Then, too, during the three months whose history we have recapitulated, the comet had emerged from regions accessible only to the telescope and had become visible to the naked eye. In full view of the earth it hovered now like a threat from heaven among the army of stars. Terror itself, advancing slowly but inexorably, was suspended like a mighty sword above every head. A last effort was made, not indeed to turn the comet from its path—an idea conceived by that class of visionaries who recoil before nothing, and who had even imagined that an electric storm of vast magnitude might be produced by batteries suitably distributed over that face of the globe which was to receive the shock—but to examine once more the great problem under every aspect, and perhaps to reassure the public mind and rekindle hope by the discovery of some error in the conclusions which had been drawn, some forgotten fact in the observations or computations. This collision might not after all prove so fatal as the pessimists had foretold. A general presentation of the case from every point of view was announced for this very Monday at the Institute, just four days before the prophesied moment of collision, which would take place on Friday, July 13th. The most celebrated astronomer of France, at that time director of the Paris observatory; the president of the academy of medicine, an eminent physiologist and chemist; the president of the astronomical society, a skillful mathematician, and other orators also, among them a woman distinguished for her discoveries in the physical sciences, were among the speakers announced. The last word had not yet been spoken. Let us enter the venerable dome and listen to the discussion. But before doing so, let us ourselves consider this famous comet which for the time being absorbed every thought. CHAPTER II. [Illustration: THE STREET TELESCOPES. ] The stranger had emerged slowly from the depths of space. Instead of appearing suddenly, as more than once the great comets have been observed to do,—either because coming into view immediately after their perihelion passage, or after a long series of storms or moonlight nights has prevented the search of the sky by the comet-seekers—this floating star-mist had at first remained in regions visible only to the telescope, and had been watched only by astronomers. For several days after its discovery, none but the most powerful equatorials of the observatories could detect its presence. But the well-informed were not slow to examine it for themselves. Every modern house was crowded with a terrace, partly for the purpose of facilitating aerial embarkations. Many of them were provided with revolving domes. Few well-to-do families were without a telescope, and no home was complete without a library, well furnished with scientific books.