The original Pythagoras cup was designed around 500 BC to teach its users to drink in moderation. If liquid is filled into the cup above a specific height, it all completely funnels out of a hole in the bottom of the cup and onto the drinker’s lap. A three-dimensional radiographic exam of a modern Chinese Pythagoras cup was taken to reveal the simple structure of the cup that allows the siphoning mechanism to occur. Though design or object material changes across cultures and time, the functionality of the Pythagoras cup remains the same.
The cup has a neck at its center with an opening at its base. Inside of the neck, which is sealed off at the top, is an inner tube that is open at the top (within the neck) and the bottom (visibly seen on cup surface). As a user pours fluid into the cup, the fluid fills in the neck to the same height as the fluid in the open, visible area of the cup. When a portion of the fluid in the neck overflows and begins to pour down the inner tube by gravity, the remainder of the fluid in the entire cup follows the flow up through the neck and down the inner tube because of reduced pressure and an overall decrease in the gravitational potential energy of the system. The Pythagoras cup is really just a self-priming siphon.
The three-dimensional exam reveals that the inner tube is at a height of approximately 1.20 inches from the bottom layer of the cup. It affirms that the dragon’s head is sealed off from the neck and demonstrates the effectiveness of the Digitome software in accurately measuring object parts and picking up on fine details like the horns of the dragon or the opening in the back of its neck. This video shows a scan upward through the object—Digitome can produce a “stack” of images for an object, and the user can export the stack to commercial software that can then produce a 3-dimensional surface view, as displayed at the end of the video.