first and third positions, just below the line jacks
and signals. There is no transfer equipment in the second position of
this switchboard because the operator at that position is able to reach
the jacks of all the lines and, therefore, is able to complete all calls
originating on her position without the use of any transfer equipment.
Referring to Fig. 301, which illustrates a two-position simple
switchboard, it may readily be seen that if the demands for telephone
service in the locality in which this switchboard is installed should
increase so as to require the addition of more switchboard positions,
this switchboard could readily be converted to a transfer switchboard by
placing the necessary transfer jacks and signals in the vacant space
between the line jacks and clearing-out drops.

[Illustration: CABLE TURNING SECTIONS, BETWEEN A AND B BOARDS Cortlandt
Office, New York Telephone Co.]

CHAPTER XXIV

PRINCIPLES OF THE MULTIPLE SWITCHBOARD

=Field of Utility.= The multiple switchboard, unlike the transfer board,
provides means for each operator to complete, without assistance, a
connection with any subscriber's line terminating in the switchboard no
matter how great the number of lines may be. It is used only where the
simple switchboard will not suffice; that is, where the number of lines
and the consequent traffic is so great as to require so many operators
and, therefore, so great a length of board as to make it impossible for
any one operator to reach all over the face of the board without moving
from her position.

=The Multiple Feature.= The fundamental feature of the multiple
switchboard is the placing of a jack for every line served by the
switchboard within the reach of every operator. This idea underlying the
multiple switchboard may be best grasped by merely considering the
mechanical arrangement and grouping of parts without regard to their
details of operation. The idea is sometimes elusive, but it is really
very simple. If the student at the outset will not be frightened by the
very large number of parts that are sometimes involved in multiple
switchboards, and by the great complexity which is apparent in the
wiring and in the action of these parts; and will remember that this
apparent complexity results from the great number of repetitions of the
same comparatively simple group of apparatus and circuits, much will be
done toward a mastery of the subject.

The multiple switchboard is