From Dorothy Monroe of Northeast: "I work near Thomas Circle, and I am absolutely amazed by the prostitution I see going on near my office every day. I'm no prude, but some of what goes on would curl anybody's hair. These girls shout out their offers to men in passing cars, and their language leaves nothing to the imagination. Not to mention the way they're dressed, and how young some of them are. But I never seem to see police cars -- at least none that ever stop and make any arrests. Isn't there anything the police can do about this? I thought they promised to clean up Thomas Circle years ago."

The cops did clean up Thomas Circle years ago, Dorothy. Then they cleaned it up again. And again. And the next time they do it, they know full well that they'll have to return in a few months to do it yet again.

If it were easy to erase prostitution from the face of the earth -- or from a particular traffic circle -- the police would have done it long ago. But prostitution didn't become the world's oldest profession without reason. There's a demand for it, and therefore a supply. The police can run a "sweep" every once in a while, but that will only push the ladies and their customers a few blocks away. Both species of bird will come seeping back before you know it.

The best medicine against prostitution, I've always thought, is to prosecute the customers as vigorously as the suppliers. If a guy "trolling" Thomas Circle is aware that he stands to be arrested, prosecuted and perhaps publicly humiliated for picking up a hooker, he might think twice about doing it.

This method has worked fairly well in other cities, but it has never been given a serious, thorough try here. If we really want to "reclaim" Thomas Circle, Dorothy, I'd say this is the way.

From "A Concerned Father" in Springfield: "My son attends a junior high school about half a mile from our home. He often walks home after school with several of his friends. The other day, my son and three other boys were walking along a street near the school when a car pulled alongside. The driver was unshaven, wearing sunglasses and looked generally creepy. Very quickly, too quickly to see for sure what it was, he flashed a badge at the boys. He said he was a Fairfax County police officer and ordered them into the car. They refused. He told them, 'I'll get you for this,' and zoomed away. The boys are frightened, of course. So am I. Anything I can do?"

Three things, Dad: 1) Call the real Fairfax County police as soon as possible, and give them a full description of this character, who sounds to me like a phony cop if ever there was one. 2) Tell officials at your son's school to warn other students about the man. 3) Thank your lucky stars that your son and his friends know how to say no to strangers.

From Wilhelmenia J. Davis of Northeast: "The street light in front of my house went out on 10/20/85. I started calling Pepco on 10/21/85 and I had to continue to call every day . . . . The lights were turned on on 10/28/85 when I looked out at 5 a.m. My question concerns policy. I think one week is pretty long to wait for a light to be repaired. Does the neighborhood influence how soon Pepco responds to a problem with street lights?"

Pepco says no, no, a thousand times no, Wilhelmenia. Sylvia Nistle, a Pepco media representative, looked into the situation on your street. She discovered that the light was fixed five days after you filed the first report. On four of those five days, however, it rained, and according to union contracts, Pepco repair personnel do not have to fix lights in the rain, since that's an excellent way to fry. In general, says Sylvia, "We don't prioritize complaints. It's first-come, first served," as long as there are no emergencies anywhere. Those always get handled first. Otherwise, says Sylvia, "the neighborhood doesn't matter. Service is provided to all people, regardless of where they live."

From Gerry Martinson of Northwest: "I'm so mad I can't see straight. I went into a downtown drug store the other day. Big chain. One of the biggest. Place was jumping with people. No way the cash registers aren't as full as can be. I buy a 25-cent pack of Life Savers and hand the cashier a $5 bill. She says, 'Have you got something smaller?' What kind of nonsense is that? If a big drug store can't change a $5 bill, it ought to go out of business."

The question would have boiled my blood, too, Gerry. But let's aim our brickbats at the proper target: store management, not a clerk who's just doing what she's been told. The real silliness here is the notion that a cash register line moves appreciably faster if a clerk handles the smallest bills possible. Take your Life Savers situation. The only difference between paying for them with a $1 bill and paying for them with a five is the time it takes the clerk to find four ones. That might be two seconds; three on a bad day. Is that significant enough for a store to make a permanent enemy?

One for the ages out at Tysons Corner the other day.

Everybody and his brother is there to Christmas-shop. Which means everybody is trying to find a place to park.

In one corner of the parking lot, a man starts to pull out of a space. A Toyota approaches from one direction to claim it. A Cadillac, hoping to do the same, approaches from the other direction.

As soon as the space is vacant, the Toyota scoots right into it. The Toyota driver rolls down the window and calls to the Cadillac driver, "It's nice to be fast!"

Without hesitating for a second, the Cadillac owner slips her car into gear and rams the Toyota's rear bumper with considerable force. The Toyota driver leaps out, rushes up to the driver's window of the Cadillac and screams, "What do you think you're doing?"

The Cadillac owner rolls down her window and replies, cool as can be:

"It's nice to be rich." CHILDREN'S HOSPITAL

Good news for Mother Goose & Grimm fans. Because of popular interest, that comic strip returns to the paper this morning.

Meanwhile, Middle Ages is being discontinued by its syndicate. Mark Trail and Luann will return in late January, as previously announced.

The biggest problem for returning overseas travelers is not jet lag, not catching up on the newspapers and not facing the boss again.

It's coins.

What the heck do you do with all those guilders, shillings, francs and what-have-yous that always seem to fill your pocket or purse?

No U.S. bank will exchange them. No U.S. business will honor them. No child will believe that the Tooth Fairy has decided not to use American money any more. The long and the short of it is that you're stuck.

But for the third year in a row, Ruesch International is here to unstick us.

Ruesch is a foreign exchange brokerage at 1140 19th St. NW. If you walk in there with your foreign coins, Ruesch will convert them into American money and give all the proceeds to our fund-raising campaign on behalf of Children's Hospital. There's no charge to you, and no fee to the hospital.

It's a terrific program, and a terrific way for Children's to profit from money that would otherwise sit in a drawer. If you've been wondering what to do with all those strange coins you brought home with you, wonder no more.

TO CONTRIBUTE TO THE CAMPAIGN:

Make a check or money order payable to Children's Hospital and mail it to Bob Levey, The Washington Post, Washington, D.C., 20071.