An Unabridged Printing To Include Over 70 Illustrations: Historical Sketch - Generalities Concerning Electromagnets - Typical Forms - Polarity - Uses In General - The Properties Of Iron - Methods Of Measuring Permeability - Traction Methods - Curves Of Magnetization And Permeability - The Law Of The Electromagnet - Hysteresis - Fallacies And Facts About Electromagnets - General Principles Of Design And Construction - Principles Of The Magnetic Circuit - Calculation Of Excitation, Leakage, Etc. - Rules For Estimating Magnetic Leakage - Special Designs - Winding Of The Copper - Windings For Constant Pressure And Constant Current - Rules About Winding - Specifications About Electromagnets - Rule About Resistance Of Electromagnet And Battery - Forms Of Electromagnets - Effects Of Size Of Coils - Effect Of Position Of Coils - Effect Of Shape Of Section - Effect Of Distance Between Poles - Position And Form Of Armature - Battery Grouping For Quickest Action - Electromagnetic Magnetism - The Coil And Plunger - Suppression Of Sparking, Etc., Etc.