This thesis is concerned with the analysis of rotary induction motors. Chapter two develops a general field analysis based on a multilayer model of the machine. The analysis is shown to be capable of taking the effects of the discrete nature of skewed rotor bars directly into account. The method is further shown to be able to accommodate asymmetrical stator windings and terminal voltages with ease, and to determine the magnetic fields within the model incidentally. In chapter three, the analysis is verified theoretically by imposing certain classical assumptions and comparing with a conventional equivalent-circuit approach. The effects on classical machines text formulae of relaxing the small-airgap assumption are then examined. Chapter four presents a discussion on some of the practical aspects concerning computer implementation of the field analysis. These include selection of field harmonics and the effects of saturation and rotor skin-effeet. Chapter five applies the field analysis to an experimental machine operating in the first instance as a single-phase motor, and in the second, as an unbalanced two-phase motor. The predicted performance characteristics of this machine are compared with those determined experimentally, to indicate the validity of the method.