Accidental Heroes of the 20th Century; 32: Louis Armstrong, Jazz Genius

IF LOUIS Armstrong had not become the undisputed king of jazz, he would have made a world-class trainspotter. He was an assiduous collector of stuff, returning home from his tours laden with clippings, music scores, concert bills and tapes, which he hoarded in boxes at his New York home.

Much of the material is now open to public scrutiny in the Louis Armstrong Archive at New York's City University, and reveals him to be the same joyous, life-enhancing entertainer off stage as he was in performance. The tapes, around 650 of them, each more than four hours long, were recorded on equipment Armstrong carried around the world with him in custom- made trunks "like a 1950s Walkman", according to the archive's director Michael Cogswell.

This improvised technology that Satchmo used to record everything from hotel-room trumpet solos to his thoughts on contemporary events is significant. In all things Armstrong was an innovator, embracing the new with enthusiasm. He owned one of the very first movie cameras in the 1930s, and travelled with a typewriter from as early as 1922. Among his many tape recorders was a very early cassette deck.

The enduring image of Louis Armstrong, wreathed in smiles before another raspy-voiced chorus of some popular song like "Hello Dolly!" or "Mack the Knife", comes from his later years and clearly only tells a small part of his story.

Armstrong was more than just a popular entertainer with a horn and a white handkerchief. He was one of music's true revolutionaries. His improvisational verve and technical virtuosity virtually defined jazz in the 1920s. So profound, so indisputable was Armstrong's contribution to the developing art form of jazz that Dizzy Gillespie, the trumpet giant of the later be-bop generation, said quite simply, "No him, no me."

The background from which Armstrong emerged to place his unique stamp on American popular music makes his achievement doubly heroic. His mother, the grand-daughter of slaves, raised him in the early years of the century unassisted, a visible father being something of a rarity in the notorious Storyville district of New Orleans.

The fact that he first picked up a cornet at the age of 13 to play alongside fellow inmates in New Orleans' Coloured Waifs' Home gives a clue to the nature of his upbringing.

Not that Satchmo was some mistreated, eager-to-please pup ready to do tricks for his masters. In a grainy ancient photograph from the Jones Home for Coloured Waifs, now on display at the Smithsonian's National Portrait Gallery in Washington, Armstrong displays an unmistakable cockiness and hauteur not seen in the faces of the other young band members.

He knew he had a special gift, and if he was in any doubt, the reaction of audiences in Chicago where Armstrong performed with King Oliver's band in the mid-Twenties would have convinced him. Armstrong's purity of tone, dazzling speed, daring breaks, rhythmic drive and startling imagination were unprecedented and, to some extent, remain unequalled. "You can't play anything on a horn that Louis hasn't played," Miles Davis once said.

Armstrong continued performing after being taken ill in 1971, refusing to cancel a gig a few months before he died. He told his doctor: "My whole life, my whole soul, my whole spirit is to blow that horn. I got to do it, doc."

The quote sounds apocryphal, but is probably not. The meticulousness with which Armstrong collected his words and music - only apparent after his death - seems to indicate that his remarkable career was as much a source of joy and wonder to him as to the rest of us.