MancJiester Memoirs, Vol Iviii. (1914), No. 5. 



V. The Specification of the elements of Stress. Part 

 III. The definition of the dynamical specification 

 and a test of the elastic specification. A chapter 

 in Elasticity. 



By R. F. GWYTHER, M.A. 



( Read and received Feb) tiary loth, 1<)I4.) 



Introduction. 



(i.) In this paper I make use of the phrase " dynamical 

 specification " of stress in an elastic substance, and I 

 contrast or compare it with the " elastic specification " of 

 the stress in the substance, and I must explain at the 

 outset the conceptions from which the idea and the 

 employment of the unusual term has originated. 



The general idea of an elastic body, whether isotropic 

 or crystalline, need not be restated, and it is not proposed 

 to alter in any way the " elastic specification " of stress as 

 derived in the modern method from Green's restatement 

 of the relations between stress and strain. It is, however, 

 convenient to refer to the whole set of relations as 

 " Hooke's Law," although it is not now in the form as 

 stated by Hooke. 



In order to state the point of view taken in this paper 

 in as simple a form as possible, I shall suppose that we 

 are dealing with a homogeneous isotropic elastic solid, 

 and, at a point in this solid statically strained, I shall 

 imagine a strain quadric and an elastic (or Hooke's Law) 



May i6th^ 1914- 



