Chapter I. the Four Great Qualities of Electricity Which Make

its modern uses possible.--The universal wire.--Conductors and non conductors.--Electricity an exception in the ordinary Laws of Nature.--A dual nature: "Positive" and "Negative."--All modern uses come under the law of Induction.--Some of the laws of this induction.--Magnets and Magnetism.--Relationship between the two.--Magnetic "poles."--Practical explanation of the action of induction.--The Induction Coil.--Dynamic and Static Electricity.--The Electric Telegraph.--First attempts.--Morse, and his beginnings.--The first Telegraph Line.--Vail, and the invention of the dot-and-dash alphabet.--The old instruments and the new.--The final simplicity of the telegraph.