Simple tension with hydrostatic pressure

If the direction of pull is denoted hy the subscript 1 and the two transverse directions by the subscripts 2 or 3 then simple tension with superimposed hydrostatic pressure is characterized by the following statement ... 

Neither of these conditions is easily maintained. In the laboratory it is easier to maintain P and one of the lengths (i ) constant. Thus in order to compute the thermostatic quantities presented in the preceding section, it is necessary to reconstruct these formulae for the case of simple tension with superimposed hydrostatic pressure. We shall not do this in general, but will present the results for one candidate strain energy density. 

The profiles of pendant and sessile bubbles and drops are commonly used in determinations of surface and interfacial tensions and of contact angles. Such methods are possible because the interfaces of static fluid particles must be at equilibrium with respect to hydrostatic pressure gradients and increments in normal stress due to surface tension at a curved interface (see Chapter 1). It is simple to show that at any point on the surface... 

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