[Fig. 52.—Photo of spark gap.]

[Fig. 53.—Quenched spark gap.]

[Fig. 54.—Diagram of aerial switch.]

[Fig. 55.—Photo of aerial switch.]

[Fig. 56.—Anchor gap.]

[Fig. 57.–Wireless key.]

[Fig. 58.—Photo of wireless key.]

[Fig. 59.—Key and aerial switch.]

[Fig. 60.—Portable receiving set and case.]

[Fig. 61.—Complete receiving outfit.]