Chris Rueff, a lanky 30-year-old Californian, carefully sorted through the equipment he needs for his work: a guitar, an American passport, two harmonicas plus neckbrace, a small tin for collecting money, a bracelet for his biceps, and a "carte orange," entitling him to a month's limitless rides on the Paris Me'tro.

"Bonne chance!" (good luck), shouted Jean-Luc, proprietor of a cafe' near the Cha telet Me'tro station patronized by the growing army of street musicians in Paris. It was 9 a.m. A haze of heat and pollution hung over the River Seine, and the rush hour was petering out. The ideal time to start working the Me'tro.

Over the next hour, Rueff made 100 francs--around $12.50--riding subway cars from Cha telet to the Champs Elyse'es and entertaining fellow travelers with a mixture of rock and blues. Within three hours, his pockets were weighed down with 10- and 20-centime pieces. Hoarse from singing above the roar of the Me'tro, he emerged blinking into the sunlight.

The Paris Me'tro is a street musician's paradise. Its 130 miles of track and 358 stations provide good and not-so-good musicians from all over the world with a captive daily audience of some 2 million people, each of whom spends an average of roughly 40 minutes a day riding the subway.

In theory, it's illegal to perform in the Me'tro. There's a sign drawing attention to the fact in every wagon and, as likely as not, a singer belting away at his guitar right underneath.

What makes the Paris Me'tro unique is not just the number of musicians, but their imagination and ubiquity as well. On other subways, the performers generally restrict themselves to playing music in the corridors. In Paris, they jump onto the trains and provide almost every conceivable type of entertainment--from classical music to puppet shows to a four-member steel band.

The regulars were recently joined by a drunk who handed his hat around after an impassioned denunciation of France's Socialist government. He seemed to make quite a lot of money from the amused travelers.

The Cha telet station is at the center of the Paris street musicians "scene," according to Rueff. Close to the capital's historic core, it lies at the hub of four separate subway lines. The entertainers' favorite is the one that leads to the Champs Elyse'es via the tourist attractions of the Louvre, the Tuileries and the Place de la Concorde.

Rueff knows all the station regulars: the undercover policemen, the guards, the pickpockets, the cleaning staff and, of course, the other performers. The musicians come from all over the world, including a refugee from Soviet Georgia who plays with an Israeli. The largest contingent are the Argentinians, who produce their own Spanish-language magazine called The Voice of the Voices of Cha telet.

"A lot of the guys around here treat this like a 9-to-5 job with a break for lunch," said Rueff. "They have to earn enough money to support their wife and five kids. For them, it's entirely uncreative. Many of them have been singing the same song for the past six months."

Rueff, who is a bachelor, writes his own songs--timing them to last exactly one Me'tro stop. He regards each ride to Champs Elyse'es and back as a separate performance in which he entertains his fellow travelers with a mixture of swing, rock music and blues. On the last two stops, still playing his harmonica, he "bottles"--the term used by street musicians for collecting money.

On a good day, Rueff can get the whole carriage stomping feet and applauding in time with the music. On a bad one, he has to contend with hecklers telling him to go home to America.

"I try to make contact with people by looking them in the eye. Watch how people behave in the Me'tro. It's as if they were in a state of depression. They're starving for people to look at. They send out signals. If you can shoot the signals back, you've got a whole thing going," he said. Paris street musicians, Rueff said, tend to avoid the first-class cars in the middle of the trains. "People who travel first class are snooty, act as if 'hey man, we've got our own life to lead' and bury themselves in their newspapers." The only time Rueff ever sings in first class is during the rush hour, when the second class is so packed that bottling becomes impossible.

Rueff said that the worst 'tippers'--another street musicians' expression--are American tourists, who also have the loudest voices. The best are ordinary Parisians who seem to have developed a taste for music in the Me'tro.

At times, the me'tier can be hazardous. When Rueff first came to Paris 10 years ago, he was promptly arrested the first time he tried singing in the Me'tro and spent a night in a police cell. He has also been involved in fights with English competitors over the right to sing outside movie theaters along the Champs Elyse'es. Last summer he injured his vocal cords from too much singing.

Many street musicians keep going in the hope that one day they will be "discovered." Legend has it that Sugar Blue, one of the harmonica players for the Rolling Stones, started out on the Paris Me'tro. So, too, did a number of now prominent classical musicians who worked station corridors when they were students at the Paris Conservatoire.

"I think I've taken this gig about as far as I can," said Rueff, who started out as a male stripper in Denver and has sung on street corners all over Europe and North America. "I love it, but I want to move on."

His hopes that one day he will make it are expressed in the song he wrote himself:

Do you see my train?

Does it bear my name?

Can you touch my train?

Will it feel my pain?

I say, my train.