The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 176
cators and below theswitch-springs, the object being to avoid the cords crossing in front ofand thus obscuring the view of the indicators. The last row of tenindicators are for the ring-off signals, and upon the shelf below theseindicators are placed the ringing and speaking keys. The subscribers… … Earth Figure 129. A B with a small iron armature C carrying a lever D pivoted in front ofit. The lever catches the pivoted shutter E, which falls forward whenthe armature C is attracted. Upon a brass disc, normally covered by theshutter, the subscribers number is painted in black figures. It may…
Telephone · Postal service
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