306 PROCEEDINGS OF THE AMERICAN ACADEMY 



Length of wire before applying 1-1 lbs 1.633 metres. 



Original length 1.58 „ 



/2 2.496 R 1.0530 



7^ — 2.667 — -^^^ Ri — L1472 — ''^^^ 



R P . 



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



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 



Expei iment 2a. — These are the results : — 



"We .should expect i?^ to have been 1,197. 



Experiment 3. — In this experiment I used thin copper wire |^ 

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

 though the length inci'eased 2 centimetres. These are the results: — 



It seems that the conductivity of the wire is improved. 



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

 iron rin;'. 



