1913-] AUSTIN— ENERGY IN RADIOTELEGRAPHY. 409 



tended to verify the general accuracy of our formula. The new 

 series of experiments has been made in connection with the high 

 power naval station at Arlington, Va. This station was equipped 

 by the National Electric Signaling Co. with a lOO-K.W. rotary gap 

 sending set, and was intended for communication with the Canal 

 Zone and with the fleet in the North Atlantic Ocean. The original 

 plan for the antenna as submitted by the National Electric Signaling 

 Co. showed an umbrella supported by a single tower 600 ft. high. 

 The experiments at Brant Rock, however, showed the experts of 

 the Navy Department that an umbrella antenna gave a center of 

 capacity too low for the most effective working. In fact, compara- 

 tive results indicated that the effective height was but little if any 

 higher than the bottom of the umbrella, about 150 ft. in the case of 

 the Brant Rock tower, although the total height was 420. For this 

 reason the Arlington station has been supplied with a platform an- 

 tenna supported by three towers about 400 ft. between centers, one 

 being 600 ft. high and the other two 450 ft. The antenna has been 

 put up in sections and consists of two flat top antennas 350 ft. long, 

 and one 315 ft. long. These are 88 ft. wide with 2;^ wires each. 

 The triangular space between the flat tops is filled in with a trian- 

 gular fan of 25 wires supported independently of the flat top sec- 

 tions. The vertical portion of the antenna consists of a fan of 23 

 wires, 88 ft. wide at the top, narrowing to 10 ft. at 75 ft. above the 

 earth, from which point the wires are brought down in a cage of 

 the Fessenden type. The capacity of this antenna is o.oi m.f., its 

 natural period approximately 2,100 meters and its height to the 

 center of capacity 400 ft. The ground system, consists of a radiat- 

 ing network of wires covering the space between the triangle of 

 towers and extending to some distance outside. The towers were 

 built so that they were insulated from the earth with switches by 

 which they could be connected with the ground net system. With 

 the towers insulated, the antenna resistance exclusive of the in- 

 ductance at a wave-length of 4,000 meters is approximately 8 ohms. 

 Grounding the towers reduces the resistance to 1.8 ohms, and curi- 

 ously enough, no perceptible difference in capacity is observed, nor 

 is the natural period changed by more than a few meters. Theo- 



