HANDEL: Theatre and OUtdoor Musick. Kenneth Cooper, harpsichord (Vanguard VSD 71224). The tune could hardly be more familiar; it is the great, arching Hornpipe from the Water Music, the marvelous tune for horns in which that instrument's gold-and-brass gleam achieves a luster unimagined by any composer before Handel. But there is something radically different on this record; the horns are gone and a solo harpsichord is playing the music. This is the most disorienting moment, and in many ways the most fascinating, in a record that abounds in interest and in disorientation.

Besides a suite from the Water Music, Cooper plays a variety of orchestral works (overtures and dance movements) from Handel's operas and oratorios and a harpsichord sonata based on the material that was also used for a flute sonata, Opus 1 No. 11 and an organ concerto, Opus 4, No. 5. Apparently this last item (which sounds quite idiomatic and is, like all the material on the record, superbly played) was Cooper's idea, but the rest of the material on the record is from transcriptions issued by Handel's publisher during the composer's lifetime.

This is a delightful record, most often presenting music that is seldom if ever heard and sometimes presenting familiar music in a striking new perspective. The use of the harpsichord for orchestral music demonstrates effectively the richness of color available on that instrument. Highly recommended for anyone whose tastes run even slightly off the beaten path.

BACH: French Suite No. 5, English Suite No. 3, Toccata and Fugue in D, Capriccio in B flat (On the Departure of His Beloved Brother). Wilhelm Kempff piano (DG 2530 723). Can we praise a collection of orchestral music played on the harpsichord and then condemn a collection of harpsichord music played on the paino? We can, I suppose, but Kempff makes this kind of snobbism a bit more difficult with performances of such finely disciplined clarity and sense of form; his view of this music is one well worth having, and one must take it on the piano since that is what he plays. To do justice to Bach's style, he sacrifices the impressive dynamic resources of the modern piano, and he does without the variety of voices that the harpsichord offers in compensation. But he presents this music nonetheless superbly. Those who insist on the sound of plucked (rather than gently hammered) strings may ignore this record. Others will find it a delight.

Music for Virginal: Works of Byrd, Farnaby, Bull, Gibbons and Tomkins. Colin Tilney, Virginals (Archive 2533379). Most of these 13 pieces from one of the brief but spectacular golden ages of British music (the period extending a few decades on either side of the year 1600) are actually played on the harpsichord. It should matter little to the nonspecialized listener playing the record for pleasure; the chief difference is that the harpsichord has resources unavailable to the smaller instrument, and Tilney properly restricts his harpsichord to the kind of sounds also available on the good virginal. He has chosen well among the available music of the period (chiefly elaborated dance forms, a few sets of variations and a couple of preludes), and he plays the music with a fine sense of appropriate style. A sort of bonus, in the three pieces played on the virginal (a fine instrument built in Antwerp in 1580), is the audibility of the instrument's action - a nice touch of authenticity.

Jos Van Immerseel Plays Historic Flemish Harpsichords: Works of Mozart, Balbastre, Sweelinck, Bull, Bach and others (Odyssey Y 34632). For the two centuries during which the harpsichord flourished, Antwerp was a key center for the manufacture of the instrument and it is now the site of a museum housing some notable specimens. Three of these, as much as the music, form this record's chief point of interest; each of the three is displayed in music of appropriate vintage (including one that is actually a virginal), and the music is well played and recorded.

Music of Jacques Duphly. James Weaver, harpsichord (Smithsonian N 004). Duphly is not totally unknown, but I believe this is the first record devoted entirely to the work of this final representative of the great school of Couperin and Rameau. The quality of the music indicates that such a recording was overdue - an impression reinforced, no doubt, by the precision and fine style of this preformance. Here, too, the instrument (the Smithsonian's excellent, Stehlin harpsichord) is of special interest, and it is discussed, as well as the music, in Weaver's illuminating liner notes.