LAST SATURDAY EVENING the Bach Society Orchestra warmed up for its spring tour by presenting an admirably chosen series of four works, one from each century since the seventeenth, all of which were well suited to the group's small size and intimate style. The string section opened the concert alone with a Chacony, written by Henry Purcell, which exemplified the highly ornamental and formally structured character of the early English baroque. Christopher Wilkins directed the performance with precise care, drawing from the orchestra a highly refined control over dynamics which contributed to the carefully maintained balance among the various sections. Purcell's formal phrasing never sounded stiff; the orchestra played effortlessly and with great sweetness and purity of tone, and rendered the numerous ornaments in the best baroque fashion. The unpretentious, charming music was an accommodating vehicle for the Bach Society, which managed to project an atmosphere of intimacy and warmth into the airy spaces of Sanders. Theater.

Two weeks after achieving a roaring success playing a Saint-Saens concerto with the Harvard-Radcliffe Orchestra, Roy Kogan was back on the Sanders stage Saturday night. This time he played Mozart's 21st piano concerto, K. 467, a work which lacks much of the flamboyance and virtuosity of the high French romantic style, and which is therefore much more difficult to bring off convincingly. As before, Kogan generated a great deal of excitement with his fluid dexterity and remarkable technique, but he also responded well to the subtler musical challenges of Mozart. Throughout the first two movements he demonstrated his ability to play with emotive expansiveness while maintaining the lightness and delicacy of the music. Occasionally, however, the performance seemed to lose momentarily its sense of direction and its healthy self-confidence. The last movement was taken at an astonishingly rapid tempo which tended to emphasize Kogan's talents as a technician at the expense of his musical abilities. Although his displays of virtuosity were undeniably impressive, they seem better suited to works like those of Saint-Saens than to Mozart's ethereal classicism.

The orchestra never imposed on Kogan's domination of the performance, but under Wilkins's meticulous direction its playing was accurately synchronized with the soloist's. During Wilkins's two-year tenure as its director, the Bach Society has played a considerable amount of Mozart, and now the experience of both conductor and musicians is bearing fruit. The strings exhibited the same cleanliness of ornamentation and sensitivity to dynamic shading as they had shown in the Purcell piece; their playing, like that of the high woodwinds and the timpani, was clean and light. The orchestra and its conductor, as well as the soloist, showed an acute awareness of the unique and difficult problems posed by Mozart, and responded to those challenges with intelligence and grace.

The concert's representative of the nineteenth century was the Siegfried Idyll of Richard Wagner. This composer's propensity for sleeping with the wives of his benefactors is well known, and his scandalous affair with the wife of the distinguished conductor Hans von Bulow finally ended in her divorce and her marriage to Wagner in 1869. In celebration of that event, Wagner composed the Siegfried Idyll, which, in its tranquillity and relative simplicity, contrasts sharply with the stereotype of Wagnerian heaviness and turmoil. Unlike his operas, it is modestly scored, an intimate love poem which Wagner never meant to have published. It is, in addition, an immensely difficult piece to perform--the orchestra is required to evoke a tranquil, exalted atmosphere, and then maintain this mood through twenty minutes of technically exacting music.

Unfortunately, Wilkins and the Bach Society did not entirely succeed in the difficult task they set for themselves. The strings again played sweetly, particularly in the quiet opening and closing sections, and the solo wind passages were impeccably performed. But too often the idyllic atmosphere of the music was disrupted by unnecessary heaviness in the lower instruments, and Wilkins's cautious, fastidious approach to the work detracted from its Wagnerian sweep and passion. Hence, although the performance was as precise as one could wish, it might have been more inspiring. As an ambitious attempt to perform a very difficult work, it was certainly impressive, but it cannot be called entirely successful.

The orchestra concluded the evening by breezing through Prokofieff's Classical Symphony, a spirited work which at once satirizes the formalities of eighteenth century classicism and attempts to reconcile them with the more broadly defined harmonic conventions of the twentieth century. It is scored for the highly classical combination of six pairs of winds, timpani and strings, and its transparent orchestration and rapid, exposed passage work require a great deal of precision and technical skill. The orchestra maintained its accuracy while capturing Prokofieff's mischievous spirit; indeed, the musicians' dexterity seemed to increase as they became more inebriated with the wit and humor of the composer. During the rambunctious Finale, with its amazingly rapid flurries of notes, both the precise control of Wilkins's conducting and the breathless exhilaration of his musicians were very much in evidence, and the orchestra romped down to the final chords with both Prokofieff's neoclassical polish and his youthful exuberance.