Whenever the Leveys go out of town on vacation -- which we spent a couple of weeks doing this summer -- the last thing Pop does before heading for the highway is to pay all the bills. Not just the bills that are sitting in his Action Stack. Also the bills that will come due while he's gone.

Shirley Krutilla of McLean isn't quite as compulsive. But when she and her husband took a two-month car tour of the United States and Canada during May and June, Shirley arranged with a housesitter to forward anything that looked like a bill. But the sitter neglected to forward a bill for car insurance renewal.

The days clicked by. No check from Shirley. Insurance agent Gordon Speed tried desperately to reach her, knowing that the great Nationwide computer in the sky would cancel Shirley's policy if the fee wasn't sent. But Gordon couldn't find his customer.

So he paid the renewal out of his own pocket.

"We of course reimbursed him as soon as we learned of this," Shirley writes. "But had it not been for his remarkable selfless consideration, we would have been driving uninsured for thousands of miles. Needless to say, he is a real hero to us."

The hero says he doesn't deserve that appellation.

"It's not a big deal," Gordon Speed told researcher Amy Simmons. "We've had them {as customers} for many, many years, and I didn't want the policy to lapse. We do that from time to time, if it's an emergency and they are good customers. We try to look after their best interests."

You did that and more, Gordon. And you're wrong. It is a big deal. How many insurance agents would have done the same?

We thought for a second that we had snared ourselves a fish called a Politico. But we only snared a subspecies called a Politico's Husband.

The fishing trip started on University Boulevard in Silver Spring back in June. Maggie W. Hatten of Berwyn Heights noticed a gray Chevrolet in front of her. It bore a bumper sticker that said, "MENES." Its license plate said, "MARYLAND HOUSE OF DELEGATES 48-A." The tag's expiration date said, as plain as day, "MARCH, 1987."

Maggie didn't bother to notify me at the time. But when she saw the car again on July 9 -- still with expired tags -- "I knew I had to write."

The tags belong to Pauline H. Menes, a Democrat from Prince George's County. But Pauline says the guilt belongs to her husband.

"That was my husband's car," she said. "He had them {current stickers} but forgot to put them on. I said to him that he was darn lucky he didn't get caught. If it hadn't been called to my attention, the stickers would have stayed in the envelope. He now has his little gummed sticker on his car, with a very red face."

I'm not sure the red faces ought to stop there. If the car belongs to Pauline Menes' husband, and he's not the delegate in the family, why were state plates aboard it? Is somebody bending the rules just a touch?

More than a month ago, I published a tale about a 3-year-old girl named Kelly Thompson who tried (and failed) to carry a helium balloon aboard a Piedmont Airlines flight. Then I cleverly took a business trip. Then I cleverly went on vacation.

I say "cleverly" because there wasn't much clever about the Kelly column. It may have contained more scientific misinformation than any single document since my final exam in high school chemistry 26 years ago.

Several chemists wrote to chastise me, among them Don Peterson, an associate chem professor at Gallaudet University. Helium is not combustible, noted Don (even though Bob had written that it is). Nor is nitrogen flammable (even though Bob had written that it is). Fellow chemists Corinne R. Benson of Silver Spring, Jim Willis of Annandale and Robert J. Doyle Jr. of the Naval Research Laboratory thumped me for the same errors.

As Dr. Norman H. Rubenstein of Silver Spring put it, "Otherwise, it was a very good column."

Folks, my only defense is the birds and bees.

I sat in the second row in high school chem. A young lady sat in the first. Not just any young lady. She was, as they say, a credit to her gender.

Her chemistry was a lot more interesting than any of the molecules at the front of the room. I knew I was risking a scientific career that might save the world some day. But my gaze never wavered. Passion won. Polymers lost.

Clearly, every sin comes back to bite at one time or another. This one merely took longer than most. I hereby write 100 times on the blackboard that helium and nitrogen have the properties they have always had. To coin a phrase: Chemistry is too important to be left to columnists who almost flunked it a quarter of a century ago.