lating, the fire was
withdrawn, and the whole mass stirred until it was cooled, and the
result was a fine sample of beautiful brown sugar which weighed
forty-three pounds.

Nevertheless food was an important item in their preparations, the
necessities for doing everything in their power to insure the success of
the maritime enterprise. One of the most valuable adjuncts for sailing
is a compass. No attempt had been made to produce the implement, and
when the needs of the expedition were being discussed, Harry was curious
to know the reason why the compass always pointed north and south.

The Professor was very much interested in all electrical phenomena and
replied: "The earth is a huge magnet, and any body which is magnetized
has a north and a south pole. The needle which is also a magnetized body
has, in like manner, a north and a south pole."

"But in what manner does that make the needle point in one way only?"

"Electricity is a very curious thing. While the current unquestionably
moves from one end to the other of a conductor, it also exhibits itself
in the form of rings around the wire. This may not be understood in the
absence of a sketch. For that purpose I make a drawing (Fig. 17) which
shows a conductor (A), through which a current is passing, and this
current is represented by the spiral line (B) which goes around the
conductor."

[Illustration: _Fig. 17. A MAGNET_]

"Well, is magnetism the same as electricity?"

"Both exhibit the same manifestations. Magnetism is nothing more than a
body charged with electricity. The electricity, which appears to travel
around the conductor (A), extends out for some distance from its body,
and produces what is called a magnetic field. This is the case whether
the magnet is a permanent one, like the earth, or whether the conductor
is charged by a dynamo."

"What is the difference between the north and the south pole?"

"There is really no difference. The terms north or south and positive or
negative are mere relative designations, and are distinguished simply by
the movement or direction of the travel of the current. You will
remember when we made the battery, it was shown that the current,
outside of the battery, moved from the positive to the negative pole.
That was merely stating that it moved from the north to the south pole
outside of the earth, and from the south to the north pole inside of the
earth. The current is, therefore, from one magnetic pole to the ot