The present book treats the science of heat conduction to an extent to which it can be taught in the specialized departments of Mechanical, Chemical or Electrical Engineering at a German Engineering University. No special prerequisites are assumed, and the mathematical methods employed draw, essentially, on the content of a normal curriculum in the depart­ ments mentioned above. The book is intended for adoption in conjunction with a standard lecture course or as an aid to review before examinations. It should also be found helpful to a practicing engineer in solving problems in heat conduction. As far as the readers are concerned, the book should, above all, show that exact and approximate solutions to answer questions which arise in a very large number of important, practical applications are at their disposal. Further, the book will show that in many cases it is possible to perform first estimates in a very elementary manner before engaging in the derivation of complicated analyticsolutions. It is in this way that we utilize the past results of the great mathematicians of earlier generations who have bequeathed to us a considerable stock of methods and solutions. The application of such methods is illustrated in this book with the aid of examples drawn from various branches of science and technology. In this manner, the wide field of applicability of heat transfer will be made clear.