Science: Electrical Thinking

In a darkened room at the University of Jena, Germany, Professor Hans Berger felt the forehead of his assistant carefully. Finding a proper spot, he punctured the skin, shoved a small silver needle through the interstices of the skull until the tip rested against the outer covering of the cerebral cortex. In the back of the head, he inserted a similar needle, attached a galvanometer to both. Then he stroked the assistant's arm with a glass rod, gave him arithmetic problems to solve.

Dr. Berger was looking for electrical brain waves. Although for 50...