The Pooles, noted for their lively journalistic explication of technical subjects (Carbon 14, Diving for Science, etc.) present some of the electronic machines at work in modern medicine. Mr. Poole is well placed to do his research -- Director of Public Relations at John Hopkins University, with the pioneering hospital right at hand. Heart stimulators, audiometers, electrodes implanted in brains -- these techniques, as well as many others, are described along with the stories of their development and their possible refinements due to research in progress. Good background in present and futuristic aspects of the always fascinating medical field.