For the second week in a row the National Symphony Orchestra is playing marvelously for an eminent American guest conductor -- in this case, Leonard Slatkin of the St. Louis Symphony. During much of Thursday night's concert, Slatkin coaxed from the players a radiant warmth and sensitivity, strikingly different from the more heroic timbres they produced for Michael Tilson Thomas just before Slatkin.

These exquisite sounds were especially suitable to Dvorak's Symphony No. 8 in G (Op. 88) -- that gloriously poised and seemingly spontaneous outburst of bucolic melody and quicksilver musical colors.

The phrasing was worked out in the most complete detail, with the most beautiful dynamic and rhythmic inflections. The Eighth must breathe, and Thursday night it did.

There is a special sound to the symphony that is duplicated in no other work; to overplay it is to damage it. The Eighth Symphony must be caressed, not driven.

And that is exactly how it went Thursday night. Slatkin went to enormous lengths to keep strings and winds in proper balance. There was much soft playing -- really soft. And the result was a tonal depth that seemed to rise easily out of the orchestra. It is a great credit to both Slatkin and to the National Symphony that this elusive combination of musical elements could be attained with just a few rehearsals.

The Dvorak was hardly the only beautiful thing of the evening.

Itzhak Perlman was soloist in the rarely heard A minor Violin Concerto of Karl Goldmark. It is more a work for violin than a work for orchestra. For all its virtouso display (the third-movement cadenza was extraordinary, the way Perlman played it), the concerto is basically a gentle work, full of color and pleasing, but not profound, melody.

The other performance was not exactly melodic. It was the Washington premiere of "Sequoia," a three-movement tone poem written in 1981 by Joan Tower, who is based in New York.

"Sequoia" is scored for an enormous orchestra and is one of those kinds of works in which large bodies of instruments at different registers and in shifting textures are combined in a multitude of often mysterious and evocative combinations, propelled by a persistent ostinato beat. The title was suggested, writes the composer, by the inherent "power and majesty" of the tree.

On first hearing, the mighty sonorities are appealing (talk about fortissimo, you get plenty of it here), but one is left unsure about how well the composition would wear on repeated hearings.

It was powerfully played.