460 



[March 5, 



Experiment 6. A wrought-iron cylinder exactly similar to the 

 last was cooled by being immersed to two-thirds its depth fifteen 

 times. 



The greatest contraction, amounting to '4 inch, took place a little 

 above the water-line ; the upper edge was *05 inch smaller, and the 

 lower edge *35 inch, while the swellings on the ends were nearly the 

 same as in the last experiment (see fig. 10). 



Fig. 10. 



One-half of full size. The dotted lines indicate the original form. 



The separation of the fibre took place at the fifteenth cooling. 



Experiment 7. Two flat pieces of wrought iron, each 12 inches 

 long, 6 inches deep, and *5 inch thick, were heated and cooled twenty 

 times, one being immersed to half, and the other to two-thirds its 

 depth in water. 



That immersed one-half had contracted or become indented on the 

 ends fully '3 inch ; the other had similar indentations, but to only 



