The Boy's Playbook of Science / Including the Various Manipulations and Arrangements of Chemical and Philosophical Apparatus Required for the Successful Performance of Scientific Experiments in Illustration of the Elementary Branches of Chemistry and Natural Philosophy

by John Henry Pepper

Fig. 219.

Block of wood with four holes; the positive terminal is connected with the holes a and b, the negative with c and d; the hollows are filled with mercury. t t are the wires from the telegraph box, and it is obvious that by dipping them alternately into c b and a d the current is reversed, and the needle deflected right or left at pleasure.

In practice a more elaborate reverser is employed, but to demonstrate the principle the simple block above described is quite sufficient.

With the telegraph placed at the top of a house, or in a distant cottage, and a single cell of Grove's battery, or at most two, for any short distances, with the reverser, messages may be passed with great rapidity from the bottom of the house to the top, or from a mansion to the lodge, it being understood that a battery, reverser, and telegraph, are required at both places where messages are received and answered; but if no answers are required, the battery and reverser are placed at one end of the wire in the house, and the telegraph at the other extremity in the cottage, and earth plates may be arranged to return the current, or another wire used for that purpose.

Whilst lauding to the utmost the invention of the electric telegraph, we must remember "there is nothing new under the sun," and that after all Nature claims the principle of telegraphing, and with the silent gesture, the speaking eye, interpreted and answered by others, she proclaims herself to be the originator of communication by signs. Whilst the language of flowers, and the mournful requirements of the deaf and dumb in the use of the finger alphabet, show how readily man has adopted the important principle, till he has brought it to the highest state of perfection in the electric telegraph.

When the telegraph was first adopted on the Great Western Railway, the most ridiculous ideas were formed of its capabilities, and many persons firmly believed that the wires were used for the purpose of dragging letters and different articles from station to station. "Wife," said a man, looking at the telegraph wires, "I don't see, for my part, how they send letters on them wires, without tearin' 'em all to bits." "Oh, you stupid!" exclaimed his intellectual spouse; "why, they don't send the paper: they just send the writin' in a fluid state."

Fig. 220.

One of the ideas of telegraphic communication.