In the winter of 1856, a heavy ground-swell, brought on by five hours’ gale, scoured away in fourteen hours 3,900,000 tons of pebbles from the coast near Dover; but in three days, without any shift of wind, upwards of 3,000,000 tons were thrown back again. These figures are to a certain extent conjectural; but the quantities have been derived from careful measurement of the profile of the beach.
OCEAN-HIGHWAYS: HOW SEA-ROUTES HAVE BEEN SHORTENED.
When one looks seaward from the shore, and sees a ship disappear in the horizon as she gains an offing on a voyage to India, or the Antipodes perhaps, the common idea is that she is bound over a trackless waste; and the chances of another ship sailing with the same destination the next day, or the next week, coming up and speaking with her on the “pathless ocean,” would to most minds seem slender indeed. Yet the truth is, the winds and the currents are now becoming so well understood, that the navigator, like the backwoodsman in the wilderness, is enabled literally to “blaze his way” across the ocean; not, indeed, upon trees, as in the wilderness, but upon the wings of the wind. The results of scientific inquiry have so taught him how to use these invisible couriers, that they, with the calm belts of the air, serve as sign-boards to indicate to him the turnings and forks and crossings by the way.
Let a ship sail from New York to California, and the next week let a faster one follow; they will cross each other’s path many times, and are almost sure to see each other by the way, as in the voyage of two fine clipper-ships from New York to California. On the ninth day after the Archer had sailed, the Flying Cloud put to sea. Both ships were running against time, but without reference to each other. The Archer, with wind and current charts in hand, went blazing her way across the calms of Cancer, and along the new route down through the north-east trades to the equator; the Cloud followed, crossing the equator upon the trail of Thomas of the Archer. Off Cape Horn she came up with him, spoke him, and handed him the latest New York dates. The Flying Cloud finally ranged ahead, made her adieus, and disappeared among the clouds that lowered upon the western horizon, being destined to reach her port a week or more in advance of her Cape Horn consort. Though sighting no land from the time of their separation until they gained the offing of San Francisco,—some six or eight thousand miles off,—the tracks of the two vessels were so nearly the same, that being projected upon the chart, they appear almost as one.
This is the great course of the ocean: it is 15,000 miles in length. Some of the most glorious trials of speed and of prowess that the world ever witnessed among ships that “walk the waters” have taken place over it. Here the modern clipper-ship—the noblest work that has ever come from the hands of man—has been sent, guided by the lights of science, to contend with the elements, to outstrip steam, and astonish the world.—Maury.
ERROR UPON ERROR.
The great inducement to Mr. Babbage, some years since, to attempt the construction of a machine by which astronomical tables could be calculated and even printed by mechanical means, and with entire accuracy, was the errors in the requisite tables. Nineteen such errors, in point of fact, were discovered in an edition of Taylor’s Logarithms printed in 1796; some of which might have led to the most dangerous results in calculating a ship’s place. These nineteen errors (of which one only was an error of the press) were pointed out in the Nautical Almanac for 1832. In one of these errata, the seat of the error was stated to be in cosine of 14° 18′ 3″. Subsequent examination showed that there was an error of one second in this correction, and accordingly, in the Nautical Almanac of the next year a new correction was necessary. But in making the new correction of one second, a new error was committed of ten degrees, making it still necessary, in some future edition of the Nautical Almanac, to insert an erratum in an erratum of the errata in Taylor’s Logarithms.—Edinburgh Review, vol. 59.