With urbanity befitting Thomas Jefferson's Commonwealth, the Virginia Museum Theater has three noteworthy distinctions in the professional regional theater.

It is one of three U.S. professional theaters allied to art museums. The Sarasota, Fla., Asolo Theater flourishes as a product of the Ringling Museum and also as the official state theater. Chicago's Goodman Theater, an adjunct of the Chicago Art Institute, has shaken admirers by announcing its fade-out.

More remarkably, VMT pays 80 per cent of its budget through the box office. Most regional theaters are far more heavily subsidized through public or private sources. VMT must be a substantial success with its audiences.

Most satisfactorily, artistic director Keith Fowler insists on introducing new plays, the mark of a confident, perceptive institution.

Continuing through March 26, its latest new work is "Childe Byron" by Romulus Linney, whose two previous premieres at VMT have been "The Sorrows of Frederick the Great" and "Democracy," adapted from Washington novels of Henry Adams. Both have had critical acclaim, with publication of the first announced for this spring and a new staging of "Democracy" now playing in Philadelphia.

Linney's way with a play is to take a full bite of a character's life, covering years and incidents. In "Childe Byron," with liberal quotations from the colorful poet's works, he has hit on the striking device of having Byron's daughter, Ada, confront her dead father. He was 36 when he died; she is that when she, near death herself, exorcizes his memory. A noted mathematician who grasped the computer principle a century in advance, Ada, countess of Lovelace, confronts her father about his neglect of her and his own scandalous life.

Linney had given Ada the gift of understanding. She does not moralize but her intelligence consumes the facts. In their confrontations, father and daughter come to life. The chunks of incidents and subsidiary personalities are certainly informing, but device pays the dramatic price of being seen and felt sketchily at a distance.

Jeremiah Sullivan's Byron, a bravura part for which the actor is fully capable, thus has two performing levels. He must be seen to be looking back with compassion for his daughter's respect, but he also must be shown as the stimulating, if childlike, egoist who quickened his era. Playing opposite Marjorie Lerstrom's deftly realized, understanding Ada, Sullivan clarifies both levels with presence, voice and command.

Under Fowler's direction, six other performers play the lesser figures with the style inherent in the script and in Sandro La Feris's accommodating setting, simultaneously stern and romantic.

Added to last year's introduction of Gurney's "Children" and workshop performances of New York's currently admired "Ashes," this use of the Ford Foundation's new American plays program is one more mark of Fowler's stimulating eight-year contribution to Richmond's urbane performing arts atmosphere.