in its infancy and useless state, but
having grown up to maturity, witness its powers, and see what endeavours
to make it useful have done."

PROFESSOR JOSEPH HENRY'S INVENTION OF THE ELECTRIC TELEGRAPH

[In 1855 the Regents of the Smithsonian Institution, Washington, D.
C., at the instance of their secretary, Professor Joseph Henry,
took evidence with respect to his claims as inventor of the
electric telegraph. The essential paragraphs of Professor Henry's
statement are taken from the Proceedings of the Board of Regents of
the Smithsonian Institution, Washington, 1857.]

There are several forms of the electric telegraph; first, that in which
frictional electricity has been proposed to produce sparks and motion of
pith balls at a distance.

Second, that in which galvanism has been employed to produce signals by
means of bubbles of gas from the decomposition of water.

Third, that in which electro-magnetism is the motive power to produce
motion at a distance; and again, of the latter there are two kinds of
telegraphs, those in which the intelligence is indicated by the motion
of a magnetic needle, and those in which sounds and permanent signs are
made by the attraction of an electro-magnet. The latter is the class to
which Mr. Morse's invention belongs. The following is a brief exposition
of the several steps which led to this form of the telegraph.

The first essential fact which rendered the electro-magnetic telegraph
possible was discovered by Oersted, in the winter of 1819-'20. It is
illustrated by figure 1, in which the magnetic needle is deflected by
the action of a current of galvanism transmitted through the wire A B.

[Illustration: Fig. 1]

The second fact of importance, discovered in 1820, by Arago and Davy, is
illustrated in Fig. 2. It consists in this, that while a current of
galvanism is passing through a copper wire A B, it is magnetic, it
attracts iron filings and not those of copper or brass, and is capable
of developing magnetism in soft iron.

[Illustration: Fig. 2]

The next important discovery, also made in 1820, by Ampere, was that two
wires through which galvanic currents are passing in the same direction
attract, and in the opposite direction, repel, each other. On this fact
Ampere founded his celebrated theory, that magnetism consists merely in
the attraction of electrical currents revolving at right angles to the
line joining the two poles of the