The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 188
g peg into the operating Connections. 173 wanted subscribers switch-spring, after testing, locks his home indicator,and also engages him throughout the room. The front barrel of the switch-spring is made larger than the inner or Bline barrel, and thus the test wire is never connected to the body of… … Section of Table.Flat Board with Self-Restoring Indicators. Figure 137. an umbrella spring is employed. This consists of a brass spring letinto the body of the peg. The operators connections beyond the four connection bars (Figure 136,are precisely the same as previously described, and the…
Telephone · Postal service
Internet Archive · Cornell University Library · Public Domain Mark 1.0. Free to use for anything.
