THE TELEGRAPH.

The telegraph consists in a combination of four things, namely:

A battery, which produces a current of electricity.

A line wire, which conducts that current from one point to another.

An electro-magnetic apparatus, which gives out in sounds or sounding strokes all the signals which are made by pulsa tions of that current from a distant point.

THE TELEGRAPH.

Telegraph companies on their long lines use batteries of from twenty to a hundred cells each.

In telegraphy, it is found necessary to use non-conductors wherever the wire is fastened; for this purpose, glass is principally used for outside wires. The glass "insulator" is placed on a wooden pin or "bracket" which is fastened to the pole or building on which the wire is to be supported, after which the wire is strung and tied to the glass with a short piece of iron "tie wire." Inside of offices, hard and soft rubber tubes are used where the wires pass through the windows, and the copper conducting wires are usually covered with a coating of gutta-percha or wrapped with a continuous covering of cotton or silk. The latter is principally used as

NOTE-"The public," says the Electrician, in a description of this apparatus, "considered the eletric telegraph merely as a pure novelty up to the day that it served to bring to justice a man who had committed a horrible crime. The telegraph was then recognized as a communicating ageut of the highest value.

"The dispatches exchanged on that occasion are engraved upon brass plates that are borne by the very instruments that were used at the time. The inscription that the Paddington apparatus bears is as follows:

"On the first of January, 1845, the following telegram was received by this instrument at the Paddington station:

"A murder has just been committed at Salt Hill, and the supposed murderer was seen purchasing a first class ticket for London by the train that left Slough at half past seven o'clock in the evening. He was in the garb of a Quaker, with a long brown coat that reached nearly to his feet. He is in the last compartment of the second first class coach.'

"On the first of January, 1845, the following answer was sent from Paddington:

"The train has just arrived, and a person answering in all repects to the description given by telegraph came out of the compartment named. I pointed the individual out to Police Sergeant Williams. The man entered a New Road omnibus, and Sergeant Williams got in with him.'"

THE TELEGRAPH.

a covering for wires inside the finer instruments. For the handles or knobs to the various instruments hard rubber is generally used.

The operation of a telegraph is not, as many people sup pose, a complicated or difficult matter to understand. The apparatus employed is quite simple, and easily understood.

The battery is the first essential part of a telegraphic apparatus, as it is by the chemical action in the battery that the electric current is first generated. In practical telegraphy this current is made to traverse long or short distances through the conducting medium of metallic wires, and by means of the proper instruments, made to give out tangible results.

The basis of the entire telegraphic mechanism is the Electro-magnet and the transmitting "Key," (see Fig. 271.) The Electro-magnet is constructed as follows: two bars of soft iron, having round heads of hard rubber, thus making spools of each, are joined together by means of a short flat bar of iron similarly soft. The round bars in the spool of the magnet are called cores, the flat connecting bar at the back is called the "back bar" or "heel piece." The movable flat piece of iron in front which is to be attracted by magnetism to the cores, or withdrawn by the spring when no magnetism excites the cores, is called the armature.

A silk or cotton-covered wire is wound in continuous turns about the cores, until the diameter of about an inch and a half is attained, and each core or spool of the magnet contains

THE TELEGRAPH.

a great number of turns of the wire around it. Now, if a current of electricity be sent through this wire, it will, by its passing through the numerous turns, cause the iron cores within to become magnetic and to possess the power of attracting with considerable force any piece of iron brought near to their ends.

The Morse alphabet consists of what are called dots, dashes and spaces. Combinations of these make intelligible signals. Many of the characters will be found to be the reverse of others: such as A is the reverse of N; B of V ; D of U; C of R; Q of X; Z of &; so if the formation of one of these letters be obtained, its reverse is easily mastered. C, E, H, I, O, P, R, S, Z, Y, are merely represented by dots and spaces, and, if due regard be given to them, they will be found very easy to commit to memory.

THE TELEGRAPH.

The first step is to memorize the alphabet, so that each character can be called to mind at will; thus, A, dot and dash; B, dash and three dots; C, two dots, space, dot, etc. The period is the only punctuation mark in frequent use.

A dot (E) is made by a single instantaneons, downward stroke of the key. A short dash (T) is made by holding the key down as long as it takes to make three dots. A long dash (L or cipher) is made by holding down as long as required to make five dots. A cipher is prolonged so as to occupy about the time required for seven dots.

The intervals between dots or dashes in the same letter are called breaks. A space in letters should occupy the time required for a dot and break. The space between letters should occupy the time required for two dots and breaks.

The space between words should occupy the time required for three dots and breaks.

In letters that do not contain spaces, the dots and dashes should follow each other as closely as possible.

The armature of the magnet is attached to a lever, and this lever, which swings on a pivot in the middle, is provided at the end with a pointed pin or screw, which is caused to press upwards against a strip of paper whenever the magnet attracts, and to return to its former position when the attraction ceases. Meanwhile the paper is kept moving steadily forward, so that if the lever-pin is pressed against the paper, for only an instant of time, a short mark or dot appears pressed or embossed into