Having given me some explanation of the mechanical operation of the apparatus and the way in which it served the purpose of a prolonged optic nerve, the doctor went on to exhibit its powers on a large scale. During the following hour, without leaving my chair, I made the tour of the earth, and learned by the testimony of my senses that the transformation which had come over Boston since my former life was but a sample of that which the whole world of men had undergone. I had but to name a great city or a famous locality in any country to be at once present there so far as sight and hearing were concerned. I looked down on modern New York, then upon Chicago, upon San Francisco, and upon New Orleans, finding each of these cities quite unrecognizable but for the natural features which constituted their setting. I visited London. I heard the Parisians talk French and the Berlinese talk German, and from St. Petersburg went to Cairo by way of Delhi. One city would be bathed in the noonday sun; over the next I visited, the moon, perhaps, was rising and the stars coming out; while over the third the silence of midnight brooded. In Paris, I remember, it was raining hard, and in London fog reigned supreme. In St. Petersburg there was a snow squall. Turning from the contemplation of the changing world of men to the changeless face of Nature, I renewed my old-time acquaintance with the natural wonders of the earth--the thundering cataracts, the stormy ocean shores, the lonely mountain tops, the great rivers, the glittering splendors of the polar regions, and the desolate places of the deserts. Meanwhile the doctor explained to me that not only the telephone and electroscope were always connected with a great number of regular stations commanding all scenes of special interest, but that whenever in any part of the world there occurred a spectacle or accident of particular interest, special connections were instantly made, so that all mankind could at once see what the situation was for themselves without need of actual or alleged special artists on the spot. With all my conceptions of time and space reduced to chaos, and well-nigh drunk with wonder, I exclaimed at last: "I can stand no more of this just now! I am beginning to doubt seriously whether I am in or out of the body." As a practical way of settling that question the doctor proposed a brisk walk, for we had not been out of the house that morning. "Have we had enough of economics for the day?" he asked as we left the house, "or would you like to attend the afternoon session the teacher spoke of?" I replied that I wished to attend it by all means.