hic signal came to him, but
the electric impulse, through his rude apparatus, faded out at a
distance of fifty feet. In 1830 Prof. Joseph Henry, of this country,
constructed a line of wire, one and a half miles in length, and sent a
current of electricity through it, ringing a bell at the farther end.
The following year Professor Faraday discovered magnetic induction.
This, in brief, is the genesis of magnetic electricity, which is the
basis of all that has been accomplished in electrical science.

The first advance after these discoveries was in the development of
the electric telegraph--the discovery in 1837, by the philosopher
Steinhill, that the earth could serve as a conductor, thus requiring
but one wire in the employment of an electric current. Simultaneously
came Morse's invention of the mechanism for the telegraph in 1844,
foreshadowed by Henry in the ringing of bells, thus transmitting
intelligence by sound. Four years later, in 1848, Prof. M. G. Farmer,
still living in Eliot, Me., attached an electro-magnet to clockwork
for the striking of bells to give an alarm of fire. The same idea came
to William F. Channing. The mechanism, constructed simply to
illustrate the idea by Professor Farmer, was placed upon the roof of
the Court House in Boston, and connected with the telegraph wire
leading to New York, and an alarm rung by the operator in that city.
The application of electricity for giving definite information to
firemen was first made in Boston, and it was my privilege to give the
first alarm on the afternoon of April 12, 1852.

At the close of the last century, Benjamin Thompson, born in Woburn,
Mass., known to the world as Count Rumford, was in the workshop of the
military arsenal of the King of Bavaria in Munich, superintending the
boring of a cannon. The machinery was worked by two horses. He was
surprised at the amount of heat which was generated, for when he threw
the borings into a tumbler filled with cold water, it was set to
boiling, greatly to the astonishment of the workmen. Whence came the
heat? What was heat? The old philosopher said that it was an element.
By experiment he discovered that a horse working two hours and twenty
minutes with the boring machinery would heat nineteen pounds of water
to the boiling point. He traced the heat to the horse, but with all
his acumen he did not go on with the induction to the hay and oats, to
the earth, the sunshine and rain, and so get back to the sun. On