Stress and Strain on the Properties of Matter. 509 



20 kilos, were now put on the lever and taken off again six times 

 in succession. 



T ^r. A 



Ijoad. 



"ITT 



Position of 

 sliding-piece. 



Alteration of 

 resistance in 

 terms of the 

 divisions of the 

 platino-iridium 

 wire. — signifies 

 decrease of 

 resistance on 

 loading. 



Temporary 

 alteration 

 of 



resistance 

 =T. 



Permanent 

 alteration 

 of 



resistance 

 = P. 



T 

 J. 



w 







77 -0 right 







+ 209-0 





% 16 



64-0 „ 



-1*3-0 



-14-0 



+ 210-0 



-0-875 







78-0 „ 











12 



68-0 „ 



-10 



-11-0 



+ 211 



-0-917 







79 -0 „ 











8 



72-0 „ 



- 7-0 



- 65 



+ 210-5 



-0-813 







78' 5 „ 











4 



74-5 „ 



- 4-0 



- 4-5 



+ 211 -0 



-1125 







79-0 „ 











4 



75 -0 „ 



- 4-0 



- 4-0 



+ 211-0 



- 1 -ooo 







79-0 „ 











4 



76-0 „ 



- 3-0 



- 4-0 



+ 212 -0 



-1-000 







80-0 „ 











4 



75-5 „ 



- 4-5 



- 3 5 



+ 211-0 



-0-875 







79 -0 „ 











4 



75-0 „ 



- 4-0 



- 35 



+ 210-5 



-0-875 







78-5 „ 











8 



72-0 „ 



- 6-5 



- 7-0 



+ 211-0 



-0-875 







79-0 „ 











8 



72-5 „ 



- 6-5 



- 7'0 



+ 211-5 



-0-875 







79-5 „ 











12 



70-0 „ 



- 9-5 



-10-5 



+ 212-5 



-0-875 







80-5 „ 











12 



70-5 „ 



-10-0 



-10-5 



+ 213-0 



-0-875 







81-0 „ 











16 



69-0 „ 



-12-0 



-14-0 



+ 215-0 



-0-875 







83-0 „ 











20 



71'0 „ 



-12-0 



-17-5 



+ 220-5 



-0-875 







88*5 „ 











Remarks on Experiments II and III. 



From the third column of Experiment II may be gathered that the 

 resistance of the cobalt decreases up to a certain degree of loading, and 

 then begins to increase. The maximum decrease becomes less and 

 less, at first rapidly, and then more slowly as the permanent strain 

 due to the loading becomes greater and greater until a load of 18 

 kilos.* had been employed. The point of loading at which the 

 maximum decrease occurs becomes higher and higher, gradually 

 increasing from 8 kilos, to about 13 kilos. 



* This does not include the stress due to the weight of the lever. 



