, as we do now, in touching needles and small pieces of iron,
which they made to float upon water, and attracted them about with other
pieces of iron. But it was not long before they found out, as you do
now, another surprising property of this wonderful stone; they observed,
that when a needle had once been touched by the loadstone, if it was
left to float upon the water without restraint, it would invariably turn
itself towards the north. In a short time they improved the discovery
farther, and contrived to suspend the middle of the needle upon a point,
so loosely that it could move about in every direction; this they
covered with a glass case, and by this means they always had it in their
power to find out all the quarters of the heavens and earth."

_Tommy._--Was this discovery of any great use?

_Mr Barlow._--Before this time they had no other method of finding their
way along the sea, but by observing the stars. They knew, by experience,
in what part of the sky certain stars appeared at every season of the
year, and this enabled them to discover east, west, north, and south.
But when they set out from their own country by sea, they knew in which
direction the place was situated which they were going to. If it lay to
the east, they had only to keep the head of the ship turned full to that
quarter of the heavens, and they would arrive at the place they were
going to; and this they were enabled to do by observing the stars. But
frequently the weather was thick, and the stars no longer appeared, and
then they were left to wander about the pathless ocean without the
smallest track to guide them in their course.

_Tommy._--Poor people! they must be in a dreadful situation indeed,
tossed about on such an immense place as the sea, in the middle of a
dark night, and not able even to guess at their situation.

_Mr Barlow._--For this reason they seldom dared to venture out of sight
of the shore, for fear of losing their way, by which means all their
voyages were long and tedious; for they were obliged to make them
several times as long as they would have done, could they have taken the
straight and nearest way. But soon after the discovery of this admirable
property of the loadstone, they found that the needle, which had been
thus prepared, was capable of showing them the different points of the
heavens, even in the darkest night. This enabled them to sail with
greater security, and to venture boldly upon the immense ocean