622 



Mr. A. I. Steven on Anomalous 



tension and any kink would be pulled out or flattened out 

 during the operation. 



A series of experiments were now carried out to see whether 

 the same type of curve always resulted when a wire suffered 

 a circular deformation. A number of cylinders were turned 

 of different diameters, and the wire, after it had shown 

 behaviour identical with fig. 1 (2), was rolled up on a definite 

 cylinder, being kept taut by a definite mass hanging at its 

 lower end. The following table illustrates the consistency 

 of behaviour of such a wire during four such tests in the 

 same circumstances — a cylinder of 3 cm. diameter and a 

 tension of 300 grams weight. 



Increase of 

 Tension. 



Extensions in '01 mm. 



Average. 



lbs. oz. 



12 



1 4 



1 12 



2 4 



2 12 

 3 



3 4 

 3 8 



3 12 

 4 



4 4 

 4 8 



I. 



II. 



III. 



IV. 



34 

 63 



89 

 121 

 157 



187 

 221 

 245 

 282 

 325 

 425 

 536 



34 

 62 



87 

 119 

 156 

 177 

 207 

 231 

 265 

 306 

 382 

 549 



35 



62 

 89 

 122 

 162 

 181 

 213 

 244 

 283 

 321 

 398 

 529 



36 

 65 

 92 

 128 

 160 

 183 

 208 

 237 

 271 

 323 

 393 

 500 



35 

 .63 



89 

 122 

 159 



182 

 212 

 239 

 275 

 319 

 399 

 529 



Different wires, however, do not agree so well with each 

 other, even though they are all off the same bobbin. 



The effect of coiling the same wire on a succession of 

 different cylinders was also tried, and after each test for this 

 purpose an intermediate test was applied to see how far the 

 wire had recovered its normal state as in fig. 1 (2). The 

 results are exhibited in fig. 2. The diagram shows the effect 

 of cylinders of 6, 4*5. 3. 1*5 cm. diameter on the wire 

 respectively, the tests being made in that order. The 

 straight line indicates the normal behaviour of the specimen, 

 and is the average of the four tests which immediately pre- 

 ceded the four other curves to see whether the wire had 

 completely recovered. It is obvious that the effect increases 

 with increased curvature, moreover the longitudinal stress 

 applied during the test seems to hasten the recovery of the 

 material to a more homogeneous state. On relieving the 

 load a permanent extension was found to have taken place. 



