



