Those who have not yet made the acquaintance of the large library of historic recordings on Newport Classic should be remedying that oversight. They are remarkable, both for content and presentation.

One suspects that John Ostendorf has much to do with ferreting out and committing to disc some intriguing, little-known music that has been passed over in the rush to the popular and obvious. At any rate, Ostendorf's program notes place each composition in its historic context, and give interesting and informative sidelights about performance and composers.

Handel's "Siroe" (1728) was steamrolled by the rollicking "Beggar's Opera," which came out in the same season and pointed a more naturalistic path for opera in England. English music lovers, fed up with Italian style, singers and affectations, abandoned Handel en masse, after 10 years of lionizing his stage works. Handel continued his fight for Italian opera for another 10 years, but after "Siroe," the rest was essentially downhill.

Nonetheless, "Siroe" had its enthusiastic supporters, as it well may today. It's basically the story of King Lear - in this case Cosroe, king of Persia - a ruler who wants to assign his kingdom before his death, and picks the wrong son, preferring flattery to honesty. Various convolutions of disguise, treachery, intrigue and deception threaten disaster, but good eventually triumphs.

"Siroe" was a vehicle for Handel's famed Italian sopranos, Faustina Bordoni and Francesca Cuzzoni (notorious for their feuds offstage) and the castrato Senesino. And Cosroe did indeed have a family of remarkable vocalists - one son, Siroe, a mezzo-soprano, and the other, Medarse, a castrato, now of course sung by countertenor.

D'Anna Fortunato is at her most opulent and accurate in the title role, with Julianne Baird full of spectacular fireworks as Siroe's lover, Emira. Basso Ostendorf sings Cosroe with feeling, spirit and rare technical command, though Steven Rickards is a little understated as Medarse. There is no chorus, all soloists combining in a final hymn of love.

One must marvel at Handel's endless melodic fecundity, displayed in 22 arias da capo, and his affecting way with a recitative. Perhaps I would have voted with the "Beggar's Opera" contingent after a dozen or so of these overloaded, stylized and probably over-produced extravaganzas, written according to formula. Yet Handel opera is what it is, and this is a remarkably well-sung and melodically attractive work, directed in authentic sound and appealing style by Rudolph Palmer.

Telemann is not the first name that comes to mind when thinking of baroque opera; but judging from "Pimpinone," Telemann was an inventive technician and master melodist for the lyric stage as well.

Most think of him as the contemporary and teacher of Bach, famous for his polyphony and church music. This omits the fact that he was director of the opera in Hamburg from 1721 until his death in 1767, writing 40 operas and supervising production of other composers' works. Of the 40, only "Pimpinone" survives in full score - an intermezzo, to be sung between the acts of a longer, probably tragic opera.

The ugly bachelor, Pimpinone, despairs of finding a wife; but along comes Vespetta, a conniving servant girl who wraps him around her finger, marries him, and seems set to give him a lifetime of misery. The plot is similar to Pergolesi's "La Serva Padrona," though Vespetta is a thoroughly vile little person, without redeeming humanity. However, Hamburgers seem to have liked their humor broad and heartless.

Nothing could be better than the singing. Baird's voice is beautiful, her technique flawless, and she seems to thoroughly enjoy portraying a character who progresses from saccharine servant to screeching harridan.

Ostendorf is at his best, tone painting the bumbling, simple Pimpinone with utter sincerity. For total fun, hear his aria for three characters - the abused husband in natural voice, the gossipy wife in falsetto, and the weepy wife in assumed voice - each spitting out phrases on the heels of the last. Again Palmer collaborates with warmth and vitality.