Stephen Simon and the singers and instrumentalists gathered in the Kennedy Center yesterday afternoon, presented Handel's "Julius Caesar" with its many beauties handsomely set out, and, from time to time, some real excitement and fire.

The orchestral writing is glorious, with strings in highly sophisticated passages, and exquisite solos for flute, horn, and violin, while to these are added notable ensemble moments from other winds. The vocal writing is a succession of richly imagined and stunningly apposite musical portraits of very real personalities.

Giving the title role of the virile Caesar to the modern bass-baritone instead of the castrato for whom Handel wrote it is an admitted necessity. But Egypt's Ptolemy was quite as much a king as Caesar, and it was strange to hear the African monarch sung by a young countertenor. Yet, Sextus, Pompey's young son, sounded just right sung by the Canadian mezzo, Huguette Tourangeau, who, in her Washington debut, made a brilliant success. Perhaps the answer lies in the vocal sounds supplied by each singer, and the skill with which they project Handel's lines.

Tourangeau uses three or four kinds of vocal production, but the passion and intensity of her art swept away any worries about technical matters. Her final vengeance scene started truly Handelian fires.

These had burned as brightly earlier for Beverly Wolff, singing Cornelia, the widow of the murdered Pompey. Wolff, who has sung both Cornelia and Sextus, makes the music and drama her own in a singular manner, for which she was loudly rewarded.

Elaine Malbin, absent from concert halls for some years, took on the demands of Cleopatra with some success, growing more secure and expressive as she moved into the drama. But the great "Se pieta" was far from what it should have been, lacking precisely the kind of involvement Wolff and Tourangeau were supplying so richly. However, from the sounds she offered, it seems likely that Malbin can look toward a second career.

Dominic Cossa, long an expert Achillas, sang with style and excellent vocalism, as did the young baritone Jan Opalach as Curio. Kimball Wheeler, though not fooling anyone about being an "old minister to the crown," sang handsomely. Gene Hill was the Ptolemy, his musicianship going far to make up for a voice of little quality or appeal.

Morley Meredith took on the title role. His voice has a somewhat hollow sound that keeps agile lines from coming across convincingly. In quiet passages he was affecting, without probing them deeply.

Simon's guiding hand kept all the right elements in Handel in fine proportion.