Тhis book is a complete, systematic generalization of the structural theory of distributed systems and will fill a gap with its approach based on the fundamental concepts of a distributed signal and a distributed block. Rules are given for connecting blocks in series and in parallel, and for closure by feedback. The structural theory is extended to complicated interconnected systems, and methods for transforming their block diagrams enable the transfer functions and other characteristics of a system as a whole to be found. The book is divided into three parts: basic theory; applications to concrete problems; and discussion of some important questions in the general theory, concerned with problems in the theory of distributed systems, e.g. controllability, observability, finite control, and stability. The text is illustrated by a variety of problems from thermal engineering, electrical engineering, and building mechanics. In both theory and applications the fundamental concept is the form of an initial boundary value problem (i.e. with homogenous boundary conditions and zero initial conditions); and methods are developed for reducing a problem to standard form. The applications to particular examples are facilitated by a special table which gives impulse response functions (Green's functions) and transfer functions for problems of importance in practice. Included in the table are functions which reduce non-standard problems to standard ones. Readership: Control engineers, applied mathematicians, all lecturers, students, practising scientists and engineers in mechanical, civil, electrical and electronic engineering and related subject areas.