Whip the egg whites until frothy and then add the cream of tartar, continue beating until the egg whites are very stiff and form peaks.
Gradually beat in the sugar and continue beating until the whites are stiff and glossy Spread into a 9" pie plate and bake in a 250F oven for 1 hour.
Filling: Beat the egg yokes until thick.
Gradually beat in the sugar, add lemon juice& rind with the bit of salt.
Cook in a double boiler until thick, stirring constantly.
Whip the cream (have the cream very cold and cool your bowl in the fridge too,) Add a little sugar to the cream, beat until stiff When the crust is completely cooled spread half the whipped cream in the shell, then half the lemon filling, top with remaining whipped cream Put in the fridge for 3-4 hours or overnight.