After you conduct an annual fundraising campaign for a couple of years, you become a self-appointed expert on fund-raising campaigns. You can guess how much will come in before your Jan. 31 deadline, and you can interpret the significance of every last-minute gurgle in the mail pipeline.

Or at least you think you can.

I thought only one large gift, the Bell System's, remained in this year's pipeline. To learn how wrong I was, read on:

Junior Girl Scout Troop 2419 earned $4.41 for Children's Hospital by singing Christmas carols. Lt. William H. Corkrean Jr. Auxiliary 226 of the Catholic War Veterans sent me $10, and another $10 arrived from Arlington with the explanation it had been "cut cut of the pots in our family poker game."

tTu Y Yo Enterprises, a junior achievement company sponsored by the Chantilly Jaycees, manufactures and sells automobile trouble lights. It president wrote, "We are learning how difficult it is to make a profit and how many problems are encountered in the business world. We are also realizing that business has an obligation to the community that supports it. Therefore our board of directors (28 high school students between the ages of 14 and 17) voted unanimously to send you $20."

A check for $25 arrived from the Targets Division of the Air Force Intellgence Service. Children's Hospital won the $25 football pool at the Westchester Park Apartments in College Park although it wasn't even entered in the pool. The hospital's share of the money raised for many charities at Randolph-Macon Academy in Front Royal also was $25. And today's fourth $25 contribution was from "the Military Order of the Cootie of the U.S., All-Fouled-Up Auxiliary No. 5."

Patrons of The Happy Hamburger in Indian Head dropped $29.15 into a Children's Hospital jar displayed near the cash register there. The volunteer aluminum can recycling project at the Department of Justice sent me $50.

Lorton Post 162 of the American Legion gave its Ladies Auxiliary some money to put on a Christmas party. The Auxiliary spent $52.45 less than it had been given -- and I'm sure I don't have to tell you how that bookkeeping problem was resolved.

Children at the Damascus Dance Center gave children at the hospital a $28 Chirstmas present. Customers and employees of the Springfield Drug Center chipped in $69. The Procurement Operations Division of the Office of the Secretary of Transportation got up a kitty of $105. No in-house card exchange among employees of Leiss Art Services diverted $119 to the children.

You don't have to explain to the Arlington Fire Department that Children's Hospital serves the entire metropolitan area. The fire fighters are with us again this year, this time with a $140 attack on the deficit. The decision not to exchange intramural cards was worth $156 in the Dairy Division of the Agricultural Marketing Service. For the Telecommunications Department of the Navy Regional Data Automation Center, this was the sixth consecutive year of not exchanging cards, and $194 was raised.

Contributions from the Center for Naval Analyses, an affiliate of the University of Rochester, have always been generous. Last year's total was $417. This year's weighed in at $660. The analysts described the extra $243 as "an increase of 58.2733812949 percent -- approximately."

I thought $660 was going to be tops for the day, but then my telephone rang. "You ought to drop by One Flight Up," a man said. "They have some money for you for Children's Hospital. Do you make pickups?"

"Not for amounts of less than 35 cents," I said. "What's the address?"

"You go out Wisconsin, past Sears -- 4934 Wisconsin. You walk up one flight and it's known as..."

"I know. It's known as One Flight Up. How'd they collect the money -- a Children's Hospital jar near the cash register?"

"No," was the reply. "On Fridays and Saturdays they decided that nobody could get in unless he or she paid $1 for Children's Hospital."

"I'll be out tonight," I said. This had to be good for a couple of hundred dollars, right?

Wrong. I came away with a cashier's check for $12,425. So help me. Except for Navy and Bell System gifts, this was the loudest gurgle I have ever heard in the pipeline.

It pushed today's group gift tally to $14,202.01, and 51 unnamed individuals added $1,283 to make today's unexpected gurgle $15,485.01. Having begun the day with $163,204.99, the shoebox now holds $178,690. To hit $200,000, we need $21,310 by Wednesday.