has passed into a proverb among mankind, but the searching inquiry of modern observers has shown that the expression is correct only with certain limitations. There are two lines on the surface of the earth along which the needle points true north, or where the magnetic and the geographical north correspond. These are called lines of _no variation_, or, as they have also been designated, _agonic lines_, and one is found in the eastern and the other in the western hemisphere. The American line is singularly regular, passing in a south-east direction from the latitude 60° to the west of Hudson’s Bay, across the American lakes, till it reaches the South Atlantic ocean, and cuts the meridian of Greenwich in about 65° south latitude. The Asiatic line of _no variation_ is very irregular, owing, without doubt, to local interferences; it begins below New Holland, in latitude 60° south, it bends westward across the Indian ocean, and from Bombay has an inflection eastward through China, and then northward across the sea of Japan, till it reaches the latitude of 71° north, when it descends again southward, with an immense semicircular bend, which terminates in the White Sea. Hansteen has thought that there are two points in each hemisphere which may be regarded as stronger and weaker poles on opposite sides of the poles of revolution. These are called the magnetic poles of the earth, or by Hansteen _magnetic points of convergence_. These four points are considered to have a regular motion round the globe, the two northern ones from west to east, and the two southern ones from east to west. By the assistance of recorded observations, Hansteen has calculated the periods of these revolutions to be as follows:-- The weakest north pole in 860 years. The strongest north pole in 1746 years. The weakest south pole in 1304 years. The strongest south pole in 4609 years. There are some points of speculation on which Hansteen has ventured which have been smiled at as fanciful; but they may rather indicate an amount of knowledge in the Brahminical and Egyptian priesthood, beyond what we are usually disposed to allow them, and prove that their observations of nature had led them to an appreciation of some of the most remarkable harmonies of this mysterious creation.