While its cousins in the Baltimore Symphony Orchestra plunged into turmoil this week over the appointment of Marin Alsop as their next music director, the National Symphony Orchestra comfortably purred along in summer mode.

The NSO has spent the time performing a light schedule of concerts across the city. As with other orchestras, these months are a time to recharge the artistic batteries, remain musically fit and attract new listeners with zesty musical bonbons.

On Thursday evening, the NSO took full advantage of the awesome dimensions of the National Cathedral and went beyond typical July concert fare. In addition to the usual lighter pieces, the orchestra gave a beautiful rendering of a large-scale sacred choral work and a grand organ concerto. The Cathedral Choral Society and its estimable musical director, J. Reilly Lewis, were key participants in the first part of the concert.

Charles Gounod's "Messe solennelle de Saint Cecile" was the indisputable highlight. Gounod's name cache rests almost exclusively on dramatic operas such as "Faust." Yet the 19th-century French composer created several sacred Masses, and with some moments of crass nationalism in the score aside, this performance took Gounod out of the realm of musical drama.

Under the baton of Lewis, the NSO and the Cathedral Chorus gave a noble account that tied Gounod to larger liturgical choral tradition.

Lewis brought out the full measure of the work through a strong emphasis on color, sweep and contrast. Moving from the gentle repose of the opening "Kyrie," the players and singers added layers of details in the noble chords of the "Credo" and the more songful "Sanctus." The fourth movement, "Offertory," served as calming intermezzo in the midst of strong emotions, and the musicians played it with a rich yet graceful lyricism.

Three skilled soloists made important contributions. Jessica Swink's gem-like soprano soared gorgeously over the orchestra, while Tim Augustin deployed a pleasingly golden tenor. Bass Jon Bruno's singing merged power with agility. Throughout the Gounod, the chorus brought clear diction, warm ensemble and poise to their lines.

NSO Associate Conductor Emil de Cou led the NSO through a warm rendering of Poulenc's Concerto in G minor for Organ, Strings and Timpani, with Lewis the organ soloist. Most composers use the organ to lend a devotional atmosphere to music. Poulenc, instead, explored the wide-ranging sonic qualities of the instrument, fluidly merging a diverse range of styles into a coherent work. Grand outbursts gave way to gentle pianissimos in Lewis's playing, which, unfortunately sometimes covered the sound of the orchestral accompaniment.

In Ravel's "Pavane pour une infante defunte," the NSO played with a somber elegance matched by the coruscating vigor it invested in Britten's "Variations and Fugue on a Theme of Purcell," Op. 34. As the stately theme moved through the orchestra in the latter, each musician deployed thoughtful phrasing, articulation and energy. It may be summer, but the NSO is not on summer vacation.

An abundance of treasures: The NSO's Emil de Cou, above, soprano Jessica Swink and the Cathedral Choral Society's J. Reilly Lewis.