286 RIGIDITY OF VULCANIZED INDIA-RUBBER.—HEBB. 
There is some lack of regularity in the results of this table 
so far as the determinations with smaller loads are concerned, 
but the divergence from regularity is probably within the limit 
of error of the observations. The results obtained with the 
larger loads exhibit much greater regularity than the results of 
the previous series of observations. The table shows that if the 
tension be increased as rapidly as is consistent with the deter- 
mination of the rigidity at successive stages, the rigidity 
increases with the tension continuously, at first comparatively 
slowly, and finally with greater rapidity. 
The comparatively slow increment of the rigidity under the 
smaller loads would suggest the possibility that the rigidity 
may not appreciably vary with the tension at all under the 
circumstances aimed at in the experiments. For in the light of 
the results of Table IV the larger values of the rigidity under 
the greater loads may be due entirely to the time effect of 
the previous increments of loud. 
