The technique of observing light shining through the head of an infant is not new, but in view of its value as a diagnostic method and as a prognostic sign, if positive, it has been neglected by neurologists and pediatricians. In 1831 Richard Bright1 described the case of James Cardinal: "If a candle was held behind his head or the sun happened to be behind it, the cranium appeared semitransparent; and this was more or less evident until he obtained his fourteenth year." This person, with a grossly enlarged head, lived to the age of 29, walked at the age of 6 years for the first time, and, in fact, learned to read and write. He was, however, obviously retarded and suffered from epileptic seizures. The autopsy, beautifully illustrated in Bright's text, disclosed a huge cranium filled with clear fluid and only a vestigial cortex present at the base