THIS BOOK is not intended as an abstruse scientific work, but the statement of a new theory, and its comparison with the old ones for the instruction of the masses. It is well said, " every age has its predominant thought." That of Greece was beauty, and she excelled in sculptured grace of statue and temple; that of Rome was power and she conquered the world; that of the sixteenth century was reform, and states and religions were torn into warring fections; that of the eighteenth century was liberty, and nations threw off the thraldom of empire; that of the nineteen-th century is progress, and rivers are bridged, mountains tunneled, and by the swifb wings of electricity time and space are almost annihilated. This is the golden age of opulence; the brilliant and marvelous epoch of electricity. The world has had its age of stone and bronze and iron and silver, but this is the greatest of them all, for now is the full burst of the golden age of mechanical marvels, and electrical wonders. Man has at last imbibed the thought of Deity, and brought to his aid the same plastic and mysterious forces to bless and control the earth, that God used to create and evolve it, when " He said let there be light, and there was light." This age exemplifies the maxim, " Ignorance is the curse of God, but knowledge is the wing wherewith we fly to heaven." Modem science has gained new conceptions of those imponderable forces that physicists have hitherto failed to classify, and which have a commanding sovereignty over matter.