Transport: Finder, Feeler, Sounder

From the naval reserve base at Floyd Bennett Field on Long Island one morning last week, a small motor truck containing a radio transmitter set off for an unannounced point an hour's drive away. Hour or so later an American Airlines transport ship took off from the same field. Mounted horizontally just behind the throttles between the pilot and co-pilot was a circular dial face marked off in degrees like a compass. Over this swung an indicator hand. A little tuning picked out the truck's signal, and the hand froze like a pointer on...