During the first half of the twentieth century, before the availability of computerized literature searches, scientists who were working independently often discovered similar measures, phenomena, or relationships. The electrogastrogram (EGG) was discovered independently by at least three investigators: Walter Alvarez, a gastroenterologist; I. Harrison Tumpeer, a pediatrician; and R. C. Davis, a psychophysiologist. On October 14, 1921, after considerable experimentation with rabbits at the University of California in San Francisco, Walter Alvarez recorded the first human EGG. Figure 1.1 shows this EGG, which was recorded from an elderly woman with an abdominal wall hernia. The woman was so thin that Alvarez could observe gastric contractions of 3 min in the upper abdomen that corresponded to the 3cycles/min (cpm) electrical waves that are clearly seen in the EGG recording. Alvarez did not publish additional studies with the EGG during his long and productive career, probably because of the technical difficulties inherent in recording such a weak signal before the development of good vacuum tube amplifiers. I. Harrison Tumpeer, a pediatrician working at Michael Reese Hospital in Chicago, reported in 1926 that while he was attempting to record the EGG, “Alvarez of California published his results.” In a subsequent publication, Tumpeer successfully recorded the EGG from a 5-week-old child who had pyloric stenosis. Tumpeer and his coworkers selected this particular subject because they could observe gastric contractions by simply watching the surface of the skin over the abdomen. Figure 1.2 shows a portion of this EGG. Tumpeer described the EGG as looking like an electrocardiogram (EGG) with a slowly changing baseline. Tumpeer mentioned that cardiologists in 1926 often noted a changing baseline in EGG recordings that they could not explain. Thus, the EGG had been recorded, but perhaps not recognized as such, since the time of the first EGG at the turn of the twentieth century. Tumpeer used limb leads to record his EGG (not abdominal leads) because of his concern that each gastric contraction caused physical displacement of the skin over the child's abdomen. Subsequent studies showed that simultaneous recordings from limbs and abdomen are similar except that the amplitude of the EGG is greatly reduced from recordings from the limb leads.