Arthur Fielder, who in his 50 years as conductor of the Boston Pops Orchestra was probably heard and seen by more people than any other conductor in history, died peacefully in bed about 7:30 a.m. yesterday in his Brookline, Mass., home.

The world-renowned leader conducted the first orchestral recording ever to sell over 1 million copies; his total record sales reached well over 50 million, and in his honor grateful cities named days and weeks.

At the age 84, the noted musician for whom Boston named a bridge, who delighted in being an honorary fire chief, honorary ferry boat captain, honorary cable car conductor, honorary Otoe Indian chief, who loved to ride to fires on a hook and ladder and to scenes of crimes in Boston police cars, gave in at last to a combination of age and the heart trouble that had bothered him since 1939.

President Carter said music lovers everywhere would be saddened by the death of Fiedler who "had a special place in our hearts as the courtly man who introduced millions to the infinite variety and pleasures of music," according to Reuter. President Carter added in a statement: He knew how to take music seriously without taking the fun out of it, and he shared that gift with all of us."

Lenoard Bernstein, who like Fiedler gained fame for bridging the classical and popular worlds in his young people's concerts and his musical scores like "West Side Story," said, "Arthur Fiedler was probably the most popular single conductor in the world. He will be sorely missed by millions as well as by myself for his generous and ebullient nature, his integrity, and his inspiring energy. He was unique and irreplaceable."

[Eugene Ormandy, music director of the Philadelphia Orchestra, called his friend and colleague "a musical institution. He enjoyed life to the fullest and in doing so brought the joy of music to millions people . . ." Seiji Ozawa, musical director of the Boston Symphony Orchestra, telephoned from Japan to relay his "condolences and affection" to Fiedler's wife, a family spokesman said.]

Nothing about his life was routine. Born in Boston on December 17, 1894, Fiedler was accepted at the Boston Latin School at the age of 12. By the time he was 20, he had gone to Europe with his parents, Emanuel and Johanna Fiedler, studied violin, chamber music, and conducting there, and at the outbreak of World War I, returned to Boston where Karl Muck, the great conductor of the Boston Symphony Orchestra, invited him to play the violin, the same kind of invitation that had brought his father over from Vienna in 1885, when the orchestra was new.

After a single season among the violins, Fiedler switched to the viola. He said later in his life that before he ended his 23-year career in the orchestra, he had played six or seven instruments, including the celeste, piano and organ.

It was not until 1929, however, that the association that was to make his name famous throughout the world came into view. Convinced that there should be free outdoor concerts for music lovers in Boston, especially for children, Fiedler coaxed, persuaded, and helped to raise funds for a series of free progams to be played on the Esplanade along the Charles River. These became such instant successes that on February 3, 1930, it was announced that "Arthur Fiedler, widely known Boston Symphony musician, will be the conductor of the pops concerts at Symphony Hall next spring." He was the first Bostonian to lead the pops.

From then on, the unbroken procession continued: concerts in the hall at the end of the symphony season, followed by the free outdoor concerts, on the Esplanade. Last year crowds of around 250,000 hailed Fiedler as he moved toward his 50th annual appearance there.

Fiedler met with some reporters one week ago today, on the first Fourth of July in 51 years that would not see him at the head of his beloved Boston Pops. "I regret that I'm not with them all," he said. "I feel a little melancholic." With the blinds drawn in his room, he listened to the concert over the radio, hearing his wife, Ellen, read the narration in "A lincoln Portrait" by Aaron Copland.

Only once was that series broken. In 1955, he underwent surgery that would not wait, no matter how strongly Fiedler protested that he had to conduct the opening concert. For many of those years, he also opened the Red Sox season leading "The Star Spangled Banner."

By 1935, Fiedler and the Boston Pops had become such drawing cards that he signed a contract with RCA Victor for a series of recordings that began on July 1 of that year and continued until April 13, 1974, when they made their last records for Victor.

From that first session in 1935 came a typical Fiedler triumph: "Jealousy," by the then unknown Danish composer, Jacob Gade. Fiedler had found the music in a second-hand store in Boston, bought it for 15 cents, arranged it, and argued the victor people into letting him record it. It became the first orchestral record to earn a gold record for selling over 1 million copies.

In the years that followed other Fiedler singles totaled over 20 million in sales, and the label, "Fiedler and the Boston Pops" made the contuctor's mustached face known throughout the world of music. A trappist monk who answered a knock at the door of a Canadian monastery one day, took a look at two men standing outside, and broke his customary silence to ask in surprise, "Isn't that man there Arthur Fiedler?"

In Caracas, Venezuela, a bulfight band, recognizing Fiedler in a hugh, rain-soaked crowd, demanded that he conduct them, and improved their playing in appreciation. On a vacation -- he thought -- in Yucatan, Mexico, Fiedler was litrally forced by the mayor of Merida and his fellow townsmen to conduct the local band in an outdoor concert with no rehearsal, and instruments Fiedler never had seen in an orchestra before. He conducted, winning the nickname "Don Musica."

In spite of his assiciation with the Boston Symphony under conductors Muck, Rabaud, Monteux, Koussevitzky, Munch, Leinsdorf, and Ozawa, it was only in the season of 1955-56, under Munch, that Fiedler conducted the orchestra in a regular Symphony Hall subscription concert. The honor was not even repeated for him when he reached his 50th anniversary with the orchestra in 1965. Koussevitzky had asked Fiedler to take a pair of concerts in 1944, and then, in a characteristic rage at hearing that the popular leader had agreed to conduct for a Frank Sinatra concert in Symphony Hall, "dis-invited" him. The Sinatra concert was canceled by the young singer, but "Koussy" never withdrew his dis-invitation.

