upo7i the Dimensions of Iron and Steel Bars. 85 



In the foregoing series the discrepancies before adverted to 

 do not make their appearance to any considerable extent, 

 except in the case of the reversion of the magnetic polarity. 

 Taken altogether the series is strikingly confirmatory of the 

 law of elongation already announced. 



The next series of observations was obtained with a piece 

 of soft steel wire one yard long and a quarter of an inch in 

 diameter. Its weight being exactly 8 oz., no reduction of 

 magnetic intensity had to be made for unity of section. 



Experiment 5. 



Experiments 6 and 7 were made with fresh steel bars of 

 precisely the same sort as that employed in the last series. 



Experiment 6. 



