When james brooks (d) is the vacator what is the date the successor was seated?
CREATE TABLE "table1_2147588_4" (
  "district" text,
  "vacator" text,
  "reason_for_change" text,
  "successor" text,
  "date_successor_seated" text
);
SELECT "date_successor_seated" FROM "table1_2147588_4" WHERE "vacator"='James Brooks (D)';