From "The Whitehouse Cookbook" - 1887:

Beat the yolks of twelve eggs very light, stir in as much white sugar as they will dissolve, pour in gradually one glass of brandy to cook the egg, one glass of old whisky, one grated nutmeg, and three pints of rich milk. Beat the whites to a froth and stir in last.

From "The Elegant Art of Dining, Bohemian San Francisco Its Restaurants and Their Most Famous Recipes" - 1914

VIRGINIA EGG NOG:    Beat separately the yolks and whites of ten eggs, the yolks to a soft cream. To the beaten yolks add one pound of granulated sugar, beating until fully blended and very light. Let one quart of fresh milk come to a boil and pour over the yolk of egg and sugar, stirring constantly until well blended. To this add one gill of French brandy or one-half pint of good whisky. On top of this place the beaten white of egg and grated nutmeg. Serve either hot or cold.

From "Aunt Caroline's Dixieland Recipes" - 1920  

EGG NOG—MARYLAND STYLE: Beat the yolk of one egg, add a teaspoonful of sugar, and a small pinch of salt, then pour in slowly stirring all the while a cup of milk. Pour in a glass and put spoonful of whipped cream on top and any quantity of "flavoring desired."