CREATE TABLE table_72436 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

what year was william francis stevenson first elected?
SELECT "First elected" FROM table_72436 WHERE "Incumbent" = 'William Francis Stevenson'
SELECT "First elected" FROM "table_72436" WHERE "Incumbent" = 'William Francis Stevenson'