Put water in a pan. Sprinkle gelatin on top; let stand at least 5 minutes. Beat egg yolks and sugar together until pale and fluffy.

Add lime and lemon rind; mix to blend. Cook gelatin mixture over low heat until dissolved. Add egg yolk mixture; cook gently, stirring constantly, 3 to 5 minutes. Don't let mixture boil or it may curdle. Remove from heat; stir in rum, lemon and lime juices. Cool until just beginning to gel. This can be hastened by setting bowl on bed of ice. Stir occasionally to prevent jelly forming. Whisk cream in bowl until soft peaks form. Fold whipped cream and beaten egg whites into gelatin mixture. Pour into prepared dish. Chill. Decorate with whipped cream, violets, and lime slices.