The reviewer knows of no other book that treats so thoroughly the practical and theoretical aspects of artificial light therapy. The range of wave lengths furnished by the various types of lamps and the proper care and testing of the apparatus, as well as the question of dosage, are considered. The author shows the need of artificial light in the big industrial areas and discusses in detail the management and equipment of the light clinics. Case reports are given, and there are many excellent illustrations and plates. The appendix gives the Royal Society chart of electromagnetic waves, and a discussion of Vitaglass, which allows the passage of ultraviolet rays, and of the cadmium photo-electric cell for the detection of ultraviolet waves.