all the branches of experimental philosophy, electricity had been least explored. The attractive power of amber is mentioned by Theophrastus and Pliny, and from them by later naturalists. In the year 1600, Gilbert, an English physician, enlarged considerably the catalogue of substances which have the property of attracting light bodies. Boyle, Otto Guericke, a burgomaster of Magdeburg, celebrated as the inventor of the airpump, Dr. Wall, and Sir Isaac Newton, added some facts. Guericke
Who is this Dr. Wall?
