ing or called subscriber's number. Others
are switches controlling the call in its progress and controlling the
switches responsive to the call. These latter switches take positions
independent of the numbers.

In addition to the major switches, there are upon each division four
minor switches termed _registers_. Each consists of an arc of fixed
contacts accompanied by a set of brushes which sweep over the contacts.
Instead of being driven by an electromagnet, the register brushes are
placed under tension of a spring which tends at all times to draw them
forward. They are then restrained by an escapement device similar to a
pallet escapement in a clock, the pallet being controlled by the
register's magnets. When a series of impulses are received by the
register magnets, the pallet is actuated a corresponding number of times
and the register brushes are permitted to move forward under tension of
their powerful propelling spring. Each register is associated with a
major switch, and the register brushes are engaged by a cam upon the
associated major switch, and are restored to normal position against the
tension of their propelling spring, the force of restoration being
obtained from the main shaft.

The electrical clutches which connect and disconnect the movable brushes
of the major switches from the main driving shaft are controlled in all
instances by circuits local to the central office. In some instances
these circuits include relay contacts and are controlled by a relay. In
other instances they are formed solely through switch contacts. In all
cases the control, when from a distance, is received upon relays
suitable for being controlled by the small currents which are adapted to
flow over long lines. In all instances the power for moving a brush is
derived from the main shaft and only the control of the movement is
derived from electromagnets, relays, or other electric sources. In many
instances the clutch circuit is closed through contacts of its own
switch and, therefore, may be closed only when its switch is in some
predetermined position. All of the switches are mechanically powerful
and designed particularly to sustain the wear of long-continued and
oft-repeated usage. This is true also of the moving parts which carry
the brushes and of the journals sustaining those parts.

_The Switches of the Connective Division._ The six major switches of the
connecting division are as follows:

The Primary Connector:--T