306 PROCEEDINGS OP THE AMERICAN ACADEMY 



Length of wire before applying 14 lbs 1.033 metres. 



Original length 1.58 „ 



li 2.496 R 1.053(3 



7^ = 27(3137" — -^'^^ Ri — ri472 — -'^^^ 



R P . 



Here — < ,— ; and it would .seem that finally iron has been made 



Ri 'i' 



a poorer conductor by stretching. As to the intermediate states of the 

 wire, nothing can be inferred. Later I performed another experiment 

 with better results. It was with the same kind of wire. It would 

 seem to show that the conductivity of iron is improved by stretching. 

 I will call it 



Experiment 2a. — These are the results : — 



"We should expect H^ to have been 1.197. 



Experiment 3. — In this experiment I u.sed thin copper wire ;|:^ 

 millimetre in diameter. 2 lbs. produced no change in the resistance, 

 though the length increased 2 centimetres. These are the results : — 



/ 

 1.476 

 1.5 

 1.566 

 1.576 



It broke under weight 4.3 lbs., and I did not get the final results. 



/2 R 



-p, = .936 -jT- = .946 



'\~ ■'h 



^ ''' . 

 Here - > - 



It seeni.s that the conductivity of the wire is improved. 



I used the same kind of wire in another experiment, which I will 

 call 



Experiment 3a. — The wire stretched in all 31 centimetres, and 

 broke under the full force of 4.3 lbs. The .3 lbs. is the weight of the 

 ii'on ring. 



