International Library of Technology · Scranton, International Textbook Co. · leaf 206
ough the filament. , This current isgradually increased as the exhaustionprogresses, and, by heating the fila-ment, drives out any air that may havebeen absorbed by the carbon. Theoperator can tell by the performance ofthe lamp when the proper degree ofexhaustion has been reached, and sealsup the… … §16 ELECTRIC LIGHTING. 9
Electrical engineering
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