UNDEK this title, Dr. Ing. Max Jakob last May delivered a course of four lectures under the auspices of the University of London. Constituting as they did a valuable up-to-date review of the experimental work of recent years, the lectures have been prepared for publication since being delivered, and have been printed in extenso in Engineering in eight sections during July-Dec. 1931. The first lecture dealt with the fundamental thermodynamical properties of water and steam, including the mechanical and thermometric direct measurements of pressure, temperature, and volume; the second with the calorimetric, direct measurements of sensible and latent heat contents; the third with the optical measurements by which attempts have been made to determine the specific heat at high temperature, and the development of the steam tables in different countries, while the fourth lecture was a survey of some special problems of steam research such as evaporation, condensation, heat transfer, and heat radiation. Reference was made to the international co-operation on steam research suggested by the British Electrical and Allied Industries Research Association, while at the beginning of his lectures Dr. Jakob paid a tribute to the late Prof. H. L. Callendar, who had, he said, comprehended and mastered the whole science of thermodynamics of water and steam more fully than anyone else in the world.