[Fig. 12.—The Army wireless station at Fort Gibbons.]

[Fig. 13.—Lightning discharge near Montclair, N. J.]

[Fig. 14.–Photo of double lightning discharge passing to earth near the First Orange Mountain, Montclair, N. J.]

[Fig. 15.—Vertical aerials of the grid, fan and inverted pyramid types.]

[Fig. 16.—A diagram showing pyramid aerial.]

[Fig. 17.–A diagram illustrating the directive action of a flat-top aerial.]

[Fig. 18.—Aerials of the "V" and inverted "L" types.]

[Fig. 19.—A diagram showing the arrangement of a "T" aerial.]

[Fig. 20.—Flat top aerials of the inverted "U" and "T" types.]

[Fig. 21.—Umbrella aerial.]