To make the pastry dough, put the flour and salt in a mixing bowl; using a fork to stir, distribute the salt throughout the flour.
Add the shortening and break into small chunks. Either lightly rub the chunks into small pieces throughout the flour or use a pastry blender to cut the shortening into the flour. Mix lightly until the mixture resembles coarse meal. The texture won’t be uniform but will be made up of small pieces and crumbs.
Sprinkle the water over the flour mixture 1 tablespoon at a time, mixing lightly with the fork; add only enough water so the dough will hold together when pressed gently into a ball. If there are dry places that don’t adhere, sprinkle a little more water over them. Put the dough in a bowl, cover, and chill in the refrigerator while you prepare the apples.
To make the apple filling, put the sugar, cinnamon, allspice, nutmeg, and flour in a large mixing bowl. Add the apples and the lemon juice, and toss together gently but thoroughly.
Preheat the oven to 425 F. degrees.
Divide the dough in half. Roll out one half about 2 inches larger than the pie pan. Transfer the dough to the pan, fitting it in loosely but firmly all around.
Fill the pie shell with the apple mixture, mounding it somewhat higher in the center. Although the apple filling may appear quite high, it will shrink considerably during the baking. Dot the top of the filling with the butter.
Roll out the remaining half of the dough into a circle the same size and thickness as the bottom crust. Roll it up on the rolling pin, and then unroll, starting at the edge of the pie and letting it drop so it is draped over the filling.
With scissors, trim the top crust, leaving about ¼ inch of crust over the edge of the pie pan. Tuck the overhanging ¼ inch under the edge of the bottom crust all around the rim and then press down with the tines of a fork to seal the two crusts together.
Cut two small gashes in the center of the top crust to allow the steam to escape.
Place the pie on the middle rack of the preheated oven and bake for 30 minutes. Reduce the heat to 350 degrees and continue baking for 20 to 30 minutes more.
The pie is done when the apples are soft. Test by piercing through the gashes into the apples to make sure they are tender. If the pie starts to become too dark, cover loosely with aluminum foil.