458 



[March 5, 



it could not be welded, and was therefore riveted, of the same external 

 dimensions as the 9-inch one of the foregoing experiment, was heated 

 to redness and cooled by half- immersion ten times, in order to test 

 the effect when the thickness of the metal was reduced as much as 



The upper and lower edges were not altered materially, while the 

 greatest contraction took place on the water-line, instead of 1 inch 

 above it as in the last experiment, and amounted to 3*5 inches. The 

 depth measured on the curve had increased * 1 5 inch (see fig. 6) . 



Fig. 6. 



TO; 



One-eighth of full size. 



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. 



One-eighth of full size. 



