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

This image depicts a curious and fantastical carriage, unlike any horse-drawn vehicle you might be familiar with. Imagine a large metal wagon without the need for horses to pull it. The main body of this carriage is robust and cylindrical, reminiscent of a great barrel. It has a series of sturdy, round wheels, similar to those you might find on a robust cart, yet there are many more than usual.At the front of this carriage is a prominent, large wheel and a complex array of metallic parts which look akin to the workings of a mill, suggesting this contraption might move on its own. This idea is strengthened by a towering fixture atop the front, shaped somewhat like a chimney you might find on a forge or smithy, likely for expelling smoke.There are several rods and handles, suggesting the operation of this device involves intricate mechanisms, possibly leveraging newer forms of artisan engineering far advanced beyond the water wheels and windmills you know. In essence, this drawing shows a self-moving metal wagon, a creation that hints at a marriage of metalwork and unheard-of mechanics, enabling travel without beast or human force. It''s an object of imagination and wonder, challenging the bounds of current craftsmanship and knowledge.