Clams (presumably shelled)
Pepper, either black or cayenne
Wine, catsup, or other sauce
Fry five or six slices of fat salt pork crisp, and chop to pieces. Sprinkle some of these in the bottom of a pot; lay upon them a stratum of clams; sprinkle with cayenne or black pepper and salt, and scatter bits of butter profusely over all; next, have a layer of chopped onions, then one of small crackers, split and moistened with warm milk. On these pour a little of the fat left in the pan after the pork is fried, and then comes a new round of pork, clams, onion, etc. Proceed in this order until the pot is nearly full, when cover with water, and stew slowly–the pot closely covered–for three quarters of an hour. Drain off all the liquor that will flow freely, and, when you have turned the chowder into the tureen, return the gravy to the pot. Thicken with flour, or, better still, pounded crackers; add a glass of wine, some catsup, and spiced sauce; boil up, and pour over the contents of the tureen. Send around walnut or butternut pickles with it.
From Common Sense in the Household by Marion Harland, New York, 1871
Comment: We do not wish to start sectional conflict between the partisans of New England-vs-Long Island clam chowders here, so we will merely point out that, not only is “catsup” not the only flavoring agent permitted here but that “catsup” was not the same product in that day that it is now. Catsups were commonly made with a base ingredient such as fruit, walnuts, and mushrooms as well as tomatoes. Use what you prefer, and give us time to duck behind a tree before you commence discussing the matter amongst yourselves.
The issue of crackers must be addressed as well, since there are few products sold under that name today which can be split into top and bottom halves. Common saltine crackers, oyster crackers or similar items can be used whole. The major difference between this and the commercial chowders available in cans today is the absence of potatoes, but the crackers serve the same essential function of a starch here.