When he came out of retirement at 86, composer and ragtime pianist Eubie Blake often hid his long, spidery fingers in a woolen scarf to keep them warm and limber for the inevitable visits to a nearby piano. When he got there, he would always play his two most famous songs--"Memories of You" and "I'm Just Wild About Harry"--before cutting into the infectious ragtime from his earliest years in show business. His fingers would scamper up and down the ivories, the left hand beating out a thumping and thoroughly intoxicating bass line while the right explored enchanting melody lines.

In the last years before his death Saturday at 100, he seemed at once serene and frail, but that was only the outer frame. Thin, bald and bespectacled, Blake was always tucked in a natty suit, and some hoped there was lead in his pockets to kept him from floating away as easily as one of his melodies. And yet he outlasted most of the pianos he played and he certainly never went out of tune.

When President Reagan bestowed the Medal of Freedom on Blake in October 1981, Blake seemed almost embarrassed, as if he were being rewarded for his own pleasure, not that which he'd brought to millions. "All I know how to do is play the piano," he said softly, his raspy voice choking back emotion. "You know, my mother used to say, 'You ain't ever gonna be nothing but a piano plunker.' And you know, that's what I am--a piano plunker."

Over the last decade, Eubie Blake's birthdays had become public celebrations. His most recent one, just a week ago, found him too tired to attend, but the letters and telegrams, including one from President Reagan, still came by the bushel. He had been in Washington several weeks ago for the taping of a televised tribute and centennial celebration; in recent years, Blake's health had been deteriorating; he died at his Brooklyn home on Saturday from pneumonia.

The ragtime revival of the '70s had focused new attention on Blake as a prolific composer whose most important works may have been the series of Broadway musicals written in the '20s and '30s with Noble Sissle and Andy Razaf. "Shuffle Along," which opened in Washington in 1921 before a two-year run in New York, was the first all-black show on Broadway. Many critics believe that if Blake hadn't written it, George Gershwin might never have written "Porgy and Bess."

In any case, the landmark "Shuffle Along" inspired a black presence on Broadway that has been renewed in recent years in part by the success of "Eubie," a show based on Blake's vast catalogue. His Broadway work, which included "Chocolate Dandies" and "Blackbirds of 1930," allowed performers like Josephine Baker, Paul Robeson, Ethel Waters, Florence Mills and William Grant Still to move on to greater fame. When a black roadshow of "Shuffle Along" went out, it broke down previously locked doors at many white-only theaters around the country. And a quarter-century later, a guy named Truman adopted one of its best numbers, "I'm Just Wild About Harry," as a campaign song and rode it back to the White House.

Three years ago, when the U.S. Army bestowed upon him its Distinguished Civilian Service Medal during a concert on the Capitol steps, Blake simply remembered his long USO service as "I led the band." At 97, it was a habit he apparently couldn't break: As the Army Band launched into a martial moment, Blake's bony hands swept up for a little sideline conducting and his face cracked into a gold-speckled smile.

He seemed to enjoy hearing others perform his songs--there were more than 3,000 of them--but even more, he seemed to enjoy playing them himself, which he did with a power that belied his years. The jazz writer Whitney Balliett noted several years ago that "we have come to relish Blake for his unflagging turn-of-the-century spirit and for his two-foot hands, whose fingers stroke up and down the keyboard like trireme oars." Blake's playing was often ragged but always right. On the Capitol steps, he unveiled a new composition, "The Boston Pops March," written for Arthur Fiedler, who had died before he could hear it. "I can remember one part of it," Blake said sheepishly, "but the rest will be a surprise to me when I hear it!"

The sound of surprise--and the sense of humor--were never stilled, for Blake kept working: in his nineties, when he wasn't accepting honorary degrees or appearing in concert or on television, he was still handing out business cards and setting down new songs in his Brooklyn home. "I write the melodies upstairs," he recalled, "then I come downstairs to the piano and do what I call putting the dress on the girl. I put some harmony under the melody." Someone asked him once how it felt to be 95. The answer shot back warmly: "You ought to try it sometime."

