THE OOPS CON.('Low Life' by Luc Sante)

Luc Sante, the author of "Low Life," a book about small-time criminal activity in old New York, left the city six years ago for the Hudson Valley, but the other day he found occasion, from his rustic perch, to comment on the rebirth of the art of the urban swindle. "From all indications, street crime is back in a big way," Sante said.

Among those signs is the recent appearance, in the neighborhood around Columbia University, of a classic tourist con--a sidewalk collision, followed by a dropped (and inevitably broken) object (usually sunglasses), and then a demand for compensatory damages. This updated scam, which preys on the liberal guilt of middle-class college kids, has duped several Columbia students in the past month.

"In terms of archetypes, the student is in the role of the visiting farmer, which was a common role in the nineteenth century," Sante said. "You had the Gold-Brick Scam, which was literally a gold-painted brick, and the Green-Goods Scam, which involved a machine with a crank, where you inserted a blank slip of paper and green currency would come out the other end." He pulled a book off his shelf--"Broadway Racketeers," from 1928--and began naming some more of his favorite city cons: "the Iron Hat, the Puff Racket, the Tat, the Silver Fox Fur--and its variant, the Cat-and-Rat Farm."

The farmers in our story are Francis Bartus and Nick Camp, Columbia freshmen from, respectively, the suburbs of Detroit and Baltimore. Francis has a Mohawk, and Nick wears a goatee. They met last fall during the college's community-service-driven orientation program, "Urban Experience." A few Saturdays ago, they set off for a walk, stopping to admire the Cathedral of St. John the Divine before continuing down Columbus Avenue. "It was a beautiful afternoon," Francis said. "A lot of people out and about."

When they reached 107th Street, Francis felt his arm collide with another arm, which was carrying a bag. "It felt like a bag of ice: heavy and lumpy," he said. The bag dropped and, from the sound of it, a glass bottle broke. The students crossed the street, looked back, and saw a man and a woman, both in hooded sweatshirts, looking at the ground, where ...