[Fig. 42.—High potential humming transformer.]

[Fig. 43.—High potential closed core transformer for wireless work.]

[Fig. 44.—Leyden jar set for oil immersion.]

[Fig. 45.—Oil immersed condenser.]

[Fig. 46.—Diagram showing construction of condenser.]

[Fig. 47.–Tubular condenser.]

[Fig. 48.—Helix.]

[Fig. 49.—Close coupled helix.]

[Fig. 50.—Spark gap.]

[Fig. 51.—Circuit showing tuned transmitting system employing close coupled helix.]