"There will be a ball in the Winter Palace tonight!" So begins this extended meditation on court life by Sitwell (1897-1988), the poet, critic -- and brother of Edith. Sitwell composed this celebration of the city as Leningrad was under siege in 1941. In this extended essay Sitwell conjures snow and gilt, courtiers, music and pageantry, a military parade, sledges, sables, and Cossacks during the reign of Alexander II.  (RUS209, $22.95)