Sift the baking-powder and salt with the flour, rub in the shortening; then with a fork stir in lightly and quickly sufficient milk to make a soft dough, too soft to roll. Turn it into a greased tin, and bake in a hot oven for thirty minutes. Watch to see that it rises evenly. Unmold, and leaving it inverted, cut a circle around the top, within one inch of the edge; lift off the circle of crust, and with a fork pick out the crumb from the center, leaving about three quarters of an inch of biscuit around the sides. Spread the inside of the cake with butter, and then fill it with crushed strawberries, which have been standing half an hour or more mixed with sugar enough to sweeten them. Turn off the juice from the berries before filling the cake. Replace the circle of crust, and cover the whole cake, top and sides, with meringue, heaping it irregularly on the top. Use a pastry-bag if convenient to give the meringue ornamental form. Place it in the oven a moment to slightly color the meringue. Arrange a few handsome berries on the top. Serve the strawberry-juice as a sauce. Whipped cream may be used instead of meringue, if convenient. Shortcake, to be good, should be freshly made, and served as soon as put together.