CREATE TABLE "table1_228439_4" (
  "district" text,
  "vacator" text,
  "reason_for_change" text,
  "successor" text,
  "date_successor_seated" text
);

Question: What district is Samuel A. Bridges ( D ) assigned to as a successor?
SQL: SELECT "district" FROM "table1_228439_4" WHERE "successor"='Samuel A. Bridges ( D )';

Question: what was the reason Richard K. Meade ( d ) became a successor?
SQL: SELECT "reason_for_change" FROM "table1_228439_4" WHERE "successor"='Richard K. Meade ( D )';

Question: Who is the successor for massachusetts 8th?
SQL: SELECT "successor" FROM "table1_228439_4" WHERE "district"='Massachusetts 8th';