Strains Mechanically Applied. 



171 



In Table VII, I give results for the viscous effect of 

 moderate values of tensile strain, on a plan identical with the 

 above. The pull on the strained wire (the normal being- 

 No, 15) is indicated in the first column in kilogrammes. 

 The maximum pull which these wires will bear wag computed 

 to be between 30 kg, and 50 kg. It was found to be 45 kg. 

 in some cases, experimentally. Inasmuch as I here apply 

 8"4 kg., the pull applied is 17 per cent, to 25 per cent, of the 

 load producing rupture. 



Table VII. — Viscous Effect of Moderate Traction. Soft 

 Steel Wire, 2p = -082 centim. ; /=/' = 30 centim.; 6 = 6^ 

 = 30°: T=-100, 



PuU. 



Time. 



lO^X(0-^')/r. 



PuU. 



Time. 



lO'x(0-0')/V. 



kilogs. 



h m 





kilogs. 



h m 









5 13 





4-8 



5 69 







15 



•00 





6 01 



•00 





17 



•03 





03 



•07 





'20 



•10 





06 



-•07 





24 



•13 





10 



-•13 





29 



•17 





23 



-•27 





35 



•18 





31 



-•40 



2-4 



5 36 



•00 



8^4 



6 32 







37 



•07 





47 



•00 





38 



•13 





7 09 



-•27 





40 



■23 





23 



-■27 





43 



•23 





21 00 



-•07 





48 



•27 











52 



•40 











58 











The results of Tables IV., V., and VI. show the marked 

 influence of the drawn strain in effecting diminution of 

 viscosity clearly. Wires drawn only moderately resilient are 

 of the same lovv order of viscosity as glass-hard wires. 

 Again, if the wires are drawn very resilient the reduction of 

 the viscosity of the originally soft wire is enormous. To 

 eliminate the effect of different degrees of softness I also 

 drew down a wire after heating in air (Table VI.). The 

 results are in accord with Tables IV. and V. 



Some insight into these results is expeditiously obtained 

 by constructing tangents at like time-points of the curves. 

 This is approximately done in the small summary following 

 (Table VIII,), by subtracting the values of (<^ — ^')/t for the 

 beginning and end of the second minute after twisting. 

 Similar values for stretched wire are given in the last two 

 columns, kg. denoting the load. 



