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