Since Boston Pops recordings were outselling the great records made by Koussevitzky and the symphony, it would be easy to imagine that some substantial jealousy could have been troubling the older man.

Fiedler's conducting always was marked by complete authority in whatever music was in front of him. On the occasion that he conducted the Boston Symphony under the Munch regime, which was radically different from Koussevitzky's, the Boston Post reported," "Fiedler asked for that wonderful old Koussevitzky tone and got it." The words "clear . . . balanced . . . energetic style" and others were used then, as they often have been in describing the Fiedler approach.

The kind of greatness attached to the fabled conductors of his lifetime -- Toscanini, Stokowski, Koussevitzky -- was never Fiedler's attainment. In part, the reason for this was that he made a deliberate choice in purpose, one that involved repertoire, style, technique and attitude. But that may have precluded in ultimate in interpretive depths. In any case, it was an approach that brought the conductor and millions of devoted fans their chief joy.

Fiedler conducted not only the Pops, but also in concert halls, over the radio, and on records, the Fiedler Sinfonietta, with organists E. Power Biggs and Carl Weinrich, and composer-violist Paul Hindemith, in music by Mozart, Handel, Telemann, and Hindemith. With the Pops he conducted for the great and famous: Duke Ellington, Kate Smith, Peter Nero, Al Hirt, Earl Wild. He was the conductor for one of Margaret Truman's two Victor recordings.

With his encyclopedic knowledge of old and new music, Fiedler was far ahead of his time in March 1940, when he recorded the Pachelbel "Cannon" that has become one of today's biggest hits.

It came as a shock to Fiedler several years ago when RCA announced that it was relinquishing its rights to record the Boston Symphony and the Pops. For a time Fiedler felt that he could not transfer his affections from his longtime association with the Victor label. It had begun in September 1917, when he went as a member of the Boston Symphony to Camden, N.J., to take part in the orchestra's first recording.

However, when Victor gave up the Boston Symphony, Deutsche Grammophon, greatly interest in signing the orchestra, insisted that it get the Pops, too. Since 1974, Fiedler has continued his recording career on the West German label, including among his latest releases a symphonic arrangement of music from "mass," by Leonard Berstein, whom he has known for most of the younger musician's life.

Fiedler never allowed his life to settle into any familiar routine. A lover of beautiful young women, he kept up the appearance of a completely satisfied bachelor until he was 46. Then, after what could hardly be called either a courtship or an engagement, he married Ellen Bottomley, a Boston Brahmin 20 years his junior, and, within the next 10 years, became a father of two daughters and a son.

Married in the reactory of Boston's Holy Cross Cathedral, Fiedler, who was not a Catholic, refused to kneel for the final blessing, but simply turned when his new wife rose, and said to her, "How do you do, Mrs. Fiedler."

Their first daughter was named Johanna, after Fiedler's mother.A year-and-a-half later, when his mother-in-law asked where he had gotten the name "Deborah" for the second baby, Fiedler replied, "Out of the phone book," which he said was completely true.

In his younger days, Fiedler loved to play jokes on his colleagues in the BSO, putting lewd pictures in the scores on their music racks, or making rude noises during rehersals. At the very same time he was acting as singing coach and playing the piano for Mrs. Alvin T. Fuller, wife of the governor of Massachusetts at the time of the Sacco-Vanzetti upheaval.

Mrs. Fuller, before her marriage, had studied singing and had gone to Paris hoping for a career in opera. She became one of Fiedler's closest friends, and with her husband, frequently contributed to the costs of the concert shell on the Esplanade, an organ for the shell, and other things needed to make Fiedler's dream of outdoor concerts on the banks of the Charles River both a comfortable and effective one.

In 1918, when Fiedler was drafted into the U.S. Army, even though seriously underweight, he lasted just two weeks in uniform before he was thrown out for flat feet.In World War II, he would not let any such feeble excuse keep him from serving. He enlisted as an apprentice seaman in the Coast Guard and served on patrol boat 36033, patrolling Boston Harbor in the days when the Queen Mary and the Queen Elizabeth were secretly towed in for repairs.

Fiedler's years with the Boston Pops made his name as familiar in the Soviet Union as in Japan. When Munch took the Boston Symphony to Moscow for the first time in 1956, Russian officials greeted him by asking, "But where is Fiedler?"

In Japan he rehearsed a Japanese orchestra that he proceeded to bring to this country for a nine-week tour. In Tel Aviv he led the Israel Philharmonic in its first pops concert. When Fiedler went to Ireland, they called him "the visiting fireman from Boston." In Kentucky, he became a Kentucky colonel. In Vicksburg, Miss., he was made a colonel in the Confederate Air Force.

By 1953, Fiedler was more in demand than ever, while at the same time the lengthening seasons of the Boston Symphony made it impossible for him to use that orchestra's players for his long tours. So he formed a new Boston Pops Tour Orchestra, auditioning players from all over the country.

Whipping these musicians into shape, he took them on an 83-day tour that saw him conduct 81 concerts in 79 cities in 22 states and Canada.

More than once in times of physical crises in Fiedler's life, Ellen Fiedler said to her husband's doctors, "If you do not let him conduct he will die." Not long ago Fiedler was asked when he would retire. "When I do," he answered, "it will be because I feel physically I cannot go on or when they bounce me out."

He is survived by his wife, Ellen, their daughters, Johanna and Deborah, and their son Peter. CAPTION: Picture, Arthur Fiedler leads the Boston Pops at a concert March 25, his first appearance after neurosurgery several months earlier. AP