Pour 3 cups boiling water gradually over cornmeal in a large bowl, stirring until smooth. Add salt and butter, stirring until well blended; let stand 10 minutes. Gradually stir in milk and eggs. Stir in baking powder. Pour mixture into a lightly greased 13- x 9-inch baking dish.
Bake at 375° for 45 to 50 minutes or until lightly browned.