Patent GB-190321194-A (GB)
Title: Improvements in or relating to the Method of Transmitting Printing Telegraphic Messages over Long Lines, and to the Apparatus therefor.
Inventor: BATTAGLIA-GUERRIERI ANTONIO
Filed: 1903-10-02
Granted: 1904-06-02
Abstract: 21,194. Guerrieri, A. Battaglia-. Oct. 2. Telegraphs.-Relates to improvements in connection with the Hughes' printing - telegraph and like instruments. In order to facilitate the use of such instruments on long lines, and particularly in submarine working, the printing current impulse is preceded by a current-impulse of opposite sign, and may be followed by another. The improvements further comprise (1) the use at the transmitting- station of a comparatively small condenser in combination with a strong battery, a larger condenser being used at the receiving. station ; (2) the use in connection with a mirror galvanometer combined with a selenium cell relay of a condenser the discharge of which brings the galvanometer back to zero with certainty ; (3) a device for enabling the operator at the receiving-station to send "repeat" signals &c. to the transmitter during the intervals between the printing operations ; (4) improvements in means for returning the contact-pins to rest ; and (5) improvements in connection with the printing-magnets. The carriage of the Hughes' apparatus is provided, in addition to the usual rider a, b, Figs. 1 and 3, with a second rider c, d which may overlap the rider a, b at both ends and is designed to send negative impulses before and after each print. The riders a, band c, d serve to actuate sleeves n, m respectively by means of levers h, e and l, q, and these sleeves engage with the levers of oscillating contact-apparatus adapted to send positive and negative currents to line. Fig. 10 shows the connections with battery and line. The line L is normally connected through the contact f<2> with the receiving-instrument, so that in the intervals between transmitting the various characters signals can be received from the distant station. Wheu the sleeve m is lowered by the action of the selected pin on the rider c the line is connected with the negative pole of the battery through f<3>, i<2>. When the sleeve n is also lowered, by the action of the pin on the rider a, the positive pole of the battery is put to line. A fine strip of copper is used instead of paper to prevent the adherence of the armature to the poles of the electromagnet. Fig. 11 shows the re-setting key of the Hughes' apparatus so constructed that electric contact is broken between the contact point e' and the lever a<1>, b<1>, c' when the button d' is pressed. The device is shown diagrammatically at 72, 73 in Fig. 16. The selected pin is returned to the depressed position by means of two rollers moving with the carriage, one of which is in the horizontal plane and pushes the pin inwards, the other being in the vertical plane and serving to depress it. Fig. 16 shows the arrangement adopted for working through an overhead wire or short cable 125. The contactlevers 92, 93 and 94, 95 move in pairs relatively to the contact-blocks 90, 91 under the control of the two riders and sleeves on the carriage. In the position shown, the receiving-instruments are connected to line at both stations. During the transmission of each character, contact is made between 95, 91 at the transmitting-station by the movement of the sleeve m. Negative and positive currents are then sent to line through 92, 93 successively, a portion of the current serving to actuate the local instrument through the branch 97, wire 35, switch 81, core 75 and armature 76 of the electromagnet, commutator blocks 71, 69, electromagnet 78, blocks 70, 68, and detent lever 72 to the earthed terminal 126 of the battery. The current at the distant station may be similarly traced to earth. When the armature leaves the core of the electromagnet, it breaks the above circuit, but a fresh circuit is immediately closed through the resistance 98 and lever 74. Arrangements are also described of a kind adapted for work through longer cables. In these arrangements a small condenser is used in conjunction with a strong battery at the transmitting-station. At the receiving-station, the current passes through a condenser to a mirror galvanometer which throws a spot of light on one or other of two selenium cells associated with a differential galvanometer aud relays which control the Hughes' instrument. Means are provided for substituting a sounder for the printing-instrument. The contact between the spring 79 and lever 74 serves in this case to close a circuit through which a condenser discharges through the mirror galvanometer in order to restore it quickly to the undeflected condition.