Blake's longevity was astounding. He came of age in a era before electric light bulbs and horseless carriages. As a youth, he was excited by news reports of the Spanish-American War, yet had a hard time proving he was and too old for the draft during World War I. "I'm not a fighter, I'm a composer," Blake, who was 31 when the war started, told the authorities.

By the early 1900s, the Baltimore-born Blake already had a way with a melody. He'd gotten an early start, of course: At age 6, he'd strayed from his mother in a department store, found an organ and begun to pick out tunes on it. It wouldn't be the last time people were astounded.

Years later, Blake recalled the outcome of his sortie. The salesman, he said, talked his mother into telling the family's address. "That was a Saturday night. On Monday morning they backed a truck up to our house and delivered an organ. She put a dollar down and paid 50 cents a week. That way you pay for the organ the rest of your life."

His mother, a stoutly religious woman, didn't like the syncopations her son gave to church hymns. One day, as Blake livened up a classical excercise with the infectious rhythms adapted from black funeral bands and church shouting, his mother opened the door and said, "Take that ragtime out of my house." It was the first time he'd ever heard the word for what he'd been toying with for years.

"I had six years of piano lessons," he recalled, "but I picked up ragtime by ear. I first heard it when I was about 11 or 12. It had no name. It just swung and made me feel good. It was my baby. Goodbye, Beethoven." Blake was often asked about his early start, but he tended to downplay it. "I guess I was all right, but I don't know. Mozart was better at 4."

At 15 he began to perform in one of Baltimore's fancy bawdyhouses. "I pronounced it 'body house,' " he laughed years later. "I knew what it meant and thought it was spelled that way. Sneaking out of the house I would be in short pants or knickerbockers, but on the job I was 'The Professor' and had to wear long pants. I rented them from a poolroom man for 25 cents a night. They came up to my armpits." Eventually a family friend told on him to his parents (he'd been betrayed not by sight but by sound when the friend recognized "that wobble-wobble he puts in with his left hand"). Because Blake earned decent money, he was allowed to continue in a career in music that would stretch out for another 85 years.

His first tune, "The Charleston Rag," was composed in 1899, the same year Scott Joplin wrote "Maple Leaf Rag." During the 1975 copyright revision hearings, Blake offered one of the more eloquent testimonials to the importance of raising the rates: "I've been composing since 1899, and if I had to live off my royalties, I'd be in the poorhouse tomorrow."

In fact, he'd retired from show business at 65 after a long career, only to jump into it again at 86 with the renewed interest in ragtime. In 1968, producer John Hammond took Blake into Columbia Records' fabled recording studio in a church. Blake reportedly tried a half-dozen pianos without satisfaction until there was only one left. Nervously, Hammond whispered to an aide, "All right, go get the key to Vladimir Horowitz's piano." Hammond's nervousness proved out when Blake's strong attack broke one of the strings. "Thank God Horowitz isn't here!" he whispered.

After the release of "Eighty-Six Years of Eubie Blake," the composer became familiar in a way he had never been in his prime. He gave concerts, appeared on talk shows, recalled the old days and the new days with equal warmth. He had had one "vice"--he'd smoked a pack of cigarettes a day since age 6. "If I'd known I was going to live this long, I'd have taken better care of myself," he once said. But on his 97th birthday, Blake seemed decades younger. "I don't drink," he said. "And I'm too old for women anymore. They don't want me, I want them." The glint was in his eye still.

Eubie Blake was asked once what his "secret" was. "It's no secret," he replied gently. "God--or somebody up there--says it out loud all the time: 'Be grateful for help. Be grateful for luck. Pay the thunder no mind--listen to the birds. And don't hate nobody.' "

And there were the words that Eubie Blake often spoke at the end of a lovely song that could just as well serve as the period at the end of a well-spent life. "And that's it." That was enough.