394 Royal Society : — On the Change of Form assumed by 



the upper and lower edges, and also from the centre ; the fibrous 

 condition had remained unchanged, the specific gravity had not 

 altered appreciably, and there appeared to be no deterioration in any 

 part of it. 



Experiment 2. — Two hollow cylinders of wrought iron, 12 inches 

 diameter and ^ inch thick each, and respectively 9 inches and 6 inches 

 deep, were heated to redness, and cooled by half-immersion in cold 

 water twenty times ; for effects see figs. 4 and 5. 



Fig. 4. Fig. 5. 



One-eighth of full size. 



The 9-inch cylinder did not alter on the upper edge, cooled in air ; 

 but the lower edge, cooled in water, contracted *6 inch, and the cir- 

 cumference, at about one inch above the water-line, was reduced 5 5 

 inches ; the internal surface had increased in depth -35 inch. 



The small cylinder diminished * 7 inch on the upper edge, increased 

 *3 inch on the lower edge, and contracted 5*25 inches at about 

 1 inch above the water-line; the internal surface had increased in 

 depth # 3 inch. 



Experiment 3. — A cylinder of very thin wrought iron, so thin that 

 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 

 possible. 



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. 



One-eighth of full size. 



