Heavenly it is.
Sift 1 cup of sugar with the cream of tartar. Beat the egg whites until stiff but not dry, gradually adding the sugar mixture as you beat. Spread in a well-buttered 9-inch Pyrex pie plate and bake in a 275 degree F oven for 1 hour. Cool. Beat the egg yolks slightly, stir in the remaining ½ cup of sugar, the lemon juice and rind, and cook in the top of a double boiler until thick. Cool. Whip the cream. Combine the lemon mixture with half of the whipped cream. Spread on the pie and cover with the rest of the whipped cream.