Magnetism.
Of what does magnetism treat?
Magnetism treats of the property of magnets.
What is a magnet?
A magnet is a piece of iron ore having the power of attracting iron and steel.
How many kinds of magnets are there?
There are two kinds of magnets: natural magnets, and artificial magnets.
What other name is given to a natural magnet?
It is called a loadstone.
Where are natural magnets or loadstones found?
They are dug out of the earth, and are found most abundantly in Norway and Sweden.
What is an artificial magnet?
An artificial magnet is one made by magnetizing a bar of steel.
How may a bar of steel be magnetized?
A bar of steel, when rubbed on a natural magnet, becomes magnetized.
When the bar of steel is bent in the shape of a horse-shoe, what is it called?
It is then called a horse-shoe magnet, from its shape.
Where does a magnetic bar always point, when it is made to move easily on a pivot?
One end of it always points to the north, and the other end to the south.
What are the ends of the magnet called?
The north end is called the positive, and the south end is called the negative.
What is there curious about the magnet?
The positive end of one magnet always attracts the negative end of every other magnet; but if the two positive or the two negative ends are brought together, they will repel each other.
Why are artificial magnets made of steel?
Because steel will remain magnetized, but iron soon loses the magnetic properties.
What is a compass?
A compass is an instrument containing a magnetic needle, so balanced as to move easily on a pivot.
In what direction does this needle always point?
This needle always points toward the north.
By whom is the compass used?
It is used by travellers to guide them on their journey; by surveyors to mark out the boundary lines between different properties; and by seamen to point out their way across the sea from one place to another.
Before the Mariner’s Compass was invented, seamen were afraid to venture out of the sight of land, for fear of being lost on the ocean; for they then had no means of telling where they were, or in what direction to guide their vessels, so as to reach the land again.