It is a curious fact that the world is divided into two great classes,
leaders and followers. Or we might say, originators and copyists; the
former division being very small, while the latter is very large. As
late as 1820 the European philosophers were trying to construct a
telegraphic system based upon two ideas, announced a long time before,
to wit, the use of static or frictional electricity, and a wire for
every letter. It does not seem to have occurred to any one to devise a
code consisting of motions differently related as to time, and to use
simply one wire.
In 1819 Oersted discovered the effect of a galvanic current on a
magnetic needle, and published a pamphlet concerning his discovery. This
stimulated others, and Ampere applied it to the galvanometer the same
year. Arago applied it to soft iron, and here was the germ of the
electromagnet. We see that as far back as 1820 we had the galvanic
battery and the electromagnet, the two great essentials of the modern
telegraph.
However, there remained another great discovery to be made before these
elements could be utilized for telegraphic purposes. One cell of battery
was used, and the magnet was made by winding one layer of wire spirally
around the iron, so that each spiral was out of touch with its neighbor.
Barlow of England, a Fellow of the Royal Society, tried the effect of a
current through a wire 200 feet long, and found that the power was so
diminished that he was discouraged, and in a paper gave it as his
opinion that galvanism was of no use for telegraphing at a distance.
This paper stimulated others, and it was reserved for our own Joseph
Henry, already referred to, to show not only how to construct a magnet
for long-distance telegraphy, but also how to adapt the battery to the
distance. He showed us that by insulating the wire and using several
layers of whirls, instead of one, and by using enough cells of battery
coupled up in series to get more voltage, as we now express it, it was
possible to transmit signals to a distance. He not only set forth the
theory, but he constructed a line of bell-wire 1060 feet long and worked
his magnet by making the armature strike a bell for the signals, which
is the basis of the modern "sounder."
Public-domain text, read in full here on John Shaqi.
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