Line a 9-inch pie plate with bottom pastry. Trim to 1 inch beyond edge of plate.
In a large bowl, combine the pears, apples, 1 cup sugar, lemon juice, cinnamon, and nutmeg. Pour mixture into crust. Dot with butter.
Roll out remaining pastry to fit top of pie. Cut slits in pastry. Place over filling. Trim, seal and flute edges. Brush with milk; sprinkle with remaining sugar. Cover edge loosely with foil.
Bake at 350°F for 30 minutes. Remove foil. Bake 30 to 35 minutes longer, or until crust is golden brown. Cool on a wire rack.