CREATE TABLE table_18704 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

who is the incumbent for district mississippi 4
SELECT "Incumbent" FROM table_18704 WHERE "District" = 'Mississippi 4'
SELECT "Incumbent" FROM "table_18704" WHERE "District" = 'Mississippi 4'