The first reason: during storage of wine in bottle, a series of physical and chemical changes occurred to wine liquid can lead to tartar and pigmentation. When wine bottle is vertically laid, these sediments can sink to the bottom. If the bottle bottom is flat, the sediments are liable to be poured into glass together with the wine, while if the bottle is of mountain shape, the sediments can sink in the concave place without being poured into glass together with wine. The second reason: internally concave cambered surface is firmer; concave pits make bottle bottom be as firm as bottle wall and are designed to prevent bottle bottom explosion. The third reason: in terms of wine service etiquette, concave pits provide convenience and balance for sommeliers during wine service.