When we stopped for a red light I watched a young woman in a business suit step between a whiskey bottle head-high, and a bean can about knee-high, and then proceed gingerly waving a colored sphere ahead of her. This sphere, about eighteen inches in diameter, suddenly disappeared. She stopped abruptly and began shouting. Before the traffic light turned green, a man came up with an empty motor oil can and placed it on the sidewalk, under the point she indicated in the air before her. Durstine explained, "When that speck gets large enough to support it, that can will be hung on it. Meanwhile, other people are forewarned that the air over the can is out-of-bounds, so they won't waste detectors on it." As he spoke, the young woman was fishing another "detector" from her purse. It was a limp bit of something which she placed to her lips and inflated until it was a foot-and-a-half in diameter, then she tied off the neck and proceeded down the walk waving it before her in great vertical sweeps. It was as simple as that. Our undoing had been an 85-cent kid's toy. And our salvation was a penny-balloon!