What is in this image? Describe it as if you were explaining it to someone from the 15th century.

Imagine a large, fantastical metal carriage that flies through the sky much like how birds soar. Instead of wings, it has a large, swirling disc atop it, which spins rapidly to lift it into the heavens. The body of this sky carriage is somewhat like an elongated, smooth egg, and it has a small door through which travelers can enter. At the rear and the side, there are smaller circles which, unlike regular wheels on a carriage, assist in guiding it when it moves across the ground. This fantastical vessel is used to travel great distances at incredible speeds above the land and sea, transporting people through the clouds.