HISTORY OF MAGNETISM.
It is said that the word magnetism is derived from the name of a Greek
shepherd, called Magnes, who once observed on Mount Ida the attractive
properties of loadstone when applied to his iron shepherd's crook. It is
more likely that the name came from Magnesia, a country in Lydia, where
it was first discovered. It was also called Lapis Heracleus. Heraclea
was the capital of Magnesia. Loadstone is a magnetic ore or oxide of
iron found in the natural state, and has at some time by natural
processes been rendered magnetic--that is, given the power of attracting
iron, and, when suspended, of pointing to the North and South Poles. The
power of the natural magnet was known at a very early age in the history
of man. It was referred to by Homer, Pythagoras, and Aristotle. Pliny
also speaks of it, and refers to one Dinocares, who recommended to
Ptolemy Philadelphus to build a temple at Alexandria and suspend in its
vault a statue of the queen by the attractive power of "loadstones."
There is also mention of a statue being suspended in like manner in the
temple of Serapis, Alexandria.
It is claimed that the Chinese knew of and used the magnetic needle in
the earliest times and that travelers by land employed this needle
suspended by a string to guide them in their journeys across the country
a thousand years before Christ. Notwithstanding the claims of the
Chinese and Arabians to the discovery of the use of the magnetic needle,
modern authors question whether the ancients were familiar with any
artificial construction of a magnetic needle, however much they may have
studied and used the loadstones. No doubt the loadstone in its natural
state was used by mariners to steer their ships by, long before its
artificial counterpart was invented. In a history of the discovery of
Iceland, by Are Frode, who was born in 1068, it is stated that a mariner
by name of Folke Gadenhalen sailed from Norway in search of Iceland in
the year 868, and that he carried with him three ravens as guides, for
he says, "in those times seamen had no loadstones in the northern
countries." The magnetic needle as applied to the mariner's compass was
known in the eleventh century, as proved by various authors. In an old
French poem, the manuscript of which still exists, the mariner's compass
is clearly mentioned. The author was Guyot, of Provence, who was alive
in 1181.
Like electricity, magnetism has had a long history, but little use was
made of it till modern times beyond that of the mariner's compass. It
can readily be seen what an important factor it was in the science of
navigation. Long after the discovery of the compass needle there were
many perplexing problems arising, and all sorts of theories were
advanced to account for the various phenomena. The variation of the
needle was one of these problems. It is said that Columbus was the first
to discover the variation of the needle, as well as America. This is
disputed, however, as every man's pretensions usually are. However this
may be, Columbus had to invent some plausible theory to account for this
variation to prevent a mutiny among his crew. They were very
superstitious and thought that they were sailing into a new world where
the laws of nature were different from those of Spain. One phenomenon
that disturbed Columbus was the dip of the needle. As we move in a
northerly direction a magnetic needle dips, and it was the observation
of this phenomenon in different latitudes that finally resulted in the
invention of the dipping needle. It is well known that one pole of a
magnetic needle points to the north and the other to the south. In other
words, what is called the north pole of a needle points to one of the
magnetic poles of the earth which is in the direction of the north
pole, though not the same as the geographical pole. A dipping needle
revolves on an axis so that it can point to any declination. If we
should construct one that is perfectly balanced, so as to lie in a
perfectly horizontal direction before it is magnetized, it will dip--in
this latitude--downward toward the north after magnetization. If we keep
moving northward it will continue to dip downward till we come to the
true magnetic pole, when what is called the north pole of the needle
will point directly downward. If we go back to the equator the needle
will lie horizontally again. We call the end of the needle that points
to the north the north pole. It is really the south pole, because unlike
poles attract each other. If the magnetic poles of the earth are at the
north and south geographical poles, the south pole of the needle will
point north. But it is less confusing to call the end of the needle that
points north the north pole. The nomenclature is purely arbitrary.
It was not until it was learned that magnets could be made by
electricity that they became commercially important outside of their use
in navigation. The advent of electricity has brought magnetism to the
front as one of the great factors in our modern civilization. And we
might say with equal force that the discovery of magnetism has brought
electricity to the front. The truth is that they depend upon each
other. Electricity would be robbed of a large part of its importance as
a factor in modern life if it were not for its relation to magnetism.
Even electric lighting would be impossible, commercially, if it were not
for the part magnetism plays in the production of electricity for this
purpose. It could not be successfully carried on with any battery but
the storage-battery, and the storage-battery is dependent upon the
dynamo, and the dynamo is a magneto-electric machine. When we come to
analyze the relation between magnetism and electricity we cannot
separate them without robbing each of a large part of its usefulness.
They are interdependent forces.
As in the case of electricity there have been many theories regarding
magnetism. One philosopher in the old days accounts for the variation of
the compass-needle on the theory that there are two globes, one
revolving within the other, and that any derangement of their normal
movements in relation to each other affects the needle. Evidently there
were cranks in those days as well as now. Another theory of magnetism
was that there were two fluids--a boreal and an austral--one developing
north polarity and the other south polarity. In the next chapter the
nature of magnetism in the light of modern investigation will be
discussed.