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William Aitken
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Individual
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Individual
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Publication of GB191212975ApublicationCriticalpatent/GB191212975A/en
12,975. Aitken, W. June 3. Indicators or annunciator.-The magnet of a telephone indicator 40, Fig. 4, may be provided with an armature 46 projecting through an opening in the magnetic-return 44 to operate a plate 46, which locks a plug after it has been inserted in the switch-board. A pin 47 serves to restore the indicator when a plug is inserted.
GB191212975D1912-06-031912-06-03Improvements in Branch Telephone Exchange Switchboards.
ExpiredGB191212975A
(en)