To restore the line the operator sends out sufficient additional selective impulses to extend the circuit to the end of the line, and thus brings the grounder into circuit.  The winding of the grounder is connected in such a manner that the next passing impulse throws off its latch, permitting the long spring to contact with the ground spring.  The operator now sends a grounded impulse over the continuous limb L of the line which passes through the restoring coils 7 at all the stations and through the right-hand coil of the grounding device to ground.  The selecting relays are, therefore, simultaneously restored to normal.  The grounder is also energized and restored to its normal position by the same current.

If a party in calling finds that his own line is busy and he cannot get central, he may leave his receiver off its hook.  When the party who is using the line hangs up his receiver the fact that another party desires a connection is automatically indicated to the operator, who then locks out the instrument of the party who has just finished conversation and passes his station by.  When the operator again throws the key, the waiting subscriber is automatically selected in the same manner as was the first party.  If there are no subscribers waiting for service, the stop relay at central will not operate until the grounder end of the line is unlatched, the selecting relays being then restored automatically to normal.

The circuits are so organized that at all times whether the line is busy or not, the movement up and down of the switch hook, at any sub-station, operates a signal before the operator.  Such a movement, when made slowly and repeatedly, indicates to the operator that the subscriber has an emergency call and she may use her judgment as to taking the line away from the parties who are using it, and finding out what the emergency call is for.  If the operator finds that the subscriber has misused this privilege of making the emergency call, she may restore the connection to the parties previously engaged in conversation.

One of the salient points of this Roberts system is that the operator always has control of the line.  A subscriber is not able even to use his own battery till permitted to do so.  A subscriber who leaves his receiver off its hook in order that he may be signaled by the operator when the line is free, causes no deterioration of the local battery because the battery circuit is held open by the switch contacts carried on the ringer.  It cannot be denied, however, that this system is complicated, and that it has other faults.  For instance, as described herein, both sides of the line must be looped into each subscriber’s station, thus requiring four drop, or service, wires instead of two.  It is possible to overcome this objection by placing the line relays on the pole in a suitably protected casing, in which case it is sufficient to run but two drop wires from the nearer line to station.  There are undoubtedly other objections to this system, and yet with all its faults it is of great interest, and although radical in many respects, it teaches lessons of undoubted value.