that of the current.





CHAPTER IV.

THE ELECTRICITY OF MAGNETISM.


We have already seen how electricity was first produced by the
simple method of rubbing one body on another, then by the less
obvious means of chemical union, and next by the finer agency of
heat. In all these, it will be observed, a substantial contact is
necessary. We have now to consider a still more subtle process of
generation, not requiring actual contact, which, as might be
expected, was discovered later, that, mainly through the medium of
magnetism.

The curious mineral which has the property of attracting iron was
known to the Chinese several thousand years ago, and certainly to
the Greeks in the times of Thales, who, as in the case of the
rubbed amber, ascribed the property to its possession of a soul.

Lodestone, a magnetic oxide of iron (FE3O4), is found in various
parts of China, especially at T'szchou in Southern Chihli, which
was formerly known as the "City of the Magnet." It was called by
the Chinese the love-stone or thsu-chy, and the stone that
snatches iron or ny-thy-chy, and perchance its property of