CREATE TABLE table_17487 ("Series #" FLOAT, "Season #" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "Production code" CLOB, "U.S. viewers  ( millions ) " CLOB)

How many viewers, in millions, were for the episode directed by Tawnia McKiernan?
SELECT "U.S. viewers (millions)" FROM table_17487 WHERE "Directed by" = 'Tawnia McKiernan'
SELECT "U.S. viewers (millions)" FROM "table_17487" WHERE "Directed by" = 'Tawnia McKiernan'