[boyle] 



TENSILE STRESS ON ELECTRICAL RESISTANCE 



177 



To put this in words, — if the increase per cent resistance is plotted on 

 increase per cent stretch, the curve is very nearly a straight line with 



S 

 slope equal to 2. The value of — will not be appreciable below the elastic 



limit, nor will it be comparable with 2 for quite an amount of stretching 



S 

 beyond it. The greatest value obtained for — was about . 125. 



iNC/iciiac pctt CE-frr s'rmc'rcH 



Fig 2. 



On the above assumption, then, the curve of increase per cent resis- 

 tance OQ increase per cent stretch should be a line with initial slope 2. 

 curving slightly to a greater slope for greater values of stretching. 



An examination of the curves will show that this is Just what was 

 obtained, the irregularities being usually at the first part of the curve. 



Sec. TIT.. H)9(i 12 



