Rick didn't know, but he intended to find out. There must be some works on brain physiology in the library. "However, the important modern work started with Berger in the late 1920's. He found that the brain emits a definite pulse of activity, which was then known as the 'Berger rhythm.' "Since then, Berger's work has been very much refined. We now know that the brain actually produces a number of clearly defined electrical rhythms. These rhythms have been used in medical diagnosis of brain injury. Walter, in England, has even developed a machine that will show whether or not people will get along with each other, by analysis of their wave patterns." This was interesting, and Rick intended to find out more about it. But he began to wish Winston would come to the point. "I might add that the rhythmic brain patterns seem to be highly individual. No two are alike, even in identical twins. However, each person shows a pattern that remains fairly constant, even over a period of years. "With this background, you will understand when I report that the EEG's taken of our colleagues brains are completely abnormal. The EEG's were taken while they were awake. Yet, the most prominent pattern is the delta rhythm that is universally associated with sleep and some types of damage to the brain." "Are there any other signs of physical damage?" Hartson Brant asked. "No. All tests are negative. Spinal taps show no concussion, and there is no evidence of trauma of any kind other than psychic. Yet, the delta rhythms persist. In the one case where we have an EEG taken before the--incidents, let's call them--the pattern is entirely different. The scientist had a pattern of a well-known type which bears no resemblance to the EEG taken after the incident." Dr. Morrison leaned forward. "What is your conclusion?" "That our mysterious enemy has somehow caused damage of an unknown kind, by remote means. And that can mean only one thing: The damage was caused electronically, probably by transmission through the air." "Incredible," Weiss muttered, and the sentiment was reflected in the astonished gasps of the others. "Let's consider the implications of Parnell's statement," Hartson Brant said slowly. "If he is correct, then the enemy has devised a means for causing brain disruption in an individual. A transmitted signal would inevitably strike countless others; there can be no such thing as a beam of radiation that strikes one person at a distance while missing all others. Therefore, this beam must affect only one person among many." "But how can a beam be tuned to one person?" Rick asked. "I don't know, Rick." Hartson Brant turned to Winston. "Do you?"