Page:Popular Science Monthly Volume 14.djvu/851

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(strait of Gibraltar). Parmenides (born 513 b. c.) is said by Diogenes Laertius to have been the first to assert the sphericity of the earth, and that it is situate in the center of the universe. Strabo credits Parmenides also with having been the first to divide the globe into five zones, or climates as they were called. Passing lightly over the twelve centuries between Ptolemy and the awakening of maritime enterprise which led to the discovery of America, Judge Daly spoke of the large map of the world constructed in Venice in 1457 by Fra Mauro. This map was painted on the wall of a convent in Venice, and it is remarkable not only for the extent of the geographical information it embodies, but for the artistic skill with which it is executed. But even the maps constructed after the time of Columbus and Magelhaens in their delineation of the outline of countries were very defective, and especially in respect to the American Continent. The accessories to geographical knowledge had become so vast, that the work of giving the whole surface of the earth as far as known, in all its details, with any approximation to correctness, was not accomplished till Mercator produced his great map of the world in 1569. In this map he introduced what has ever since been known as Mercator's projection, which not only gives the world in one view, but by a very curious and simple contrivance showed the most effectual way for a vessel to sail on a straight line over a curved surface, and thereby solved what was before one of the most difficult problems in navigation.


Fiords of Glacial Origin on Long Island.—In a paper by Mr. E. Lewis, Jr., read before the Natural History Section of the Long Island Historical Society, some account is given of the fiords which occur on the north side of Long Island, bordering Long Island Sound. In a distance of fifty miles eight of large size occur, penetrating the island to near its center. There are several small ones, remains evidently of large valleys that have been shortened by wearing away of the banks at the sound-shore. The waters of the sound extend into the large valleys from two to six miles, forming safe and beautiful harbors. Fiords, common on rocky coasts, like those of Maine or Greenland, are not frequent in the drift, but those described are singularly perfect in form. They are simply long, deep valleys, from half a mile to a mile broad, their source being in the hill region of the central part of the island. The depth of water in the deep portions of the fiords is from ten to thirty feet, but in a few places where the tidal currents are rapid depths of forty and even fifty feet are found. It is quite certain that sediment is slowly accumulating in the harbors, and is already of considerable thickness. Piles have been driven in one instance through forty feet of soft ooze, and meadows now occupy the upper portions of the valleys. The banks vary in elevation. The general elevation of the country throughout the region may be 150 feet above tide, but it is very undulating, being traversed by a great number of small lateral valleys, which open into the great fiords, chiefly on their easterly side. On the west side of Hempstead Harbor (Roslyn) the bank is 250 feet high, and at one point known as "Beacon Hill" attains an elevation of 307 feet. If to this height we add the depth of water and of sediment in the harbor, it will show that the extreme depth of the valley was not less than 350 feet when its bottom was swept by a glacial stream. There is reason to believe that in several instances these fiord valleys were once continuous southward to the ocean, and the site of glacial rivers flowing in that direction. They probably became filled with débris from the melting glacier, as it finally yielded to a change of climate. From that time the discharge of glacial water was northward through what is now Long Island Sound. The conclusion is, that nearly all the fiords in question are not eroded valleys, but are what remains of river valleys, maintained as such, while the deposit of drift went on. The lateral, or small valleys, referred to were mainly produced by erosion, but why they occur so largely on the easterly side of the great fiords is not explained.


Rainfall and Sun-spots.—The relation between rainfall and sun-spots is a subject which has been discussed with no little heat for a few years past. Of speculation and theory there is more than enough, and it is