263,210. Automatic Telephone Manufacturing Co, Ltd., (Automatic Electric Co.). Aug. 25, 1925. Automatic and semi-automatic exchange systems; metering.-In a system using temporarily employed register-controllers, when the connection has been set up as far as possible, the release of the register-controller is initiated by an interruption of current flow over the speaking leads due to the operation of the last switch of the train. The release of the register-controller is dependent upon the relapse of a relay thereat included in the out-impulsing circuit, which is broken consequent upon the sending back of the signal from the last switch. In the arrangement described, this signal is constituted by the current interruption over the speaking leads which occurs when the connection is switched through on the last switch being set on a wanted line or on a switch encountering an all trunks busy condition. The register-controlled is released from within on calls comprising the maximum number of numerical digits. Other features of the system described below are claimed in divided Specification 263,467. The invention is described with reference to a network in which the exchanges are of the kind described in Specifications 226,154 and 246,550, in which battery for impulsing is fed forward in the direction of the called party who receives talking current from the first local switch, but provision is made whereby such exchanges may receive calls from exchanges of the kind in which impulsing and speaking current is fed in the direction of the calling party. For such calls special incoming selectors are provided arranged to feed battery in both directions and to reverse the current over the incoming trunk for supervisory purposes. A typical automatic connection between two exchanges of the first type extends over a first code selector, Fig. 8. which becomes associated with a register-controller of the code-translating kind, Fig. 14, a repeater, Fig. 9. for repeating impulses over the outgoing junction by current reversals, an incoming selector, Fig. 11, intermediate selector, Fig. 3, and connector, Fig. 4. Forward loop impulsing is used throughout. A modified connector, Fig. 5, is described in which the switching relay also acts as the change-over relay. For calls to private branch exchanges, rotary connectors, Fig. 6, are provided, in which when a P.B.X. number is called, after the final digit, the circuits of the line relay are changed so that it acts as a stepping relay in conjunction with the rotary magnet to control hunting. Calls to a toll operator's position. Fig. 7, are made directly from the first code selector, Fig. 8, which is so arranged that on such calls a relay 721 connected to the release wire pulls up to cut out the talking condensers and feed relays, the calling party receiving battery feed from the toll position so that the operator may have answering supervision. Calls from a toll board, Fig. 1, are made, for example, over an exchange selector 54, an incoming toll selector, Fig. 2, an intermediate selector, Fig. 3, and a connector, Fig. 4, or a rotary connector, Fig. 6. The connectors are so modified that in automatic connections they control ringing in the usual manner, but when they are used for toll service, the starting of ringing is controlled over a fourth conductor extending from the toll selector, Fig. 2, over extra wipers of the intervening switches. When the connector is taken into use, the ring-cut-off relay locks up, but on the toll operator throwing her ringing key it is short-circuited by earth applied to the fourth conductor by an alternating current relay at the toll selector, Fig. 2. Automatic call to distant exchange subscriber; selection of idle register-controller from first code selector repeater, Fig. 8. A calling party A is extended to an idle first code selector by the line switch LS in known manner. The line and release relays 722, 723 energize, the latter earthing the holding wire through the low resistance bottom winding of switching relay 721 (which remains inert) and energizing a relay 728, which lights a supervisory progress lamp 741 and operates a pilot relay 743, which in turn lights a pilot lamp 745 and closes a time alarm circuit to give a signal in case the seizure of the selector is due to a fault on the subscriber's line. Relay 728 also connects up dial tone received from the register-controller selector, Fig. 14, over lead 1301. The first digit dialled is repeated by relay 722 over lead 1302 to the vertical magnet 1319 of the register-controller selector, the wipers of which are raised and then hunt in the usual manner for an idle register-controller. On the response of the switching relay 1313, the impulse conductor 1302 is extended to the inimpulsing lead 1335 of the seized register-controller, and a circuit is closed over lead 1305 for the lower winding of the impulse relay 729 of the selector repeater, Fig. 8. and for