om the
subscriber's station which, as in the case of the first and the second
selectors, energizes the rotary relay and causes it to give one impulse
to the private magnet. This impulse is now able, since the shaft has
moved from its normal position, to release the side switch arm one
notch, and the side switch, therefore, moves into its second position.

_Second Position of Side Switch._ It is principally in this second
position of the side switch that the connector selecting function
differs from that of the first and the second selector. There is no
trunk to be hunted, but rather the rotary movement of the connector
wipers must be made in response to the impulses, from the subscriber's
station, which correspond to the units digit in the selected number. The
first impulse corresponding to the fourth movement of the subscriber's
dial is a rotary one, and, as usual, it passes through the rotary relay
winding and this, in turn, gives an impulse to the private magnet. The
private magnet at this time has already released the side switch arm to
its second position, but it is unable to release it further because of a
feather on the wiper shaft--which projects just far enough to engage the
lug _5'_, when the shaft is in its normal angular position--thus
preventing the side switch arm from moving farther than its second
position.

Then follows over the vertical side of the line the last set of
selecting impulses corresponding to the units digit. This, as before,
energizes the vertical relay, but in the second position of the side
switch, it is to be noted, that the vertical relay no longer controls
the vertical magnet; the side switch has shifted the control of the
vertical relay to the rotary magnet. The rotary magnet is, therefore,
energized a number of times corresponding to the last digit in the
called number and the wipers of the connectors are thus brought to the
contacts of the line sought--their final goal. At this point many things
may happen, and the things that do happen depend on whether the called
subscriber's line is idle or busy.

Called-Line Busy:--It will first be assumed that the called line is
busy. The testing operation at the connectors occurs in the second
position of the side switch. If the called line is busy, it will be
either because it is connected to by some other connector or because it
has itself made a call. In the former case the private contacts of that
line in the banks of all the connector