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. Phenomena of Heat. THE LENGTH OF THE DAY AND THE HEAT OF THE EARTH.