358 



Messrs. J. C. McConnel and D. A. Kidd. [June 21, 



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large increase in the velocity. But it has further the remarkable 

 effect of transforming a slow retardation into a rapid acceleration. A 

 light tension now reduces the velocity to nearly the old figure. But 

 as soon as the former tension is restored, the acceleration continues 

 till the velocity reaches nearly 2 mm. an hour. It is true that this 

 acceleration was attended by a rising temperature, but it seems far 

 too great to be attributed to that alone. We may fairly conclude 

 that the process of extension itself has sometimes the effect of 

 increasing the apparent plasticity. Reducing the tension by one- 

 third brought down the velocity at once by four-fifths, and, strange 



