Beat the yolks and the sugar together; add the flour, the milk, and the grated rind and juice of the orange. Place it on the fire in a double boiler, and stir until it is a little thickened; then pour it into an open or tart pie, and bake thirty minutes. The crust of the pie should be brushed with white of egg before adding the thickened mixture. The tart crust may be first baked, as directed above, if preferred. Cover the top with meringue made with the whites of the eggs and sweetened with three tablespoonfuls of sugar. Pile it on irregularly, or press it through a pastry-bag into fancy shapes. Place it in the oven a moment to brown. A little more flour may be used if the pie is wanted more solid.