An Argyle Terrace resident writes: "After I dialed the same wrong number for the third time, the nice lady on the other end suggested, 'Why don't you fine yourself each time you dial a wrong number and then contribute the proceeds to Children's Hospital?'

"Accepting her suggestion, I have been fining myself $1 for each wrong number. As you can see from the enclosed check for $11, her suggestion isn't curing me of dialing wrong numbers but it is doing some good for the hospital."

That's just one of the many interesting letters that accompany the checks you readers have been sending in for Children's Hospital. Here are a few more:

"Am hand-delivering this in the hope you will add a few words to your good advice about winter driving. In addition to clearing off all window surfaces before starting out, there is something a driver should do just after he begins to move. He should test his brakes.

"Sometimes moisture gets into braking systems. Sometimes brakes freeze. Sometimes a cylinder or master cylinder lets loose overnight. The first time the driver attempts to use his brakes he discovers he doesn't have any. He doesn't have to be going very fast for that kind of inadvertence to become a fatality that could have been avoided.

"It is always a good idea to test brakes during the first few feet of movement. If they're going to fail or lock or malfunction in any way, the time to find it out is before the car starts going very fast.

"P.S.: What do you do if your foot brake fails? You use your emergency or hand brake, of course. Every driver ought to fix that procedure in his mind before an emergency arises so that he won't have to waste time thinking about it after the emergency is upon him."

A letter that caused my electronic abacus to blink its lights a couple of times said: "During the course of 1976, we filled three beer cans with 500 pennies each, so we are sending you $25 for Children's Hospital. We have already started a new container of pennies for next Christmas. Beer cans are too hard to empty."

Gee, if I had known you were having trouble emptying those beer cans I would have been happy to send you some help. I have a couple of friends in the Sports Department who are very adept at emptying beer cans.

Incidentally, friends, good luck with your new container. I hope it continues the great tradition established by the beer cans and values 1,500 pennies at $25.

There are, alas, some very serious letters in the year-end shoebox mail. One such letter that arrived Monday had this to say:

"Last year, my son was in Children's Hospital for open heart surgery. His case called for one of the less complicated techniques. His operation was successful and he was home in eight days.

"The first four days were terribly frightening and filled with anxiety. But the care the children received was truly inspired, and those of us who spent so much time in the Intensive Care waiting room got incredible support from the staff.

"All the wonderful things we had heard about Children's Hospital turned out to be true.

"Our charges for room and board, operating room, drugs, tests, X-rays, special equipment and all the rest came to $5,800, and I'm sure that some families get far bigger bills in complicated cases. Fortunately, we had insurance that paid almost all of the costs.

"But it is reassuring to know that Children's Hospital never turns away a child whose parents find themselves in the fix having no money to pay it for them. It is so good to know that, year after year, the funds to provide by voluntary contributions from residents of the entire metropolitan area served by the hospital.

"I guess what I'm trying to say is: 'Thank you, good neighbors, for caring. Thank you for caring about children - yours and mine and everybody's."

Now that you mention it, ma'am, it is a remarkable thing that we have maintained this tradition for 105 years in a transient community where people are constantly moving in and moving out, and nobody is expected to have roots.

A check for $50 accompanied a letter that said: "Last year we wrote you in mourning. Our son had just died while undergoing open heart surgery at Children's Hospital.

"The doctors had saved him once, the day he was born. Last year, they couldn't.

"In this two years, our son brought us great joy. This year, we write to you in hope. We are expecting a child any day now. Our hope is that it will be a healthy child. But we know that if help is needed, Children's Hospital is here, and will provide us with the best there is.

"Please accept our check as a small measure of our appreciation to Children's Hospital for everything it did for our son. Perhaps this money will help some other child whose need is now."

Tomorrow we will go back to tallying the checks that go into our shoebox for Children's Hospital. We'll be all business again, and have no time for the stories that accompany those checks. But for one day we played hooky from the nuts and bolts of fund-raising, and I hope you'll forgive the digression.