As we approach Leonard Bernstein’s 100th birthday on August 25, I’ve been featuring a number of his lesser-known pieces in this space. Here’s another: The “Elegy for Mippy II” for solo trombone, composed in the late 1940s. Mippy was the name of Bernstein’s brother’s dog. The score instructs the player to provide a foot-tapping accompaniment. Ximo Vicedo is the trombonist in the video.