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water for many hours, and another was kept in a sand latli at about 250 C. 

 Ibr liall'an hour or so ; in neither case was there found, on cooling, any change in the 

 elastic condition of the material. 



In Diagram No. VII. there is shown the history of a specimen \\hii-h was dipped 

 in Ixiiling water, whenever an overstraining load had been applied and removed. By 

 tliis means recovery from overstrain instead of taking days, as in Diagram No. III., 

 was effected in a few minutes. The material and the primary overstrain given to it 

 are exactly as in the second example of slow recovery with lapse of time given above ; 

 so that Curves Nos. 1 and 2 of this diagram (No. VII.) should be practically the 

 same as Nos. 1 and '2 of Diagram IV. In order to show that the two pairs of curves 

 are really to a close approximation identical, some of the extensometer readings 

 taken to obtain these curves are compared in the following table. Curve No. 2 in 

 lx>th cases represents the first loading performed after the overstrain which is 

 illustrated by Curve No. 1. 



The readings for the other curves of Diagram VII. need not be tabulated. 



Immediately after the readings for Curve No. 2, Diagram VII., were obtained, the 

 specimen was taken out of the testing machine and placed in a bath of Ix>iling water 

 for 4 minutes. It was then removed, cooled in cold water and re-tested by gradually 

 applying a load of 35 tons per square inch. Curve No. 3 was plotted from the obser- 

 vations taken. This curve is very similar to Curve No. 5 of Diagram IV., and is 

 distinctly straighter than Curve No. 4 of that diagram ; so that 4 minutes at 100 C. 

 has sufficed to produce more perfect recovery than would have resulted from, say, a 

 fortnight's rest at the ordinary laboratory temjxjrature. 



After having been thus recovered and tested, the specimen was turned down in 

 the centre to avoid breaking in the machine grips. About 4 inches at each end were 

 left at the full diameter of 1 inch, a central portion, fully 9 inches long, being turned 

 down to about 0'8 of an inch, and gradually tapered out at each end to the full 



Here elastic behaviour may be said to end. 



