Combine the sugar, tapioca, salt, nutmeg, rhubarb, and strawberries, mixing well. Allow them to stand for 20 minutes. Line a 9 inch pie plate with half the pastry and spoon with filling. Dot the fruit with butter. Roll out the remaining pastry and cut it into lattice strips. Fit them over the filling, interweaving the pastry. Bake the pie for 35 to 40 minutes at 400 degrees. This pie freezes well. Freeze before baking if desired.{$7e}(Original recipe for 6)