Mayonnaise Sauce a la Bayonnaise

Lay five egg-yolks in a bowl with a quarter of a gill of water, half an ounce of salt, a little pepper and a little cayenne, then beat it up and incorporate slowly into it two and one-half pints of oil and one gill of vinegar, stirring it unceasingly, and when the sauce thickens add to it more vinegar, and continue pouring in the oil and vinegar till they are both consumed. It must be of a high consistency, of a white color, and of a good flavor; it is preferable to use a wire whisk in place of a wooden spoon for this purpose. Add to this mayonnaise half a pound of lean Bayonne ham, cut in squares, some powdered Spanish peppers, and some chopped parsley.