variation has risen to 20 degrees. Towards the northwest the
easterly variation continually increases, until, in the northern
part of the State of Washington, it amounts to 23 degrees.

When we cross the Atlantic into Europe we find the west variation
diminishing until we reach a certain line passing through central
Russia and western Asia. This is again a line of no variation.
Crossing it, the variation is once more towards the east. This
direction continues over most of the continent of Asia, but varies
in a somewhat irregular manner from one part of the continent to
another.

As a general rule, the lines of the earth's magnetic force are not
horizontal, and therefore one end or the other of a perfectly
suspended magnet will dip below the horizontal position. This is
called the "dip of the needle." It is observed by means of a brass
circle, of which the circumference is marked off in degrees. A
magnet is attached to this circle so as to form a diameter, and
suspended on a horizontal axis passing through the centre of
gravity, so that the magnet shall be free to point in the
direction indicated by the earth's lines of magnetic force. Armed
with this apparatus, scientific travellers and navigators have
visited various points of the earth in order to determine the dip.
It is thus found that there is a belt passing around the earth
near the equator, but sometimes deviating several degrees from it,
in which there is no dip; that is to say, the lines of magnetic
force are horizontal. Taking any point on this belt and going
north, it will be found that the north pole of the magnet
gradually tends downward, the dip constantly increasing as we go
farther north. In the southern part of the United States the dip