In the magnetic atlas which accompanies M. Hansteen’s work there is a variation chart for 1787, showing the magnetic force at that period. In this chart the western line of no variation, or that which passes through all places on the globe when the needle points to the true north, begins in latitude 60° to the west of Hudson’s Bay; proceeds in a southeast direction through the North American Lakes, passes the Antilles and Cape St. Roque, till it reaches the South Atlantic Ocean, when it cuts the meridian of Greenwich in about 65° of south latitude. This line of no variation is extremely regular, being almost straight, till it bends round the eastern part of South America, a little south of the equator. The eastern line of no variation is exceedingly irregular, being full of curves and contortions of the most extraordinary kind, indicating plainly the action of local magnetic forces. It begins in latitude 60° south, below New Holland; crosses that island through its centre; extends through the Indian Archipelago with a double sinuosity, so as to cross the equator three times—first passing north of it to the east of Borneo, then returning to it, and passing south between Sumatra and Borneo, and then crossing it again south of Ceylon, from which it passes to the east through the Yellow Sea. It then stretches along the coast of China, making a semicircular sweep to the west, till it reaches the latitude of 71°, when it descends again to the south, and returns northwards with a great semicircular bend, which terminates in the White Sea. Thus it is demonstrated that in the northern hemisphere the general motion of the variation lines is from west to east, in the southern hemisphere from east to west.