
Several times we have used, without definition, the concept of one variable or system being ‘independent’ of another. It was stated that a system, to be state-determined, must be ‘properly isolated’; and some parameters in S. 6/2 were described as ‘ineffective’. So far the simple method of S. 4/12 has been adequate, but as it is now intended to treat of systems that are neither wholly joined nor wholly separated, a more rigorous method is necessary.