Science in the Kitchen by E. E. Kellogg

12. Do not hang the napkin about the neck like a bib, but unfold and lay

across the lap in such a manner that it will not slide to the floor. Carefully wipe the mouth before speaking, and as often at other times as may keep the lips perfectly clean of food and drink. At the close of a meal, if at home, fold the napkin neatly and place it in the ring. If at a hotel or away from home, leave the napkin unfolded by your plate.