Cut the salt pork into slices, and fry them brown; chop the onions, and cook them with the pork. Stew separately the tomatoes and potatoes. When all are done, put them together with the clams and their juice. Add three pints of water, salt, pepper, a little thyme, a very little flour for thickening, and the crackers. Stew all together for half an hour, and serve very hot.