Question: Who was the incumbent in the district that first elected someone in 1807?
SQL: SELECT "Incumbent" FROM "1-2668378-18" WHERE "First elected" = '1807';

Question: When was someone first elected in the district with incumbent John Smith?
SQL: SELECT "First elected" FROM "1-2668378-18" WHERE "Incumbent" = 'John Smith';

Question: What party represents the district with incumbent Matthew Clay?
SQL: SELECT "Party" FROM "1-2668378-18" WHERE "Incumbent" = 'Matthew Clay';

Question: What party represents the district with John G. Jackson?
SQL: SELECT "Party" FROM "1-2668378-18" WHERE "Incumbent" = 'John G. Jackson';