The unification of nations, of ideas, of languages, had brought about also that of weights and measures. No nation had resisted the universal adoption of the metric system, based upon the dimensions of the planet itself. A single kind of money was in circulation. One initial meridian ruled in geography. This meridian passed through the observatory of Greenwich, and at its antipode the day changed its name at noon. [Illustration: “VOYAGES WERE MADE PREFERABLY BY AIR-SHIPS.” ] Nations which we call modern had vanished like those of the past. France had disappeared in the twenty-eighth century, after an existence of about two thousand years. Germany disappeared in the thirty-second; Italy in the twenty-ninth; England had spread over the surface of the ocean. Meteorology had attained the precision of astronomy, and about the thirtieth century the weather could be predicted without error. The forests, sacrificed to agriculture and the manufacture of paper, had entirely disappeared. The legal rate of interest had fallen to one-half of one per cent. Electricity had taken the place of steam. Railroads and pneumatic tubes were still in use, but only for the transportation of freight. Voyages were made preferably by dirigible balloons, aeroplanes and air-ships, especially in the daytime. This very fact of aerial navigation would have done away with frontiers if the progress of reason had not already abolished them. Constant intercourse between all parts of the globe had brought about internationalism, and the absolutely free exchange of goods and ideas. Custom-houses had been suppressed. The telephonoscope disseminated immediately the most important and interesting news. A comedy played at Chicago or Paris could be heard and seen in every city of the world. Astronomy had attained its end: the knowledge of the life of other worlds and the establishment of communication with them. All philosophy, all religion, was founded upon the progress of astronomy. Marvellous instruments in optics and physics had been invented. A new substance took the place of glass, and had yielded the most unexpected results to science. New natural forces had been conquered.