The  obvious  limitations,  however,  of  the  automatic  system
show  that  the  operators  are  not  to  be  extinguished.  They  can
only  be  reduced — which  raises  the  further  question  :  Shall  they  be
reduced  by  compelling  the  subscriber  to  manipulate  complicated
apparatus  for  local  calls  and  use  the  simple  apparatus  of  his  telephone
for  extra-local  calls,  or  shall  they  be  reduced  by  providing  operators
with  mechanism  which  will  facilitate  their  work  whilst  leaving  the
subscriber  to  obtain  all  calls  in  the  (to  him)  simplest  possible
manner  through  the  telephone  ?

The  latter  method  is  known  as  '  semi-automatic,'  a  term  also
lacking  in  accuracy  but  in  such  general  circulation  as  to  compel
adoption.  All  makes  of  automatic  connecting  and  selecting
contrivances  can  be  used  for  semi-automatic  purposes,  though
some  makers  have  given  more  special  attention  to  the  necessary
variants.  A  machine  which  can  be  worked  by  a  subscriber  for  the
selection  of  a  number  can  obviously  be  worked  by  an  operator  ;  and,
in  view  of  the  fact  that  the  operator  is  a  trained  expert,  the  machine
may  be  made  more  complex  to  cover  a  greater  variety  of  connections.
In  the  completely  manual  system  a  connection  in  one  central
office  group  may  require  to  be  passed  by  the  operator  of  that
central  office  to  the  operator  in  another  central  office.  The  semi-
automatic system  gives  the  first  operator  control  of  a  connecting
mechanism  at  the  second  office  whereby  the  services  of  the  second
operator  are  dispensed  with.  The  existence  of  such  machinery
is  unknown  to  the  subscriber  who  sends  his  call  to  the  operator
through  the  telephone  in  the  usual  way.  The  most  recent  installa-
tion of  the  semi-automatic  system  is  that  at  Newark,  New  Jersey.
