ONE HUNDRED and 50 years ago today, at 3 o'clock in the afternoon, Franz Schubert died. While he had been in poor health for several months, it was the development of typhoid fever that killed him. He was 31 years and 293 days old.

In that short lifetime, Schubert had written nine symphonies, not one of which was performed while he lived. He also wrote over 600 songs; yet few of them were heard, and those almost exclusively by the small circle of friends with whom he was happy.

Publishers either ignored Schubert or paid him poorly for music the world is now acclaiming as some of the most beautiful ever written.

Many musicians, among them Pablo Casals and Arthur Rubinstein, have called the C Major Quintet "the most beautiful music in the whole world." Yet seven weeks before he died, Schubert had written to H.A. Probst, a publisher in Leipzig, telling him about that quintet in the hope that ii might be published. It was not, until after his death. In that same letter, in understandable despair, Schubert had said, "I am wondering if the trio will ever appear?" This was the E Flat Piano Trio, Op. 100, the score of which Schubert had sent Probst early the previous May. His October letter continued, "I am anxiously awaiting its publication." And the letter ended, "Should any of these compositions by any chance commend themselves to you, please let me know."

"These compositions" were the three final piano sonatas in C Minor, A Major and the B Flat, that radiant work with its ineffable scherzo, and a slow movement to break the stoniest heart.

It is hard for music lovers today to take in these brutal facts about the man who wrote those two perfect movements we call the "Unfinished" Symphony, as well as what the world refers to, quite rightly, as "Schubert's 'Ave Maria.'" It was about this song that Schubert had been able to write to his parents in the summer of 1825:

"People were also much surprised at my piety, which I have expressed in a hymn to the Holy Virgin; this seems to impress everyone and induce devout feelings. I think the reason is that I never force the devout sentiment and never compose hymns or prayers of this kind except when I am involuntarily overwhelmed by it, so that it is usually a real, genuine devoutness . . . "

As to the publication of those songs - for Sir Walter Scott's "Lady of the Lake" - Schubert, indicating how little attention was paid to his own name, added, "I am planning to handle the publication of these songs differently from the usual method, which attracts so little attention; for these will be headed by Scott's honoured name and are therefore likely to awaken greater curiosity, and if the English words are given as well they would make me better known in England . . . "

The musical world is falling over itself this season trying to pay adequate tribute to the music of Schubert, even though, in doing so, most of the anniversary performances are simply repetitions of music that is regularly performed year after year.

Thus Washington heard the song cycle, "Die schoene Muellerin" two nights in a row last week, while several other local performances of it have been set for these fall months. The last of his symphonies, the great C Major work that followed the "Unfinished," was played in the Kennedy Center on Nov. 6, was heard there again on Friday, and will be presented in the National Gallery today.

Andre Watts is now in the midst of a series of eight concerts of Schubert music that he, both in solo recitals and with a chamber ensembles, is taking to cities across the country. That series, like the concerts of the Lincoln Center Chamber Music Society, will include the most heavily fished work in all music, the "Trout" Quintet, recently voted one of the top favorites of the Lincoln Center audiences. It has for several years been heard each New Year's Eve at the Kennedy Center.

Antal Dorati, now in the midst of a Schubert celebration in Detroit, broke the mold of repeating the most frequently played works to give that city the first complete performance of any of Schubert's 15 operas ever heard in this country.

Would Schubert have found all this hectic activity in his behalf ironic? Probably so, and not without some bitterness. He was, after all, the composer of the incomparable setting of Goethe's ballad, "Der Erlkoenig," which the publishing house of Breitkopf & Haertel in Leipzig not only rejected, but which they returned to the wrong Schubert! They sent it back to the insignificant Francis Schubert of Dresden, who wrote to them apologizing for their having been troubled by someone "who thus takes my name in vain and was so uncivil as to send you such wretched stuff . . .!"

Bitter? Yes, undoubtedly. For the last three or four years of his life, Schubert has openly resigned himself to increasingly poor health and a continuing struggle to make ends meet in a life of almost complete obscurity in a city where music was in so flourishing a state.

In the last letter he ever wrote, to his close friend Franz von Schober, Schubert paints a picture that equals - if indeed it does not surpass - even the picture of abject misery conjured up by some of Mozart's most heart-rending letters. On Nov. 12 Schubert wrote to Schober. "I'm ill. For the last 11 days I had nothing to eat or drink. I can only totter feebly from my chair to my bed and back. Rinna [court physician Ernst Rinna von Sarenbach] is treating me. If I do take any food, I cannot keep it down at all.

"In kindness, please come to my aid with some books to ease this desperate situation. I have read Cooper's 'Last of the Mohicans,' 'The Spy,' 'The Pilot' and 'The Pioneers.' If by any chance you have anything else by him, I beg you to leave it for me with Frau von Bogner at the coffee-house. My brother, who is the soul of conscientiousness, will bring it over to me without fail. Or anything else instead. Your friend, Schubert."

Seven days later Schubert was dead. We will never know what symphonies would have followed that epic C Major that stands alongside the symphonies of Beethoven; or what songs would have followed those last songs, among which can be found the immortal "Serenade" and "Atlas." Or the piano sonatas that could have come after that matchless work in B Flat; or trios and quintets to follow those that ended his chamber music.

We do know there would have been more. Schubert's musical imagination was at its highest peak in his final years. There was, rather than flagging, a constant ascent in the creative drive, a continuous unfolding of new and brilliant ideas. It was the body and the spirit that were deprived of the nourishment needed to survive.

Is it any wonder that that last cycle of songs, "Winterreise," the proofs for the last half of which Schubert was working on in the last days of his life, ends with what may be the loneliest cry in the whole musical universe? That final song, called "The Organ Grinder," epitomizes, in its empty accompaniment, and in the bareness of the vocal line, the hollow void which the world had become for Schubert.

Have not the poet's words become Schubert's own?:

Over 'hind the village, stands an organ man,

And with frozen fingers he grinds what he can.

Barefoot, teeth a-chatter, tottering to and fro,

Yet his little platter holds no coin even so.

No one cares to listen, no one spares a glance.

Just the dogs keep snarling round the poor old man.

And he lets it happen, all just as it will;

Grinding on his organ, never standing still.

Strange old man, so wondrous, shall I come with you?

Will you for my own songs grind your organ too?

Dear Schubert, long since in peace since the day that brought you release from the world, see now how it tries to make up for its neglect. Do you, Franz, see another Schubert now among us, unheeded?