In a very recent issue of SCIENCE AND INVENTION Dr. Hartman tells of the amazing discoveries he has made in the Mediterranean, off the coast of Sicily, when he went below the sea in his newly constructed steel diving bell, which was designed to withstand a pressure of 2,500 pounds per square inch or a sub-sea depth of about 5,000 feet. During his latest venture below the sea level, Dr. Hartman discovered a prehistoric city--perhaps the Lost Atlantis. Why, then, should it be impossible to assume that there might be cities--even vast cities--submerged miles below the Pacific, for instance, and made habitable? But whatever else might be said, "The Green Girl" is a scientifiction classic that will rank with the best that have ever been published. Though it is a wild, exciting, fantastic tale, it is exceedingly plausible withal. Be sure to read the first installment in this issue. CHAPTER I MAY 4, 1999 At high noon on May 4, 1999, the sun went out! It had risen bright and clear. The summer sky had had an unwonted liquid brilliance. The climbing day-star had shone all the morning with unusual intensity. But just at ten o'clock, an intangible mist obscured the sky! A pale and deepening film stole over the crystal infinity of the heavens! The sky assumed a dull, almost copper tinge, that developed into a ghastly scarlet pall! In five minutes the sky changed from a soft and limpid blue to an intense, darkling scarlet! In the appalling suggestion of blood in the dusky crimson depths, there was a grim omen of the fate of earth! I had got up at dawn for a plunge in the surf, and all the morning I had been wandering about the bit of beach and the strip of virgin woodland behind it, content in the restful, soothing peace of that untouched bit of Nature, rejoicing lazily in the vivid greenness of it, in the fresh odors of earth and plant, in the whisper of the wind in the palms. I lounged on the crisp grass in the cooling shade, living in my sympathy with the life about me, watching the long soft rollers of the green-blue Atlantic surging deliberately toward the crystal whiteness of the sunlit sandy beach. The soft cerulean skies were clear, save for the white wings of occasional airships that glanced in the bright sunshine. The morning had a singularly quiet and soothing beauty. My sleepy soul was in harmony with the distant mellow chime of a church bell. I lay back in the peaceful rest of a man ready to sink lazily into the evening of life. Though I am still an able man of somewhat less than thirty years, I felt that morning none of the energetic exuberance of youth. I felt something of the age and the