This is a translation of the volume published in Buenos Aires in 1937. As stated in a notice of the book in The Journal July 9, 1938, page 196, the authors record the result of thorough experimental and clinical studies of the mechanism of normal and pathologic heart sounds and their registration by phonocardiographic methods, particularly with the aid of electrical amplification. There are many excellent illustrations. The work will be helpful to those interested in the physiology and pathology of the heart. The appeal to the clinician will be more limited.