In celebration of the 75th anniversary of Thomas Edison's invention of the electric light bulb, this program deals with the history of electricity and its current use in medicine. A film explores electricity's timeline: sparks created from rubbed amber, William Gilbert's study of magnetism, Benjamin Franklin's demonstration of lightening as electricity, Alessandro Volta's first electric battery, and Thomas Edison's 1879 incandescent electric light. Dr. McKusick explains the limitation of stethoscopes to show the need for spectral phonocardiography, a Bell Labs invention which records three-dimensional heart sounds. To create a spectral phonocardiogram, the doctor places a microphone over the patient's chest to record the heart's sounds on magnetic tape, but only the abnormalities are displayed in the final product. An EKG is also made simultaneously for comparison. Lynn Poole notes that research on guided missiles let to the next method of detecting heart disease, ballistocardiography, which is in its experimental stages.