MI: .i. MTU; MX Tin-: KKCOVKKY OF IKON KI:<M <ivi,i;.xn;.\i\ 



33 



the manner just explained, was subjected to the treatment recorded in the notes 

 accompanying the diagram, and finally, as shown by Curve No. 8, complete restoration 

 of elasticity was effected. The load was therefore increased until a yield-point was 

 obtained at a stress of about 35 tons ]>er square inch. The recovery from the <>\ 

 strain produced by the passage of this third yield-ioint is shown by means of a curve 

 at A in Diagram No. X. This curve was obtained by plotting amounts of recovery 



Inch 



Diagram No. X. (Time-recovery Curves.) 



Time in minutes, during which specimen mcu kept <tt 60'C. 



measured in the manner described on page 25 (that is, by the diminutions in the 

 extensions produced by the maximum load) against the time taken at 60 C'. to 

 produce the recoveries. This method of measurement is of course faulty, for it has 

 Ix-en shown above that a slight remvery may have occurred, although a greater total 

 elongation has been obtained. But if the nro\ery is tolerably rapid, the method may 

 be justified, for the sake of comparing the rates of recovery at different stages of 

 completion, by means of a time-recovery curve. At C, Diagram X., there is shown a 

 VOL. r\i in. A. F 



