All conductors become magnetic during the passage of a current through them, and thereby acquire all the properties of a magnet. There are bodies which are natural magnets, and they are called permanent magnets. Those which become magnets only during the passage of a current are called electro-magnets.
Do you know any application of those magnets?
They are employed in a great variety of electrical apparatus, principally in telegraphy.
When was the first telegraph established?
It was made in 1836, being invented by Prof. Steinheil, of Munich, and adopted by the government of Bavaria. It was 12 miles long, and the signals were made by small bells.
Who was the inventor of the telegraph in this country?
Samuel F.B. Morse, who was born at Charlestown, Mass., April 27, 1791. He began life as a painter, but did not give his whole attention to art—chemistry and experiments in electricity and galvanism claiming much of his time. He first conceived the idea of the telegraph in 1832, and exhibited his invention to Congress in 1837. He struggled on with scanty means, and was about to give up in despair when Congress appropriated $30,000 for an experimental line, which was opened on May 12, 1844, between Washington and Baltimore. Prof. Morse died in 1872, but not before he had reaped honors and fortune from his invention.
How rapidly does the electric current travel through the wires?
From experiments made it appears to be about 15,400 miles in a second.
Can more than one message be sent at the same time on the same wire?