een pointed out in the
first and the second selectors, all of which are to be found, with some
modifications, perhaps, in the connector, there must be considered the
features in the connector of busy-signal operation, of ringing the
called subscriber, of battery supply to both subscribers, and of the
trunk release operation. These may be best understood by tracing through
the operations of the connector from the time it is picked up by a
second selector until the connection is finally completed, or until the
busy signal has been given in case completion was found impossible. As
in the first and the second selectors, the sequence of operations is
determined by the position of the side switch.

[Illustration: Fig. 395. Connector Side of Line-Switch Unit]

[Illustration: Fig. 396. Circuits of Connector]

_First Position of Side Switch._ The connector in a ten-thousand-line
system is the recipient of the impulses resulting from the third and
fourth movements of the subscriber's dial. Considering the third
movement of the subscriber's dial, the first impulse resulting from it
comes over the rotary side of the line and results in the rotary relay
attracting its armature once. This results in a single impulse through
the private magnet which, however, does nothing because the projection
_5'_ strikes against a projection on the selector shaft. These two
projections interfere only when the selector shaft is in its normal
position. Then follows the series of impulses from the subscriber's
station corresponding to the tens digit in the called subscriber's
number. These pass over the vertical side of the line and through the
vertical relay, energizing that relay a corresponding number of times.

The vertical magnet, as in the case of the first and the second
selectors, is included in the circuit controlled by the vertical relay
and this results in the connector shaft being stepped up to the level
corresponding to the particular tens group containing the called
subscriber's number. It will be noted that the impulses from the
vertical side of the line, which cause this selection, pass through one
winding _13_ of the calling battery supply relay. This relay is operated
by these vertical selecting impulses, but in this position of the side
switch the closure of its local circuits accomplishes nothing.

Immediately after the tens group of selecting impulses over the vertical
side of the line, there follows a single rotary impulse fr