Question: How many seats became avaliable in Massachusetts 3rd district?
SQL: SELECT COUNT("Vacator") FROM "1-224840-4" WHERE "District" = 'Massachusetts 3rd';

Question: Who left office on November 26, 1800?
SQL: SELECT "Vacator" FROM "1-224840-4" WHERE "Date successor seated" = 'November 26, 1800';

Question: Who was the latest to take office in Massachusetts 3rd district?
SQL: SELECT "Successor" FROM "1-224840-4" WHERE "District" = 'Massachusetts 3rd';