This picture has a further likeness to the naturalist's description made from the fossils of extinct genera of animals. In the latter the animal is made to stand before us. We have the data necessary to infer his habits. But we see him not perfect in his wilderness home of unnumbered ages past. We see him not the pursuer or the pursued; we hear not the fierce growls or the plaintive note of alarm or distress. These we must imagine. So, too, the slowly and peacefully moving train which passes our windows, setting forth the sleeping centuries of this city. There is the emperor in state--dukes in ducal magnificence--knights in armor with horses richly and fancifully caparisoned--citizens in the dress of their times--the various mechanics' and traders' guilds, with their implements, their badges and their banners, with priests thickly scattered through the whole line, which is ever changing as the representatives of one age succeed those of another. The whole is calm and quiet. The fierce contests, the angry broils, private and public--now throwing the whole city into a ferment of innocent alarm, now deluging its streets with blood--the rage of plagues, sealing up the sources of human activity, and causing the stillness of the grave to settle over the scene--all these we must supply; and surely the thoughtful mind is busy in doing this as it contemplates the passing train. We conceive rival claimants for the ducal throne, contending, regardless of dying counsel, until death again settles what death had thrown open to contest. Everything which has ever transpired on the theatre of the world's great empires, may be conceived as enacted on this narrower stage. The difference is less in talents and prowess than in the extent of the field and the numbers of actors.