from mechanical power. In these, by means of a steam-engine or other
power, a number of coils of wire called the armature are set into
rapid revolution between the poles of powerful electro-magnets. All
currents are caused to flow from the armature in one direction by
means of a contrivance called the commutator. Very successful machines
of this sort are the Gramme machine, the Siemens, and, principally,
the so-called Brush machine. By these the electric light is now
generally produced.


What is a Lightning Rod?

It is a rod of iron placed against a building to protect it from
lightning. Three or four feet of one end is in the moist ground or in
water, while several feet of the other end extend above the highest
part of the building. The upper end of the rod is pointed with copper
or some other metal which will not easily corrode.


By whom was it invented?

By Benjamin Franklin, and first announced by him in his "Poor
Richard's Almanac" for 1753. Franklin was born at Boston, Mass., in
1706. By his talents, prudence, and honesty he rose from humble
beginnings to be one of the foremost men of his time. He was one of
the committee of five chosen by Congress to prepare the "Declaration
of Independence" which he with other patriots afterwards signed.
Towards the close of the year 1776 he was sent as ambassador to the
French Court, and remained in Europe some time. He returned home in
1785, and died at Philadelphia on the 17th of April, 1790.