Many is the time I have passed an embassy, in this capital full of them, only to spot two federal policemen standing in front of it, bored to tears.

A classic Washington waste of money and time, I'd say to myself.

Look at those jokers -- nodding at visa-seekers, getting paid for learning how to say thank you in Swahili. Why not send them out to chase thieves?

But then I'd tell myself: Better not.

No doubt these cats are so used to playing cigar-store Indian that, if a real-life crime were ever committed, they wouldn't have the slightest idea of what to do.

Well, William Brown has buried that illusion once and for all.

Brown is a motorscooter patrolman for the uniformed division of the U.S. Secret Service (that's the new, fancy-pants name for the former Executive Protective Service).

Last Thursday, he turned in as good a piece of police work as I've seen.

The scene was lunch hour, at Vermont Avenue and L Street, NW. I had just left a Chinese restaurant, and was cursing myself for the three millionth time for using too much Chinese mustard, when the sidewalk suddenly turned into a football game.

Here came a young man, running along L Street, past a construction site, directly at me. Hot on his heels was a man who later identified himself as Nicholas Gaeta, 67.

At the same time, at the far end of the block, a man in a buckskin jacket was shouting to officer Brown, who happened to be motorscooting past: "Police, police! That way!"

Now, you should understand Brown's legal situation. He did not have to do what Mr. Buckskin asked him to do because his jurisdiction does not include public streets. On L Street, Brown was allowed to make a citizen's arrest, but so was anyone else.

Brown could have said, "Tough luck. I'm not a Metropolitan policeman. Better call one of them."

He could have made an excuse, like, "Sorry, I'm on a special mission to ride shotgun for Ambassador Hotshot."

More likely, he might have frozen up with indecision for a few seconds, allowing the young man time to escape.

But Brown immediately tore off after the young man. He caught up halfway down Vermont Avenue, jumped off his scooter and ordered the suspect to halt.

Then, holding the suspect with one hand, Brown radioed for help with the other. In less than a minute, six policemen were bundling Harry Spencer, 19, off to jail.

The charge: stealing a wallet out of a purse that a woman had left unguarded in an office a block away.

But Brown's arrest was only part of the tale. Even though he was weaving in and out of traffic at the time, Brown had seen the suspect throw the wallet down into the construction site.

Brown got a hardhat to lob the wallet back up to him -- money still inside -- just as its owner came huffing up to the scene.

As he returned it to her, she said thank you.

In a rare Western tongue known as Grateful English.

Maryland's Charles Mathias is hardly the only U.S. Senator guilty of inserting drivel into The Congressional Record. Still, he lit up my manure-meter with an item that appeared under his name on Sept. 12.

It's an ode to Baltimore, in honor of The Port City's 250th birthday. But it reads like a Palm Beach Chamber of Commerce travel brochure.

"It is not easy to capture in words the special qualities that make Baltimore the magnificent and richly varied city it is," Mathias actually said, on the floor of the greatest legislative body in the world.

Well, Mac, it ain't hard, either.

Crushing air pollution, the notorious dives along "The Block," the world's most dangerous tunnel and the world's most grating accent.

Mathias added that Baltimore "occupies a very special place in the esteem and affection of all Marylanders."

Namely, a low place. As most Marylanders know only too well, former governors Spiro Agnew and Marvin Mandel weren't born and reared elsewhere.

Mathias finished by inserting into the record a gushy 2,500-word editorial that appeared in The Baltimore Sun of Aug. 8.

He forgot to mention that The Sun has never seen fit to endorse any of his opponents.

To print Mathias' remarks and The Sun's editorial took up almost one and one-third pages in the Record.

According to the Government Printing Office, the tab to the taxpayers for that much type was $515.11.

Stop the presses: Catch-22 has invaded the University of the District of Columbia.

Bill Carter, who lives in the District, whose residents UDC is supposed to serve exclusively, called the college's admissions office the other day to ask them to send him a course catalog.

They said they don't mail catalogs to D.C. residents.