s own weight. Large pieces, however, do not support
proportionally greater weights, seldom more than one or two times their
own weight.

There are in many places in the world immense beds of magnetic iron-ore.
Such are to be found in the Adirondack region in Northern New York, and
in Chester County, Pennsylvania. The celebrated iron-mines of Sweden
consist of it, and in Lapland there are several large mountains of it.
It must not be inferred, that, because the mineral is called magnetite,
all specimens possess the property called magnetism. The large masses
seldom manifest any such force, any more than ordinary pieces of iron or
steel manifest it: yet any of it will be attracted by a magnet in the
same way as iron will be. The most powerful native magnets are found in
Siberia, and in the Hartz, a range of mountains in Northern Germany.

When a piece of this magnetically endowed ore is placed in a mass of
iron-filings, it will be seen that the filings adhere to it in greatest
quantity upon two opposite ends or sides, and these are named the poles
of the magnet. If the piece be suspended by a string so as to turn
freely, it will invariably come to rest with the same pole turned
towards the north; and this pole is therefore called the north pole of
the magnet, and the action is called the directive action. This
directive action was known to the Chinese more than three thousand years
ago. In traversing those vast steppes of Tartary they employed magnetic
cars, in which was the figure of a man, whose movable, outstretched arm
always pointed to the south. Dr. Gilbert affirms that the compass was
brought from China to Italy in 1260, by a traveller named Paulus
Venetus.

When a piece of hardened steel is rubbed upon a natural magnet, it
acquires the same directive property; and, as the steel could be easily
shaped into a convenient form for use, a steel needle has generally been
used for the needle of a compass. The directive power of the magnet has
been and still is of incalculable value to all civilized nations. Ocean
navigation would be impossible without it, and territorial boundaries
are fixed by means of it; but there are other properties and relations
of a magnet, which have been discovered within the last fifty years,
which are destined to be as important to mankind as that of the compass
has been.

In 1825 William Sturgeon of Woolwich, Eng., discovered that if a copper
wire were wound around a piece of soft iron, a