Wrought Iron when Heated and then Cooled, 



395 



Experiment 4. — Two wrought-iron cylinders, exactly similar to 

 those used in experiment 2, were heated and cooled by^ being im- 

 mersed to two-thirds their depth in water twenty times. 



The upper edge of the large cylinder was reduced 2*1 inches, and 

 the lower edge *9 inch ; it contracted 5*9 inches at about an inch above 



Fig. 7. Fig. 8. 



WL 



One-eighth of full size. 



the water-line, and the inside surface had increased in depth "35 inch 

 (see fig. 7). 



The upper edge of the small cylinder was reduced in circumference 

 3*6 inches and the lower edge '65 inch, while the greatest contrac- 

 tion at about one inch above the water-line was 4 # 6 inches ; and the 

 internal surface had increased *15 inch in height (see fig. 8). 



Experiment 5. — A solid cylinder of wrought iron, 3 inches in dia- 

 meter and 6 inches deep, was heated and cooled by being immersed 

 half its depth in water fifteen times. 



The greatest contraction took place a little above the water-line 

 and on the lower edge, being in each case *45 inch ; the upper edge 

 was reduced only *1 inch. 



A swell of metal took place on the two ends, but was greatest on 

 the bottom, or that cooled in water, being '15 inch in height. 



The fibre of the iron opened at the fifteenth cooling (see fig. 9). 



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). 



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 

 one-half the amount. They were both turned up into the form of 

 an arc, had thickened on their upper edges, and increased ■ 1 inch in 

 thicknesswherethecontractionsontheendstookplace(seefigs. 1 1 & 12). 



2D 2 



