contact springs lying on the iron plate above the coil. The simplicity
of this device is attractive, and it is of convenience not only from the
standpoint of easy repairs but also from the standpoint of factory
assembly, since by manufacturing standard coils with different
characters of windings and standard groups of springs, it is possible to
produce without special manufacture almost any combination of relay.

[Illustration: Fig. 369. Monarch Relay]

=Assembly.= The arrangement of the key and jack equipment in complete
multiple switchboard sections is clearly shown in Fig. 370, which shows
a single three-position section of one of the small multiple
switchboards of the Kellogg Switchboard and Supply Company. The
arrangement of keys and plugs on the key shelf is substantially the same
as in simple common-battery boards. As in the simple switchboards the
supervisory lamps are usually mounted on the hinged key shelf
immediately in the rear of the listening and ringing keys and with such
spacing as to lie immediately in front of the plugs to which they
correspond. The reason for mounting the supervisory lamps on the key
shelf is to make them easy of access in case of the necessity of lamp
renewals or repairs on the wiring. The space at the bottom of the
vertical panels, containing the jacks, is left blank, as this space is
obstructed by the standing plugs in front of it. Above the plugs,
however, are seen the alternate strips of line lamps and answering
jacks, the lamps in each case being directly below the corresponding
answering jacks. Above the line lamps and answering jacks in the two
positions at the right there are blank strips into which additional line
lamps and jacks may be placed in case the future needs of the system
demand it. The space above these is the multiple jack space, and it is
evident from the small number of multiple jacks in this little
switchboard that the present equipment of the board is small. It is also
evident from the amount of blank space left for future installations of
multiple jacks that a considerable growth is expected. Thus, while there
are but four banks of 100 multiple jacks, or 400 in all, there is room
in the multiple for 300 banks of 100 multiple jacks, or 3,000 in all.
The method of grouping the jacks in banks of 100 and of providing for
their future growth is clearly indicated in this figure. The next
section at the right of the one shown would contain a duplicate set of
mult