AS PART of its December series "The Russians at the Movies: Popular Films of the 1920s," the National Gallery of Art will screen Yakov Protazanov's "Aelita" at 2 Saturday.

A Soviet silent film made in 1924, "Aelita" is about an engineer who escapes to Mars on a flying machine of his own invention. He meets the planet's high priestess and falls in love with her. After he finds himself imprisoned and enslaved, he leads a popular revolt.

Musician Dennis James will accompany the movie on the Theremin, an early electronic instrument invented by Russian physicist Lev Sergevitch Termen. The Theremin is played using the motion of the musician's hands in the space surrounding the instrument.

At 6 Sunday, the Gallery shows "The Kiss of Mary Pickford," another silent Russian movie, inspired by the 1926 visit of Mary Pickford. Written and directed by S. Kozlovskii and D. Kolupaev, it's a comedy about a theater usher whose girlfriend would rather steal lobby photographs of Douglas Fairbanks than hold hands in the dark. The 75-minute film is shown with "One of Many," a 21-minute movie from 1927 directed by N. Khodateyev, in which a star-struck girl dreams she has been transported to Hollywood.

All screenings in the series are free and are held in the East Building of the National Gallery, Fourth Street and Constitution Avenue NW. Call 202/737-4215 for more information.