Select a cantaloup of good quality. Cut ripe cantaloup in half, remove seeds, scoop out pulp with a spoon into a saucepan and place over medium heat until it comes to a gentle boil. As it heats you can mash pulp with a potato masher. If you prefer, liquify pulp in a blender before heating.
Mix sugar, flour, and salt together well, then add to heated cantaloup and stir until thickened. Do not cook cantaloup pulp too long before adding flour and sugar.
Beat egg yolks and add 2 tablespoons water. Add beaten yolks to cantaloup mixture and cook until thick and creamy. Remove from fire and add butter. Pour mixture into baked pie shell.
Beat 3 egg whites and 6 tablespoons sugar to make a meringue. Top pie with meringue and bake in 420-450 degree F. oven until delicately browned. May be served warm or cold.