A venturi forge uses the Venturi effect to move air through the forge. In order to cause the Venturi effect you need to have a constriction in your design, which is why Pindar's impromptu ceramic shield tapers towards the bottom. Forges have ceramic linings inside them to protect the forge's metal parts from the intense, metal-melting heat within. Amusingly, I came up with the name "venturi forge" - I figured both that the effect would be a useful way of drawing a draft into the forge, and that it sounded like an interesting name for a device - before I looked it up on the Internet and discovered that it's a real thing.

On to more science: If you ever wonder about the scale of the universe, consider that there is an immense, hot ball of gas in galaxy cluster Abell 3266, millions of light years away. The ball itself is three million light years in diameter. That's larger than the Milky Way Galaxy.

Did I mention that the ball of gas is so hot that it's glowing in x-rays? It is.

Even though it's millions of light years away, it appears in x-ray telescopes as a glow in the southern hemisphere, half the size of the Moon.