a relay 1345 in the register-controller. Relay 729 energizes change-over relay 726 which prepares the first code selector - repeater for operation, disconnects tho progress lamp 741. and energizes progress lamp 740 and pilot relay 742. Register-controller. This operates in the usual manner with the exception of its release control and the impulse sending switch SS which is illustrated in Fig. 14. The impulses received over the wire 1335 are directed to the exchange and numerical registers by the usual sequence switch which in its third and subsequent positions connects an interrupter to the lead 1341 extending to the sending switch magnet 1360. At the end of the setting of the exchange register, therefore, the sending switch SS is advanced to send the first (and in this case the only) routing digit. At the first step, pick-up relay 1346 is energized, puts a local earth on the release conductor 1336 to ensure the holding of the register-controller during the transmission of this digit, and removes a shunt from the impulse sending contacts 1361, so that at each subsequent step the out-impulsing circuit over lead 1305 is opened. When the second stop conductor is encountered, stop relay 1347 is locked energized, shunts the sending contacts, disconnects the start wire 1341, and closes a restoring circuit for the sending switch magnet 1360 over its own interrupter contacts 1362. After an interval relays 1346, 1347 relapse and the next digit is sent in the same manner. First code selector, Fig. 8. The impulse relay 729 falls back each time the out-impulsing circuit is opened and energizes the vertical magnet 736 over a circuit 758, 780, 773, 766, 779. On the closure of the off-normal springs 734, the stepping relay 727 energizes and locks up over the interrupter springs 769 of the rotary magnet, the circuit of which it prepares. At the end of the first digit, the change-over relay 726 relapses and energizes the rotary magnet 737, which interacts with the stepping relay 727 as usual, until an idle trunk 794 - - 796 is found, when the switching relay 731 pulls up, closes a locking circuit for the upper winding of relay 729, earths the lower conductor 796, and connects the control conductor 1305 to the upper conductor 794. The relapse of relay 726 also disconnects the lamp 740 and relights lamp 741. Reverse-battery repeater, Fig. 9 or Fig. 10. The line relay 803, Fig. 9, energizes over the forward loop and closes parallel circuits for relays 804, 805. Relay 805 is adjusted to open the circuit of switching relay 801 before the relay 804 operates its armature 814. When relay 804 pulls up, it locks to the release wire 795, and connects the upper and lower winding of relay 805 to the outgoing trunk conductors 818, 819 across which the line relay 1001, Fig. 11, of the incoming selector repeater is bridged at the distant end. Each time now that the line relay 803 relapses in respones to subsequent digits sent from the register-controller, it reverses the direction of the current over the forward loop including conductors 818, 819 by putting direct earth and battery on these conductors over armatures 809, 810, at the same time local circuits being closed for the windings of relay 805. In the modified repeater shown in Fig. 10, the line relay 903 is of the usual reversing type, and when first energized reverses the connections to the windings of relay 905. Relay 905 first energizes over its lower winding and the earthed release wire 795, and closes a circuit for relay 904, which locks to the wire 795 and connects the windings of relay 905 to the conductors 818. 819. Subsequent relapses of the line relay 903 reverse the connections of the windings of relay 905 and consequently the direction of current over the forward loop. Incoming selector repeater. Fig. 11. The forward loop across the junction 818, 819 includes both windings of the polarized relav 1001, which operates and energizes a repeating relay 1002, which in turn circuits. for release relay 1003 and relays 1005, 1007. Relay 1007 connects the upper talking condenser and the upper winding of relay 1001 in parallel across the trunk 818, 819 and closes a local circuit for the lower polarizing winding of relay 1001. At each reversal of current over the trunk 818, 819. relays 1001, 1002, 1005 relapse and parallel circuits are closed for the vertical magnet 1915, and for relay 1004 which holds up relay 1007 during relapses of relay 1005. At the first step, the stepping relay 1008 energizes, locks to earth at armature 1046, and prepares the circuit of the rotary magnet 1016, which is energized on the relapse of the change-over relay 1004 and then interacts with relay 1008 in the usual manner until an idle trunk is engaged, when switching relay 1009 energizes and connects relay 1005 and earth respectively to the upper and lower wipers, thereby completing a forward loop circuit over a bridged line relay 201 at the intermediate selecto