Page:Popular Science Monthly Volume 16.djvu/261

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ern lakes, and how a knowledge of them had then been gained we do not know. It seems certain that no one in ancient times had ascended the river to them. Expeditions were repeatedly sent out with this object, notably one by Nero, which ascended higher than any other, but was finally stopped by impenetrable marshes, apparently in about 9° north latitude. But in ancient as in modern times the problem was finally approached in a different way. Marin of Tyre had furnished Ptolemy with information in regard to the east coast of Africa. Traders had gone as far south as the promontory of Prasum (Cape Delgado), and doubtless information gained there in regard to Madagascar had given rise to the conjecture of lands inclosing the Indian Ocean. But in trading along the coast these men had heard of two lakes in the interior, which were called the sources of the Nile. Ptolemy would seem to have made particular inquiries about these lakes, for he says that a Greek trader had told him that they were farther inland than he had supposed. He accordingly placed them, as seen in our map, in latitudes 6° and 7° south, and longitudes 57° and 65° east, or on either side of the meridian of Alexandria. Information like this was worthy of the greatest geographer of antiquity, and which should not so long have been despised; for it was only when modern explorers, following ancient traditions, went in from the coast of Zanzibar, that they—not solved but resolved the ancient problem of the sources of the Nile.



IT is expected, by nearly all astronomers who have given attention to the subject, that there will be a display of falling stars on or about November 27th next, though the night of the shower may perhaps fall earlier or later, within a week or so either way. The display, should it occur, will possess far more interest than any ordinary shower of shooting stars, or even than the displays which have been witnessed on the night of November 13th-14th, in 1799, 1833, 1866, and other years. For, though we now know that when these showers of Leonides (as the meteors of November 14th-15th are called) occur, the earth is passing through the track of a comet which is followed by uncounted millions of meteors, and the like when on the nights of August 10th, 11th, and 12th the meteors called Perseids are seen, yet the comets corresponding to these longer-known meteoric showers are less interesting to astronomers than the comet along whose track those bodies travel which produced the shower of falling stars seen on the night of November 27, 1872, and which are expected to produce a similar display this year. It was well remarked by M. O. Struve, at the last meeting of the German As-