SET FOR "SINKER" BALL: The "sinker" is a valuable pitch in a Major League hurler's repertoire, and Shirley W. Smith used a slight variation last night to embed an autographed baseball in a block of wet concrete. The ceremony was part of festivities at the "author's premiere" of a motion picture based on a story by Smith with a baseball background. Scriptwriter Valentine Davies, who adopted Smith's story for the screen, had previously enslabbed another ball (left) for posterity. The footprint in the cement was made "accidental" (so he said) by Attorney George J. Burke, who acted as master of ceremonies at the premiere.