13,973. Automatic Telephone Manufacturing Co., [Automatic Electric Co.]. June 15. Automatic and semi - automatic exchange systems. - Two-coordinate numerical selectors having a continuous movement instead of the usual step-by-step action are provided with additional wipers engaging special sets of bank contacts which can be given a distinguishing potential so that the selector is positioned in each direction' by a hunting operation. The invention is described as applied to a semiautomatic system in which a calling subscriber A is connected by a line switch C to an idle plug P, which the operator inserts in the jack J of a connector E and then adjusts the latter by means of her keyboard T, the keys of which serve to carth one or more of a number of wires 144 leading to two sets of special testing-contacts b, c, Fig. 2, in the path of two additional wipers 109, 110 of the connector. Construction of connector. The connector described in the Specification 13,970/12 is modified for the purpose of the present invention by providing an additional pair of wipers 109, 110, Fig. 7, on the selector shaft, which co-operate with fixed vertical and horizontal rows of contacts b, c. The wiper 109 is mounted loosely between two collars 189, 190 so that it moves vertically with the switch but does not rotate therewith. Similarly, the wiper 110 rotates with the switch but does not partake in its vertical movement. General operation of system. When the subscriber A removes his receiver, his line switch C operates in the manner described in Specifications 26,301/06 and 1419/10 and connects his line 111, 112 to a relay 102, which lights up the call lamp 105. The operator enquires the connexion wanted, and inserts the plug P in a suitable jack J, thus energizing a cut-off relay 104, which extinguishes the lamp 105 and provides a fresh ground for the hold-on winding 79 of the line switch C. The insertion of the plug P also connects a polarized supervisory relay 103, Fig. 1, in circuit with a relay 130, Fig. 2, the circuit including the contacts of a reversing-relay 158, which is not energized until the wanted subscriber replies. The direction of the current in the relay 103 is such that the lamp 106 is lighted until the subscriber replies, and again when he replaces his receiver. If the wanted subscriber is No. 23, the operator first depresses her second key T, thus grounding through the key-locking magnet 108 the first and second of the leads 144. The wiper 109 is normally in engagement with the first contact b, so that a circuit is completed over a contact 145 for the escapement magnet 25 of the connector, and this circuit is maintained as long as the wiper 109 engages a grounded contact. The connector shaft is thus moved downwards, as described in the preceding Specification 13,970/12, until the magnet 25 is de-energized, the magnet 108 being also de-energized at this point to release the key. As soon as the highspeed spindle is arrested, a contact 44 closes a circuit through an off-normal contact 60 for (1) a self-locking relay 150, which connects the escapement magnet 25 to the wiper 110 instead of the wiper 109, and (2) a relay 38 which releases a catch so as to prevent further downward movement of the switch shaft. The operator then depresses the third key T for the units digit, thus grounding the first three leads 144 and energizing the escapement magnet 25 over the wiper 110. The downward movement of the switch being prevented, a rotary movement is given to the switch as described in Specification 13,970/12, until the wiper 110 engages an unearthed contact, when the magnets 108, 25 are de-energized, and the connector comes to rest, the relay 38 being again energized over the contacts 44, 60. The selector trunk is thus connected through to the wipers 10, 11, and a circuit is closed for the cut-off winding 159 of the called subscriber's line switch. Busy test, busy signal, and supply and control of ringing-current. These operations are effected in substantially the same manner as described in the last-named Specification. Release. When the calling subscriber replaces his receiver, the relay 102 de-energizes and lights the lamp 105. Similarly, when the called subscriber hangs up, the pole-changing relay 158 reverses the battery connexions to the polarized relay 103, which lights the lamp 106. The removal of the plug P (1) de-energizes the relay 104, which opens the circuit of the holding- winding 79 of the line switch C, and (2) opencircuits the relay 130, Fig. 2, which energizes the restoring-solenoid 30 of the connector.