upoti the Dimensiotis of Iron and Steel Bars. 235 



to render it extremel}' probable that the shortening effects are 

 proportional cceteris paribus to the square root of the force of 

 tension. 



Experiments with Cast Iron. 



The following experiments were made with a bar of cast 

 iron one foot long and a quarter of an inch in diameter. 



Experiment 18. Cast iron. Tension 80 lbs. 



Experiment 19. Same bar. Tension GS-t lbs. Permanent 

 magnetism to begin with —1*7. 



On comparing Experiment 18 with Experiment 13, it will 

 be observed that the elongation of the cast iron is equal, if not 



