The “公道杯”Gong Dao Bei, also known as the Fair Cup or Justice Cup, is an ancient Chinese celodon porcelain product used for drinking alcohol. It features a figurine of an old man or a dragon’s head at the center, with a hollow porcelain tube inside the body that connects to a small hole at the bottom of the cup. There is also a hole at the junction between the figurine’s body and the bottom of the cup. When you pour water into the cup, if the water level is below the upper opening of the porcelain tube, it will not leak. However, if the water level exceeds the upper opening of the tube, the water will flow out through the hole in the cup’s bottom. This unique leak-proof cup, known as the “公道杯” in Chinese, is crafted based on the principles of physics, specifically the siphon effect.
The “公道杯”Gong Dao Bei is known for its fairness in serving alcohol. When filling it with alcohol, you must pour it moderately, not too full. Otherwise, all the wine in the cup will leak out, leaving not a drop behind. This ingenious cup ensures that drinks are served justly and encourages moderation in drinking.
The "公道杯" is a utensil created using the principle of a "siphon" or "communicating vessel" from physics. This principle allows for the controlled flow of liquids between interconnected containers.
