sidered in
subsequent chapters), constitute methods of relief from such a condition
in larger exchanges.

[Illustration: Fig. 329. Three-Position Lamp Board]

CHAPTER XXIII

TRANSFER SWITCHBOARD

When the traffic originating in a switchboard becomes so great as to
require so many operators that the board must be made so long that any
one of the operators cannot reach over its entire face, the simple
switchboard does not suffice. Either some form of transfer switchboard
or of multiple switchboard must be used. In this chapter the transfer
switchboard will be briefly discussed.

The transfer switchboard is so named because its arrangement is such
that some of the connections through it are handled by means of two
operators, the operator who answers the call transferring it to another
operator who completes the connection desired.

=Limitations of Simple Switchboard.= Conceive a number of simple magneto
switchboards, or a number of common-battery switchboards, arranged side
by side, their number being so great as to form, by their combination, a
board too long for the ordinary cords and plugs to reach between its
extremities. On each of these simple switchboards, which we will say are
each of the one-position type, there terminates a group of subscribers'
lines so great in number, considering the traffic on them, that the
efforts of one operator will just about be taxed to properly attend to
their calls during the busiest hours of the day. If, now, these
subscribers would be sufficiently accommodating to call for no other
subscribers than those whose lines terminate on the same switchboard
section or on one of the immediately adjacent switchboard sections, all
would be well, but subscribers will not be so restricted. They demand
universal service; that is, they demand the privilege of having their
own lines connected with the line of any other person in the exchange.
Obviously, in the arrangement just conceived, any operator may answer
any call originating at her own board and complete the connection with
the desired subscriber if that subscriber's jack terminates on her own
section or on one of the adjacent ones. Beyond that she is powerless
unless other means are provided.

=Transfer Lines.= In the transfer board these other means consist in the
provision of groups of local trunk lines or transfer lines extending
from each switchboard position to each other non-adjacent switchboard
position. When an oper