S. E. Catalogue 14 … This Potentiometer is in wide commercial and amateur use. The resistance wire (300 ohms) is Glass-plate Condenser wound on a slate former. Catalogue No. 42 A Glass-plate Condenser designed for use with Spark Coils. The plates are of carefully selected photographic glass. Spark Coil "Amrad "…
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Internet Archive · Fisher - University of Toronto · Public domain (published before 1931). Free to use for anything.
