This book on waterwheels deals with the calculation principles and design rules of overshot and backshot waterwheels. The overshot waterwheel is a hydropower machine and impresses with its simple construction, very good insensitivity to contamination, and the possibility of operation without a rake. In addition, this machine has a very good efficiency, which does not drop much even at partial load. Overshot water wheels are assumed to be used for electricity generation. The presentation therefore includes the calculation of the entire arrangement of the waterwheel - gearbox - and generator. Starting from the theoretical description, a design procedure is given, on the basis of which some example wheels are calculated. These example wheels have been in operation in Germany for several years. In addition, experimental results are given for the water wheels, which make the theory used verifiable. New developments are addressed, and illustrations and text have been updated in the translation of the 2nd German edition.