Cut melon in half and scoop out seeds.
Cut a thin slice from the bottom of each half so they stand straight. Place each half on a plate.
Pour gelatin into a bowl. Pour in 1 cup of boiling water. Stir with a rubber spatula until powder is dissolved. Stir in 1 cup of cold water.
Carefully pour gelatin into melon halves. Chill in the refrigerator for 4 hours, or until firm. Remaining gelatin can be poured into custard cups for individual servings.
Slice melon into wedges and serve.