. 2, will connect her
telephone set with that of operator No. 2; likewise that any operator
may communicate with any other operator by depressing the key bearing
the corresponding number.

=Limitations of Transfer System.= It may be stated that the transfer
system at present has a limited place in the art of telephony. The
multiple switchboard has outstripped it in the race for popular approval
and has demonstrated its superiority in practically all large manual
exchange work. This is not because of lack of effort on the part of
telephone engineers to make the transfer system a success in a broad
way. A great variety of different schemes, all embodying the fundamental
idea of having one operator answer the call and another operator
complete it through a trunk line, have been tried. In San Francisco, the
Sabin-Hampton system was in fairly successful service and served many
thousands of lines for a number of years. It was, however, afterwards
replaced by modern multiple switchboards.

_Examples of Obsolete Systems._ The Sabin-Hampton system was unique in
many respects and involved three operators in each connection. It was
one of the very first systems which employed automatic signaling
throughout and did away with the subscribers' generators. It did not,
however, dispense with the subscribers' local batteries.

Another large transfer system, used for years in an exchange serving at
a time as many as 5,000, was employed at Grand Rapids, Michigan. This
was later replaced by an automatic switchboard.

[Illustration: Fig. 335. Three-Position Transfer Switchboard]

=Field of Usefulness.= The real field of utility for the transfer system
today is to provide for the growth of simple switchboards that have
extended beyond their originally intended limits. By the adding of
additional sections to the simple switchboard and the establishment of a
comparatively cheap transfer system, the simple boards may be made to do
continued service without wasting the investment in them by discarding
them and establishing a completely new system. However, switchboards are
sometimes manufactured in which the transfer system is included as a
part of the original equipment. In Fig. 335 is shown a three-position
transfer switchboard, manufactured by the Monarch Telephone Company. At
first glance the switchboard appears to be exactly like those described
in Chapter XXI, but on close observation, the transfer jacks and signals
may be seen in the