The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

108 MAGNETISM.
den with great rapidity. It has been believed that a
similar distribution of magnetism took place in the transverse section of a magnetic bar; and by a series of magnetic
experiments, results have induced some philosophers to believe that the magnetic power resides on the surface of
iron bodies, and is entirely independent of their mass. On
the other hand some are of the opinion that the magnetic force
commences as a focus at the centre of the mass, and fully culminates at the surface.
COMPONENT PARTS OF THIE MAGNET.
A magnet is considered as composed of minute invisible particles or filaments of iron, each of which has individually the
properties of a separate magnet. It is assumed that there are
two distinct fluids-the austral and boreal; and under the influence of either in a free state, the bar of iron or other metal
will point to the north or south poles of the earth, according to
circumstances. It is within these small particles or metallic
elements that the displacement or separation of the two attractive powers take place; and the particles may be the ultimate
atoms of iron. A magnetic bar may, there- Fig. 6.
fore, as represented in figure 6, be composed
of minute portions, the right hand extremities of each of which possess n pc one speces of
magnetism, and the left hand extremities the A
other species; the shaded ends being sup- Pill
posed to possess boreal, and the light end
austral magnetism. The ends of the bar,
when either straight or U shaped, are charged T ~ 1
with boreal or austral magnetism, and the
ends are called by those respective terms. BT 3
More commonly the ends of the magnet are - i
called the "north" and "south" poles, for g 2
the reasons before mentioned.
These fluids exist in a combined state, and in certain proportions they are united to each molecule or atom of the metal,
from which they can never be disunited except by their decomposition into separate fluids, one of which in a permanent
magnet is always collected on one, and the other on the opposite side of each molecule.
INDUCED MAGNETISM.
In order to communicate magnetism from a natural or artificial magnet, to unmagnetized iron or steel, it is not necessary
that the two bodies should be in contact. The communica