Replies and ripostes to recent columns . . . .

PATIENTS WHO "STIFF" DOCTORS: I published the bleats of a Northern Virginia internist whose patients often fail to pay him promptly. He's so fed up that he's thinking of hiring a collection agency. For no particular reason (except that he happened to tell me), I noted that the doctor earns more than $100,000 a year. Perhaps unsurprisingly, the six-figure income attracted far more reader reaction than the question of patients who don't pay.

"Maybe he should trade in his Rolls, get a cheaper car like a BMW or a Porsche and move into a cheaper half-million dollar house," suggested George Benns of Silver Spring.

"I had to get out a large towel to cry in as hankies would not be large enough. It just broke my heart," added Leah Guss, also of Silver Spring.

All right, all right, the guy makes a lot of money, relatively speaking. But does that mean he isn't entitled to collect what he has coming? I say no. I say that any medical bill that isn't caused by an emergency (and that's most of them) should be paid as promptly and as fully as any other.

This isn't the first doctor to make a good living. But he does have at least some claim to big bucks. He was highly trained for many years, don't forget. And once in a while, some docs do save lives (even if many docs don't save anything more critical than sagging necks and drooping psyches).

If you're looking for prevention rather than cure, a reader who requests anonymity has a good idea.

"Maybe this doctor should put into effect the same practice that my regular GP started approximately five years ago," the reader writes. "When you visit the office, you pay at the desk upon leaving. And this is posted in the office in several places so it cannot be missed."

20TH AND K, RATHER THAN K AND 20TH: Why do we Washingtonians always say it that way? I couldn't come up with anything better than a guess. But Wayne Millan, a graduate assistant in classics at the University of Maryland, has a scholarly opinion that sounds euphonious to me.

"What is involved here is metrics, a thing we classics students worry about a lot," Wayne writes. " '20th and L' has two hard beats to it: an initial beat on the first syllable of '20' and a second hard beat on 'L' . . . . 'L and 20th,' on the other hand, has two weak syllables ('ti-' and '-eth') trailing off at the end, and this does not sound particularly poetic to us."

THE REAL JOB OF THE PARK POLICE: In a recent column, I jousted by phone with a reader who couldn't understand why the Park Police don't sweep all those scuzzy demonstrators out of Lafayette Park each night. Because demonstrators have rights too, I argued, and rights don't depend on how often you bathe. Besides, I said, the Park Police aren't there to censor political opinions. My reader wasn't persuaded.

"A Police Officer's Wife" was unpersuaded by something else: My reader's implication that cops enjoy protecting people who smell like last month. Park Police officers "would like nothing more than to remove those nasty people from Lafayette Park," the wife writes. "But as you noted, everyone has rights."

Amen. And thank heavens the Park Police do such a consistently good job of remembering that.

EELSKIN WALLETS THAT ZAP FARECARDS: Back in March, I reported that eelskin wallets had stripped the magnetic coding off of several Metrorail Farecards. Subway officials were mystified. Gift shop owners were mystified. If I'd been able to reach any eels, they probably would have been mystified too.

Shirley Heft of Kensington wasn't. Turns out the answer has nothing to do with eels and everything to do with clasps.

"Most eelskin wallets are designed, not with a snap closure, but with a magnetic closure," Shirley writes. It's well known that anything magnetic can send a Farecard's coding to Oblivionsville. End of mystery. Thanks to Shirley.

KIDS, PARENTS AND GROCERY-STORE CANDY: In another March column, I mentioned that Giant Food stores removed candy displays from certain checkout lines because parents (and I suspect Giant too) had gotten sick of kids who whine and shriek and beg for a treat.

Ann M. Kane of Fort Washington says that rather than praising Giant, I should have tongue-lashed weakwilled parents.

"I fail to see why Giant Food or any other store should remove candy from a prominent place simply because Mom and Dad can't or won't say NO to the kids," Ann writes. "What ever happened to disciplining the children? Or am I being too old-fashioned?"

No, Ann, you're not. You do overlook the fact that whining and shrieking becomes public when it takes place in the Giant. Therefore, it's more than a question of one parent disciplining one child. Innocent eardrums are at stake. Still, Ann, you're right on the button in general. A parent who can't say no is a parent who's heading for trouble.