Describe the policeman on the beat in "After Twenty Years."
O. Henry does a remarkable job of introducing a major character without actually revealing who he is. The reader is deliberately misled into taking the cop for just one of many uniformed cops patrolling a beat in New York City. The cop (who we later realize is Jimmy Wells) also deceives Bob, who mistakes him for the cop assigned to this particular beat and thinks he is only stopping to talk to him because he looks as little suspicious standing in a darkened doorway. Bob doesn't give Jimmy a chance to identify himself but starts in doing all the talking.
“It's all right, officer,” he said, reassuringly. “I'm just waiting for a friend. It's an appointment made twenty years ago...."
Bob seems to be trying to show that he is completely innocent and at ease. He lights his cigar, both as a way of showing he feels at ease and of demonstrating that he is standing in a doorway because he can't very well light a cigar or smoke it out in the rain. When he lights the cigar he reveals that he is the man wanted by the Chicago police. So Jimmy refrains from introducing himself to his old pal and lets him do most of the talking.
O. Henry makes Jimmy seem like just another uniformed beat cop simply by describing an ordinary beat cop.
Trying doors as he went, twirling his club with many intricate and artful movements, turning now and then to cast his watchful eye adown the pacific thoroughfare, the officer, with his stalwart form and slight swagger, made a fine picture of a guardian of the peace.
The ironic thing is that Jimmy really is patrolling his own beat--which just happens to be where he plans to meet Bob at 10 p.m. He is a bit early, so he does what he always does, which is mainly trying shop doors to make sure they are securely locked. Bob pulls out his ornate pocket watch.
“Three minutes to ten,” he announced. “It was exactly ten o'clock when we parted here at the restaurant door.”
This dialogue is to inform the reader that Jimmy is early, which explains why he was trying doors along the way and taking his time about getting to the rendezvous. It also informs the reader that the appointment is for ten o'clock. If Bob says he will wait a half-hour longer than that for his friend to arrive, then Jimmy knows he has until ten-thirty to get someone to make the arrest which he doesn't care to make himself.
Incidentally, the "handsome watch" with the lids set in small diamonds is one of the things by which Jimmy identifies Bob as the man wanted by the Chicago police. They sent a "wire," a telegram, in which they provided as much of a description of 'Silky' Bob as possible. Photos or even sketches could not be sent by wire. They also included two other things Jimmy saw when Bob lit his cigar.
The light showed a pale, square-jawed face with keen eyes, and a little white scar near his right eyebrow. His scarf pin was a large diamond, oddly set.
The setting for the large diamond would have been described in more detail in the telegram. Since Bob never gives his name, O. Henry would have to provide other means by which Jimmy could be sure the man in the doorway was really his old pal and really the man wanted in Chicago. Bob doesn't introduce himself by name because that would have pretty much forced the cop to do the same. And if the cop didn't introduce himself, that might have made Bob suspicious--in which case he might not have been standing there when the tall plainclothes detective showed up at around twenty minutes past ten.