When did the no. 23 show originally air?
CREATE TABLE "table1_10718984_2" (
  "no_in_series" real,
  "no_in_season" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_millions" text
);
SELECT "original_air_date" FROM "table1_10718984_2" WHERE "no_in_season"=23;