Mr. Morse's telegraph is a recording instrument, that embosses the symbols upon paper, with a point pressed down upon it by an electro-magnet. The symbols that form the alphabet consist of combinations of short and long strokes, which by their repetitions and variations, are made to stand for different letters. Thus a stroke followed by a dot signifies the letter _A_; a stroke preceded by a dot, the letter _B_; a single dot, the letter _E_; and in this manner the whole alphabet is indicated, the number of repetitions in no case exceeding four for each letter. The letters and words are distinguished from one another by a longer space being left between them than between each mark that forms only a part of a letter or of a word. The annexed diagram represents the symbols for the whole alphabet. [Illustration] The mechanism of this telegraph instrument is very simple. The transmitter is merely a spring key, like that of a musical instrument, which, on being pressed down, makes contact with the voltaic battery, and sends an electric current to the receiving station. The operator at the transmitting station, by thus making contact, brings into action an electro-magnet at the station he communicates with, and that pulls down a point fixed to the soft iron lever upon a strip of paper that is kept moving by clockwork slowly under it. The duration of the pressure on the key, whether instantaneous or prolonged for a moment, occasions the difference in the lengths of the lines indented on the paper. A single circuit is sufficient for this telegraph, and a boy who is practised in the use of the instrument will transmit nearly as many words in a minute as can be sent by the double needle telegraph with two wires. The working of Mr. Morse's telegraph, it will be observed, depends altogether upon bringing into action at the receiving station an electro-magnet of sufficient force to mechanically indent paper. Now the resistance to the passage of electricity along the wires diminishes the quantity transmitted so greatly, that at long distances it would be almost impossible to obtain sufficient power for the purpose, if it acted directly. To overcome that difficulty, an auxiliary electro-magnet is employed. The electro-magnet which is directly in connection with the telegraph wire is a small one, surrounded by about 500 yards of very fine wire, for the purpose of multiplying as much as possible the effect of the feeble current that is transmitted. The soft iron keeper, which is attracted by that magnet, is also very light, so that it may be the more readily attracted. This highly sensitive instrument serves to make and break contact with a local battery, which brings into action a large electro-magnet, and as the local battery and the magnet are close to the place where the work is to be done, any required force may be easily obtained. By this means the marks may be impressed on the paper at distances of 400 miles or more apart.