SPRING COMES hard down here.

The switchman was in the lotus position -- serenely posed on an army blanket he had neatly folded into quarters before he assembled his tools and took up his post for the day. A black man with glowing bronze skin, hair falling straight and glossy down either side of his head like a helmet, framing a face that was mostly skull.

He held a thick pad of graph paper open on his lap, carefully filling a page with finely shaded symbols -- a covert calligraphy all his own. He didn't bother to hide his work from passing citizens. His half-smile said it all -- the simple slugs thought him insane; they could never understand the difference between the messenger and the message.

A pale-blue quilt covered his shoulders. He placed three identical blue china bowls on the blanket around him. To his right, the bowl sported a generous supply of fine-point felt-tip pens in different colors. The bowl on his left held a heavy Zippo cigarette lighter and some loose cigarettes -- various brands. Directly in front was a bowl with some coins, encouraging the passing citizens to make a contribution to his mystical cause.

He had long tapering fingers, clean and smooth, the nails manicured and covered with clear polish. I got a good look at his hands yesterday when I stopped to look over his shoulder and watch him work. He filled a quarter of the page with symbols, never using the same one twice, working in five separate colors, not acknowledging my presence. I helped myself to one of his cigarettes, lit it with his lighter. He never moved. I tossed some coins into his china bowl and moved on, smoking his cigarette. It tasted like it was about my age.

I didn't need the polished nails to tell me he was the switchman. The neighborhood is full of halfway houses for discharged mental patients -- they disgorge their cargo into the streets each morning, but this guy wasn't part of that herd. He wasn't talking to himself and he hadn't tried to tell me his story. And he didn't look afraid.

The little piece of winter chill still hanging around in April didn't seem to bother him. He worked the same post every day -- starting around eleven in the morning and staying on the job until about three. The switchman had a choice spot, always setting up his shop at the edge of a tiny triangle of dirt on West Broadway, between Reade and Chambers. The slab of dirt had a couple of broken backless benches and a runty tree that had been bonsai'ed by years of attention from pigeons, dogs, squirrels, and winos. An alley without walls. Down in this part of the city, they call it a park.

At eleven, he would still be in shadow, but the sun would make its move from the East River over to the Hudson past noon, and things would warm up. The switchman never took the quilt from his shoulders.

His patch of dirt was a border town: Wall Street was expanding its way up from the tip of Manhattan, on a collision course with the loft-dwelling yuppies from SoHo. Every square inch of space was worth something to somebody -- and more to somebody else a few months later. The small factories were all being converted into co-ops. Even the river was disappearing as land-greed took builders farther and farther offshore; Battery Park City was spreading its branches into the void left when they tore down the overpass for the West Side Highway. Riverfront joints surrendered to nouvelle-cuisine bistros. The electronics stores that would sell you what you needed to build your own ham radio or tap your neighbor's phone gave way to sushi bars. Antique shops and storefront-sized art galleries shouldered in next to places that would sell you some vitamins or rent you a videotape.

People have always lived down here. The neighborhood used to be a goddamned art colony -- it produced more pottery than the whole Navajo nation. The hippies and the artists thought the winos added just the right touch of realism to their lives. But the new occupants are the kind who get preorgasmic when you whisper "investment banking," and they didn't much care for local color. Locksmiths were riding the crest of a growth industry.

The Superior Hotel entrance was around the corner on Chambers Street, with rooms extending all along West Broadway. Mine was on the top floor, facing out over the park. Seventy-five bucks a week bought me a swaybacked single bed on an iron frame, a ratty old easy chair worn down to the cotton padding on the arms, and a metal closet standing against the wall. The room was painted in some neutral-colored stuff that was about half disinfectant. A heavy length of vinyl-wrapped chain stood against the wall, anchored at one end to U-bolts driven into the floor. The other end stood open, padlocked to nothing, waiting patiently. I hadn't gone for the optional TV at only two bucks a day.

Someone who had never lived in one might say the room looked like a prison cell. It didn't come close.

Almost one in the afternoon. Into my third hour of watching, I shifted position in the chair, scanning the street with the wide-angle binoculars, watching the human traffic flow around the switchman. A young woman strolled by with her boyfriend. Her hair was dyed four different colors, standing up in stiff spikes, stabbing the air every time she moved her head. Her hand was in the back pocket of her boyfriend's jeans. He looked straight ahead, not saying a word. A biker rolled up to a tobacco-colored Mercedes parked at the corner. The car's window slid down and the biker put his head and hands inside. He wasn't there long. The Mercedes and the biker went their separate ways. A young woman about the same age as the one with the spiked hair tapped her business-length heel impatiently on the curb, holding a leather briefcase that doubled as a purse, wearing a pin-striped skirt and jacket over a white blouse with a dark-red bow for a tie. Winos stretched out in the sun, sprawled across the benches -- passengers on a cruise ship in permanent drydock. A diesel dyke cruised into view, her arm braced around the neck of a slender, long-haired girl, her bicep flexed to display a bold tattoo. I was too far away to read it, but I knew what it said: hard to the core.

Still no sign of the target. I had followed him for three weeks straight, charting every step of his lunchtime route. The calligrapher on the blanket had to be the switchman -- it was the only stop the target always made. I rotated my head gently on the column of my neck, working out the stiffness, keeping my eyes on the street. Invisible inside the shadows of my room, I lit another cigarette, cupping the wooden match to hide the flare, and went back to waiting. It's what I do best.