Handel and Purcell, the two giants of the British baroque period, provided high points in a program presented twice yesterday at the Corcoran Gallery by the Hesperus ensemble. But the graceful Trio Sonata in F of Handel (which sometimes sounds like a recorder concerto) and six songs and a trio sonata by Purcell were flanked and buttressed by a fine variety of interesting works by less-known British composers.

One of the forms explored in the concert was the esoteric but highly enjoyable art of "divisions on a ground," which is rooted in techniques of Renaissance polyphony but points forward to the later development of the solo virtuoso -- and even to jazz improvisation. A very pure example of this exquisite form (composed by Christopher Simpson, who wrote the best manual on the art) was beautifully played by gambists Tina Chancey and Robert Eisenstein, and a set of keyboard variations in similar style by Thomas Tomkins received idiomatic treatment from harpsichordist James Wright.

The high-baroque Concerto in C by John Baston and the Handel trio sonata, inspired some virtuoso recorder playing by Scott Reiss, who was sometimes matched by Chancey on the pardessus de viole--an awkward-looking but agile violin-sized instrument that is held on the lap.

Soprano Ann Monoyios, who has shown such aptitude for medieval and Renaissance music in her work with the Folger Consort, was equally at home in the elaborate coloratura and simple-seeming pathos of Purcell's songs, particularly impressive in the spectacular mini-cantata "Bess o' Bedlam" and the exquisite "Sweeter Than Roses."

Performances were not always note-perfect on the recalcitrant old instruments used by this ensemble, but the style was beautifully precise throughout the evening.