CREATE TABLE table_748 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

What district did incumbent Ralph A. Gamble represent?
SELECT "District" FROM table_748 WHERE "Incumbent" = 'Ralph A. Gamble'
SELECT "District" FROM "table_748" WHERE "Incumbent" = 'Ralph A. Gamble'