D—No. 2

19

The Instrument I have adopted, is known as Morse's Electro Magnetic Recording Telegraph. Preparatory to a description of the apparatus it may be advisable to say a few words respecting the construction and application of the battery, which is composed as follows: — A pint Iglass tumbler is filled to about two-thirds of its capacity with a solution of diluted sulphuric acid; within the tumbler is placed a stout cylinder of cast zinc, having at the upper end a projecting arm about three inches in length: within the zinc cylinder is placed a small porous cup made of unglazed earthenware; this cup is nearly filled with nitric acid; a narrow strip of thin platina is soldered to a conducting wire, and the platina immersed in the nitric acid; another conducting wire is attached to the arm of the zinc, and a single cell, as it is termed of Grove's battery, is thus complete. When it is desirable to increase the battery, additional cells are added by soldering a slip of platina to the projecting zinc arm; the platina then dips into the porous cup of the adjoining cell, and so the arrangement may be increased to any desired number of cells, one conducting wire being attached to the first platina in the series, and the other conducting wire being attached to the last projecting zinc arm. In working this form of telegraph, two distinct batteries are used; one is known as the Main battery, consisting of a series of cells, greater or less in number, according to the extent of wire to be traversed, or the resisting force to be overcome; the other, the Local battery, consisting of only one or two cells, is used for operating the pen leaver of the registering Instrument. Each complete Instrument consists of three distinct parts, combined in two galvanic circuits—the Signal, or transmitting key; the Relay, or receiving magnet; and the Register, or recording apparatus. The Key is simply a small horizontal brass lever, about four inches in length, having near its centre a blunt point, below which is placed a similar point called the anvil. The leaver is maintained in a slightly raised position by means of a spring, so that, upon moderately pressing the ivory knob attached to the end of the lever, the two points are brought into contact: upon removing the pressure, the spring instantly raises the lever to its former position. By the use of this portion of the apparatus the main circuit between each office is completed, or broken at pleasure—one termination of the main wire being attached to the leaver itself, and the other to the anvil, it follows that when the two points are apart, the current passing on the main wire is interrupted; and when the contact is made by pressing them together, the circuit is once more completed. By thus interrupting and completing the circuit at certain intervals, and makingcontacts of varied duration, letters, words, and sentences are formed by the aid of the relay and the register, with its fillet of recording paper. The relay is a small Instrument, consisting of an electro magnet, the coils of which'are formed of fine copper wire (No. 35), insulated by a silk covering; the armature of the magnet is attached to an upright lever, at the back of which is fastened a sensitive adjusting spring; the helices or coils containing cores of soft iron, being placed horizontally, and the upright lever with the armature being placed opposite to the faces of the helices. The lever is attracted by the temporary magnetism inducted into the cores by the passing of a galvanic current through the coils, the passage of which current is entirely regulated by the motion of the Signal, or transmitting key. The upper end of the lever carries a connecting point, opposite to which (and so placed that they may come into contact on the armature being attached, and again separated on the back spring of the lever withdrawing the armature), another connecting point is placed. To each of these points is attached the terminations of a single conducting wire from either pole of the local battery, its continuation being attached to the magnet of the register, through which the local current passes back by a return wire to the battery. The Register, or recording Instrument, is a simple arrangement of a few clockwork wheels, which regulate the motion of two rollers slightly pressed together by a spring. The upper roller has a small groove around its centre, to admit the indentation of the point of the pen lever. A weight or spring is employed to move the wheels at a uniform rate, and a narrow slip of white paper is drawn through between the rollers. Nearly on a level with the lower side of the upper-roller is placed a horizontal spring-balanced-lever, carrying at its end next the roller a small upright steel point, or pricker corresponding to the groove, and at its other extremity the armature of an electro magnet, below which is placed the electro magnet itself to which reference was made in describing the relay. One of the conducting wires of the main battery having now been connected with the earth, the other is attached to the anvil of the key, continuing on from the lever to one side of the relay and passing out at the other to the main conducting wire on the tops of the posts, it reaches the distant station, enters at one side of the relay, passes through it to the key, thence again to the earth for its return current. The Signal key being now pressed and released at either station, an effect is instantly produced, for the circuit being completed through the Signal keys and coils of the relays, they, in turn, complete the local circuits through the magnets of the registers, which acting upon the armatures attached to their pen levers, immediately produce an impression upon that portion of the paper pressed into the groove in the upper roller of the point of the steel pricker. A line may be made by a moderately lengthened pressure upon the key; a dot by.a single touch, or instant closing and breaking of the circuit; and a space by a brief pause. Many forms of alphabet are employed, but the one most generally adopted, and at present in use upon the Victorian Lines, is as follows:— Alphabet. b — ... i.. p w. c . .. j —. —. q .. —. x . —.. d —. . k —. — r ..— . — y . . . . c . 1 s .. . z .. . . f .— . m t — & . .. . g . n — . v .. — &c