With his concerts during the past week, Antal Dorati completed a decade as leader of the National Symphony Orchestra. For seven years he was its music director; for the past three years, he has held the title of principal guest conductor.

As the orchestra approaches its 50th anniversary season, which begins next fall, it is becoming difficult to remember the plane on which the National Symphony Orchestra operated in 1970, when Dorati led its final season in Constitution Hall, in comparison to the greatly different and improved world it now inhabits.

When Dorati took over, morale in the orchestra was at a low point, both musically and personally. Its repertoire was sadly limited. As Dorati said before his first season, "It is not hard to find masterpieces this orchestra has never played."

The orchestra's previous management had resorted to petty tyrannies of an unheard-of variety: the concertmaster, Werner Lywen, was ordered by the then manager not to walk in after the rest of the orchestra was in place onstage -- just prior to the entrance of the conductor -- as is done in every other orchestra in the world.

Instead, he was told to walk in along with the other players "just like all the rest of them," in total disregard of the fact that the concertmaster of an orchestra is not "just like the rest of them." It was a vindictive measure designed solely to make Lywen so unhappy that he would resign, since his impeccable musicianship and style made it impossible to fire him.

Unfortunately the ploy worked: Lywen resigned and moved to California just before Dorati's engagement was announced.

Dorati sensed the tensions within the orchestra as soon as he began to work with the players. He made it one of his first goals to help each musician to play his best, something he was convinced they had not been able to do previously. Among other things, this meant that, unlike some other conductors coming into a new situation, Dorati did not ask for the firing of any of the players.

Moving swiftly and positively to improve the orchestra's repertoire as well as its technical performance, Dorati introduced to National Symphony audiences no great quantity of brand-new or avant-garde music, but rather many works that had long been considered staples by orchestras to which the National Symphony liked to compare itself. s

Symphonies by Haydn and Mozart, Bruckner and Mahler, as well as less familiar works of Kodaly and Bartok, found places on NSO programs. Dorati also produced memorable evenings with the orchestra in the "Passion According to St. Luke" by Penderecki, and saw to it that the outstanding protagonists of that music, soprano Woytowicz and bass Lagger were on hand to give the new music its finest chance.

Continuing his long-standing custom of composing a new work every year, Dorati brought one of the world's loveliest sopranos, Heather Harper, to the Kennedy Center in his own Chamber Music. Later seasons were enhanced by his Piano Concerto and Cello Concerto.

For the opening of the orchestra's initial concert in the Bicentennial Year, Dorati had the happy inspiration to program the Third Symphonies of Aaron Copland, Roy Harris and William Schuman. All three works are, and have been for from three to four decades, pillars of the American symphonic repertoire.

For that same year, he also prevailed upon Robert Russell Bennett to put together a stirring score for chorus and orchestra drawn from the writings of early American patriotic composer William Billings.

One of the welcome touches that came at appropriate times in Dorati concerts was the product of his sense for the dramatic. Thus when he was leading the Holidays Symphony by Charles Ives, he made a stunning climax by using entire reaches of the Kennedy Center Concert Hall.

When it came time for the final Thanksgiving choral, every door in the Concert Hall -- from the main floor to the top balcony -- opened and the members of the chorus streamed in to flood the auditorium with the sound. It was precisely the kind of overwhelming effect Ives had dreamed of.

Dorati never hesitated to insist upon extra players when he programmed works that called for more musicians than belonged to the National Symphony. Added brass gave new luster to music from Bruckner to Stravinsky and Walton, thanks to the conductor's determination to present their music as it was intended to be played.

None of the changes and improvements in the orchestra occured overnight. That is not the way things work in the music world. But neither was the progress slow. Before Dorati began conducting the National Symphony in New York City, reviews there had talked about "pallid, dull, routine playing," and had implied that Washington was stuck with its third-rate orchestra. Gradually but steadily, those adjectives began to be replaced by such phrases as "strong playing, marked sense of style," and similar notes of praise.

As with every orchestra Dorati has conducted, the National Symphony began to record again. Out of his first nine recordings with his new musicians, Dorati's work won an incredible six major international prizes.

It is entirely to his credit that the prestige of the orchestra was substantially boosted by such outstanding recordings as their superb "Il Prigioniero," by Dallapiccola, and the "The Mystery of Our Lord and Saviour Jesus Christ," by Messiaen, for which the composer supervised the recordings in which his wife, Yvonne Loriod, is the piano soloist. The recording followed Dorati's presenting the work in its U.S. premiere.

Three years ago, after filling the post of music director for seven years -- exactly the length of time he had told me in Los Angeles before coming to Washington that he thought he would remain here -- Dorati resigned to become music director of the Detroit Symphony, an orchestra he already has presented in a televised series, taken on a European tour and recorded in several best-selling recordings.

With Mstislav Rostropovich installed as music director, Dorati has continued to contribute powerfully to the orchestra each of those years. During those same seasons the orchestra has enjoyed conducting not only by Rostropovich, but such other luminaries as Leonard Bernstein, Claudio Abbado, Lorin Maazel and Erich Leinsdorf, each of whom has commented on the changes that have taken place in the National Symphony.

Rostrophovich has built on the fondations that Dorati strengthened. In listening to the orchestra from week to week and in its new recordings, the solid contribution of Antal Dorati continues to be felt. He will of course return next season to take part in the orchestra's 50th birthday party. After that, it is Washington's good fortune that he will, if less often, continue to return to the orchestra he so mightly helped.