The paper is a critical survey of the design of salient-pole generators in the speed range 300–1 000 r.p.m. with normal peripheral speeds of 15 000 ft/min and over, and runaway speeds of about double that figure. A Table of representative large machines is included.A review of the considerations governing the type of rotor body and the design of the pole fixing is followed by a discussion of the relative merits of laminated and solid poles and their influence on output. The design and construction of field coils is next considered with special reference to recent advances. Damper windings, ventilation and flywheel effect are also considered.The principles underlying the methods of subdividing the stator core and frame are given, and stator windings are considered in detail with particular reference to insulation, transposition and jointing.Bearing developments are reviewed, and the problem of mounting removable thrust collars on vertical shafts is discussed.The influence of various determining factors on the size of machine is analysed, and curves are included to show possible limits of output of future machines in comparison with those of the present day.