message be sent at the same time on the same wire?

Yes; it is possible now to send several messages at the same time.

What is a Cable?

It is a telegraph wire under water. Prof. Morse, in 1842, laid a wire
insulated by a covering of hemp coated with pitch-tar and India-rubber
between Governor's Island and the Battery, New York. Several attempts
were made in other countries.

What was the greatest telegraphic undertaking?

That of connecting Europe with America by a submarine cable spanning
the ocean, which was commenced in 1857 and completed August 5, 1858.

To whom do we owe this grand undertaking?

This honor is entirely due to Mr. Cyrus W. Field. Mr. Field was born
at Stockbridge, Mass., on November 30th, 1819. In 1853 he became
interested in ocean telegraphy, and after many reverses succeeded in
laying the first cable in August, 1858. The message sent by Queen
Victoria to the President of the United States, consisting of 99
words, occupied 67 minutes in transmitting. In September of the same
year this cable ceased to work, but the energy of Field restored
confidence, and another cable was made and laid down in July, 1865,
but after 1200 miles were deposited it was lost. In 1866 another was
made and successfully laid in July. In August the lost cable was found
and spliced, and carried to the western shore.

What is a Dynamo-electric machine?

A machine by which very powerful currents can be obtained directly
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.,