Produced by Anna Hall, Albert László, Matthew Wheaton and the Online Distributed Proofreading Team at http://www.pgdp.net [Illustration: MARCONI WIRELESS TELEGRAPH STATION, CLIFDEN, IRELAND] Photographed at night while sending a message across the Atlantic. The terrific snapping of the electric discharge is heard by one standing near the station, but no light is seen. The strange light given out from the network of wires is invisible to the eye, but is caught by the photographic plate. [Illustration: THE SAME STATION PHOTOGRAPHED BY DAYLIGHT] THE STORY OF GREAT INVENTIONS BY ELMER ELLSWORTH BURNS INSTRUCTOR IN PHYSICS IN THE JOSEPH MEDILL HIGH SCHOOL, CHICAGO WITH MANY ILLUSTRATIONS HARPER & BROTHERS PUBLISHERS NEW YORK AND LONDON MCMX Copyright, 1910, by HARPER & BROTHERS Published November, 1910. _Printed in the United States of America_ CONTENTS CHAPTER I THE AGE OF ARCHIMEDES Archimedes the first great inventor.--The battle of Syracuse.--Archimedes' principle.--Inventions of the ancient Greeks CHAPTER II THE AGE OF GALILEO Galileo and the battle for truth.--The pendulum clock.--Galileo's experiment with falling shot.--The telescope.--Galileo's struggle.--Torricelli and the barometer.--Otto von Guericke and the air-pump.--Robert Boyle and the pressure of air and steam.--Pascal and the hydraulic press.--Newton.--Gravitation.--Colors in sunlight CHAPTER III THE EIGHTEENTH CENTURY James Watt and the steam-engine.--The first steam-engine with a piston.--Newcomen's engine.--Watt's engine.--Horse-power of an engine.--The Leyden jar.--Conductors and insulators.--Two kinds of electric charge.--Franklin's kite experiment.--The lightning-rod.--Galvani and the electric current.--Volta and the electric battery CHAPTER IV FARADAY AND THE FIRST DYNAMO Count Rumford.--Count Rumford's experiment with the cannon.--Davy.--Faraday's electrical discoveries.--Oersted and electromagnetism.--Ampère.--Arago.--Faraday's first electric motor.--An electric current produced by a magnet.--Detecting and measuring an electric current.--An electric current produced by the magnetic field of another current.--Faraday's dynamo.--A wonderful law of nature CHAPTER V GREAT INVENTIONS OF THE NINETEENTH CENTURY Electric batteries.--The dry battery.--The storage battery.--The dynamo.--Siemens' dynamo.--The drum armature.--Edison's compound-wound dynamo.--Electric power.--The first electric railway.--Electric lighting.--The telegraph.--Duplex telegraphy.--The telephone.--The phonograph.--Gas-engines.--The steam locomotive.--How a locomotive works.--The turbine CHAPTER VI THE TWENTIETH-CENTURY OUTLOOK