It started so simply. Kate Van Winkle Keller was just looking for music for her daughters to play in their fife-and-drum corps's bicentennial program. But before she was finished, she had cataloged all the hit tunes of the 18th century in a computer data bank.
It's not just that she's a very helpful mother. She happened to discover a book of fife tunes collected in 1762 by a Connecticut country boy named Giles Gibbs that no one knew existed. (That was probably because it had been filed under his name, not under ''fife.'')
At first she kept track of it and other finds on color-coded index cards in a shoe box. But now, if you can name that 18th-century tune, The National Tune Index, a computerized listing of everything she found, will show you how to hum it, how many other versions there were, and where they all are.
Mrs. Keller got a grant from the Connecticut Historical Society to do more research on the Gibbs manuscript and began to turn up a wealth of old music.
''The first thing I found was military material. I found fife books, I found drum books. Not only printed manuscripts. Americans keeping track of their own tunes!'' she says, the excitement of the hunt lighting up her eyes and bringing color to her cheeks as she chats between lectures at a Dance History Scholars Conference at Harvard. ''Then I found, in the fife books, dance instructions.''
She also saw how tunes got variations tacked on and the titles changed, but figured they could be tracked through the century. To cross index, she began another shoe box.
When her husband, Bob, a nuclear engineer for the Navy, saw her ''A'' shoe box and her ''B'' shoe box, he suggested she try putting the information on a computer.
Thanks to new ''user friendly'' home computers and her own friendly attitude toward new ideas, this was not the awesome technological feat it might seem. Mrs. Keller translated ''do, re, mi'' into ''1, 2, 3'' (up to ''7'' for ''ti''), because numbers work better than words in a computer and because this allowed her to map the ''shape'' of a tune better -- to know how it sounded, no matter what key it was in. Now encoding tunes has become habit. Mrs. Keller will merrily break out in a melodious stream of numbers to prove it.
She and Carolyn Rabson, a musicologist from Clarkson College in Potsdam, N.Y. , proposed to the National Endowment for the Humanities that they catalog 60,000 secular British and American tunes of the 18th century. The endowment and the Sonneck Society, a society for the encouragement of music in America, funded them for $38,500.
Mrs. Rabson and her husband, a math professor who wanted to know more about computers, and Mrs. Keller and her husband all went to work. The Rabsons used Clarkson College's computer system, while the Kellers batted out tunes on their home computer. After three years they had a data bank making it possible to find out how many versions of ''Greensleeves'' there were in the 18th century, how they changed, and where to find them.
This kind of information is not meant for the general public. But it will help scholars find manuscripts in moments, saving them the time it usually takes to write to various libraries and collections asking for what they want. It is now easier to see what people liked in the 18th century, which Mrs. Keller hopes will shatter some illusions.
Life then was more fun than we have been led to believe, she discovered. She found dance instructions that belonged to a Yankee preacher, proving that the Puritans did dance. And the Puritans loved music so much they sent back to the old country for copies of the latest numbers. Also, the music didn't spring spontaneously to people's lips. Many tunes that were hoed down to in barns and taverns were borrowed from sources like Handel and Purcell.
''Most of the material which is now folk material was composed -- of course it was composed!'' she says. ''The folk don't sit down and write melodies and have the kind of stuff that really lasts. No, they work on it. They work on good melodies and make 'em folk, which lasts better. Sometimes the good melodies are too good. They're challenging to the mind. The folk will work them over, tear them down, and make them memorable. That's the folk process,'' now mapped out in the Tune Index.
Equipped with a BA in music from Vassar and a career as a mother who sang semiprofessionally, Mrs. Keller had to invent her own process to ferret out the information she needed.
She learned the researcher's cunning as well as how to talk to experts without being intimidated. About library deportment she says, ''You learn that you never go anywhere with a pen (so as not to alarm librarians with the possibility of 20th-century ink stains on 200-year old sheet music). For help in research, she ''went to the top,'' which meant talking to eminent musicologists and historians. She researched what she needed to know and what they had published, and then asked questions.
Mrs. Keller says she's happy she chose ''the route of home and motherhood,'' even though she now finds herself surrounded by PhD's. ''I do not have the academic credentials that some people feel you need. But I feel that I have something else in my performance training. I can put across to an audience what I'm trying to do in my work. As a volunteer with the Girl Scouts, I know how to teach anything from fire-building to how to code 18th-century manuscripts.''
The National Tune Index to 18th Century Secular Music is available on 78 microfiche with a printed User's Guide from University Music Editions in New York. The price is $350.m