Letters from just 30 District Liners arrived this morning. I'd be unhappy right now if I didn't know the mysterious ways of the mail pipeline. Last year we experienced a similar "valley" and I thought our free care fund-raiser was finished.

Then, a last-minute surge of generosity from area citizens boosted our 1979-80 campaign to a record-breaking total of just over $231,000. It's that eleventh hour rescue that I'm already looking forward to this year.

Strangely enough, just when local support seems to be dropping off momentarily, I received three letters from far outside the usual circulation zones of The Washington Post.

One letter, containing a telephone bill refund of $12.17, was sent from England with instructions to "cash the C&P refund check and use it for the Children's fund." Another check, for $75, also came from England. The third letter, with a check for $100, contained this message.

"Now that we are spending this year on a government project overseas it would be easy to forget Children's back home. However, I chanced upon a copy of the Post, saw your column and remembered your annual campaigns for the hospital.

"I am, therefore, sending this check to you, knowing it will reach the proper hands."

It will, and so will today's balance of $703.17 from the other 29 District Liners who found a place for Children's Hospital in their hearts and checkbooks. Contributions from the following area groups and businesses will also make that journey.

A check for $2.50 from Sterling Elementary School was marked simply "donation from school children." Employes of the Springfield Hechinger store won an annual storewide Christmas contest and sent in a $25 slice of the winnings. Checks totaling $28.09 were received from the Ft. Belvoir Officer's Wives Club Bowling League for Children's.

A group of Alexandria youngsters, "all 10 and under, decided to go caroling for Children's Hospital. They came home with $27.81," which was rounded off to $30. Employes of the Energy Department's Office of Energy Contingency Planning sent $60. The students of Surrattsville Elementary School collected pennies, nickels and dimes worth $63 for Children's before Christmas vacation.

"Your support in The Washington Post of Children's Hospital is wonderful," wrote employes of Transportation Federal Credit Union. "We spend so much time saving animals at the zoo, trees in the forests, buildings downtown and waterways through Georgetown; it's nice to see someone devoting so much energy to saving little human begins." They sent $80!

Members of the Office of Opinions and Review of the Federal Communications Commission collected $31 in cash and $69 in checks for a grand total of $100. Checks for $110 arrived from an adult Bible class of the College Park United Methodist Church. In the past, class members honored each other's birthdays with birthday cards, but last year they started putting quarters into a box for birthdays, and ended up with $110.

"Again this year, the teachers at Hutchison Elementary School have bought 'coupons' as the gift from their elf rather than buy a cute little gift. bThis is our third year and enclosed you will find $119 given with joy," wrote one of the teachers there.

Checks totaling $130 came from three offices of the Air Force Systems Command at Andrews AFB. Participating this year were the Directorates of Transportation, Maintenance and Supply. Sending $140 were "a few members of the National Capital Chapter Club Managers Association who elected to make the donation rather than exchange Christmas cards."

A $200 check, representing "the absence of a card exchange between the employes of The Howard Research and Development Corp. and the employes of its subsidiary, Columbia Management Inc.," made its way to may attention. oMany thanks!

So, those 13 groups added $1,087.59 to the $803.17 contributed by anonymous individuals for a daily tally of $1,890.76. Yesterday we reported a shoebox total of $135,956.43, so today we're looking at $137,847.19.

Daily totals of $2,000, while vitally important, aren't going to push us over the top. We need to do more. Please send your tax-deductible check, made payable to Children's Hospital, to: Scott Chase, c/o The Washington Post, 1150 15th St. NW, Washington, D.C. 20071.