Manchester Memoirs, Vol. h. (191 1), No. 12. 17 



is indicated by the cooling curve in the diagram. This 

 new constant length was slightly greater than the original 

 length. It would seem, therefore, that rubber possesses 

 the property of "creeping" under changes of temperature 

 in the same way that lead does. 



A further test was made on a similar specimen of 

 rested rubber tape under a constant load of 50 grams, 

 which corresponds to a tension of 167 lbs. per square inch. 

 {Fig. 9.) This test extends throughout the same range 

 of temperature as the previous one, so that the effect of 



Fig. 8. 

 Spread Rubber Tape Rested for 3 Years. 



tension is clearly illustrated by comparing the two with 

 one another. It will be seen that the curves are very 

 similar up to a temperature of 33°C., at which point a 

 sudden bend occurs in both curves. The specimen under 

 tension now begins to expand much more rapidly than 

 the other one, the curve becoming very steep indeed, the 

 rubber apparently'softening and gradually giving way. 



