Green Ravigotte Sauce

Procure green tarragon, chervil, chives, and parsley, in equal quantities; parboil these in water with a little salt until tender; then drain off all the water, squeeze them in a cloth, and pound them in a mortar with two ounces of fresh butter; and having rubbed this through a hair sieve, proceed to incorporate it into some well-made Bechamel sauce, No. 16, or some melted butter: just before using this sauce, add a very little tarragon vinegar and anchovy.