Chapter II.—SPARK COILS. The Construction of Spark Coils. A 1/4-inch

Spark Coil. A 1/2-inch Spark Coil. A 1-inch Spark Coil. A 1 1/2-inch Coil. A 2-inch Coil. Sources of Current. Dry Cells. Storage Cells. Wireless Keys, Etc.