Electricity and Magnetism
What is Electricity?—Means of Exciting Electricity—Electrified and Non-Electrified Bodies—Conductors and Non-Conductors of Electricity—Electrical Machines—Positive and Negative Electricity—Velocity of Electricity—Principal Agents in Nature Exciting Electricity—Lightning—Three Forms of Lightning—Sheet and Heat Lightning—Duration of a Flash of Lightning—Places Dangerous in a Thunder Storm—How a Tree Influences Lightning—Lightning Conductors—Their Proper Principle of Construction—Franklin’s Experiment with a Kite—Identity of Lightning and Electricity—Utility of Lightning-Rods—What is Thunder?—What Occasions the Rolling of Thunder?—Aurora-Borealis—Extent of the Aurora—Height of the Aurora—Appearance—Aurora-Borealis Occurs in the Day-Time—What is Galvanism?—How Galvanic Electricity Was Discovered—Construction of a Galvanic Battery—Origin of the Term “Galvanism”—Poles of a Battery—Means by Which Galvanic-Electricity in Quantity Can Be Developed—Different Forms of Galvanic Batteries—Light and Heat Produced by Galvanism—Principles and Processes of Electro-Metallurgy—Magnetism—Natural Magnets—Where Found—Bodies Capable of Being Magnetized—Induction—Magnetic Needle—The Magnetic Compass—Discovery and First Use of the Compass—Electro-Magnetism—When and How Discovered—How Iron Bars Become Magnetic—Horse-Shoe Magnets—Excitation of Magnetism—Morse’s Magnetic Telegraph—Telegraph, Magnetic, Principles of—Intelligence, How Conveyed by—Electric Dynamo and Motors—Wireless Telegraphy—Wireless Telephone—X-Rays