The scanning technique of the previous paper permits the visual observation, by photographic recording, of the two basic phenomena of holography, namely, wave interference and wave diffraction. Examples are presented and discussed to explain both the hologram concept and the recent medical development in acoustic holography which provides a real‐time, x‐ray‐like visual presentation of bone structures and tumors in the human body. [References: the author's books,Seeing Sound(Wiley, New York, 1971);Lasers and Holography(Doubleday, New York, 1969); andAcoustic Holography, in the forthcoming Vol. 10 ofPhysical Acoustics(Academic, New York).]